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457682 | Conformational changes associated with complex formation between a mycobacterial polymethylpolysaccharide and palmitic acid. | The anomeric proton magnetic resonances of Mycobacterium smegmatis 3-O-methylmannose polysaccharide have chemical shifts intermediate betwen those of nonaglucoamylose and alpha-cyclodextrin, and on addition of palmitic acid most of these resonances are shifted upfield toward that of the cyclodextrin. This suggests that... |
228052 | Induction of thymidine kinase and DNase in varicella-zoster virus-infected cells and kinetic properties of the virus-induced thymidine kinase. | Thymidine kinase (TK), DNA polymerase, and DNase activities were induced in human foreskin fibroblasts after varicella-zoster virus infection. The induced TK and DNase activities have electrophoretic mobilities different from the corresponding host enzymes. Varicella-zoster virus-induced TK was purified and separated f... |
158759 | Regulation of ribosomal protein synthesis in Escherichia coli by selective mRNA inactivation. | In an Escherichia coli strain lysogenic for lambda spc2 transducing phage, an extra copy of ribosomal protein (r-protein) genes in the spc and alpha operons are carried on the phage chromosome. Expression of genes in the spc operon in this merodiploid strain was compared with that in a control "haploid" strain carrying... |
479299 | Characterization of the molecular components in kinetoplast-mitochondrial DNA of Trypanosoma equiperdum. Comparative study of the dyskinetoplastic and wild strains. | The structure of the kinetoplast DNA of Trypanosoma equiperdum has been studied and compared to the structure of the circular mitochondrial DNA extracted from a dyskinetoplastic strain of T. equiperdum. In T. equiperdum wild type, the kinetoplast DNA constitutes approximately 6% of the total cellular DNA and is compose... |
465456 | Heat capacity microcalorimetry of the in vitro reconstitution of calf brain microtubules. | The self-assembly of calf brain tubulin, purified by the modified Weisenberg procedure, was examined in an adiabatic differential heat capacity microcalorimeter. Tubulin solutions at concentrations between 6 and 17 mg/mL were heated from 8 to 40 degrees C at heating rates between 0.1 and 1.0 deg/min in a pH 7.0 phospha... |
458598 | Prostaglandin prodrugs. I: Stabilization of dinoprostone (prostaglandin E2) in solid state through formation of crystalline C1-phenyl esters. | Dinoprostone para-substituted phenyl esters were synthesized in attempt to improve the solid-state stability of the parent prostaglandin. A phenol series covering a wide melting-point range was employed, and a linear relationship was observed between the phenol melting points and the resulting prostaglandin C1-ester me... |
36652 | The in vitro binding of 2,2', 5,5'-tetrachlorobiphenyl metabolites to rat liver microsomal proteins. | The in vitro association of tritium labeled 2,2', 5,5'-tetrachlorobiphenyl (TCB) with the microsomal fraction isolated from rat livers has been investigated in a metabolizing system. It was found that the control microsomes, capable of only minimal TCB metabolism, had 92% of the total microsomal radioactivity associate... |
480469 | In vivo assembly of a biological membrane of defined size, shape, and lipid composition. | At restrictive temperature, mutant ts1 of bacteriophage PM2 makes membrane vesicles inside infected Alteromonas espejiana. A shift from restrictive to permissive temperature resulted in rapid maturation to infectious virions. The membrane vesicles were isolated from cellular membranes by sucrose density gradient centri... |
225539 | Topography of a flexible ribonucleoprotein helix: protein-protein contacts in Sendai virus nucleocapsids. | Contacts among the three polypeptide species in the flexible helical nucleocapsids of a paramyxovirus were examined with bifunctional protein cross-linking reagents. Polypeptides L and P, minor components of Sendai virus nucleocapsids implicated in viral RNA polymerase activity, were efficiently cross-linked into large... |
89089 | Antigenic specificity of neutralizing antibody to cholera toxin. | Selected rabbit antisera to cholera toxin antigens and convalescent cholera patient sera were analyzed using the permeability factor neutralization test and two sensitive in vitro serological assays specific for cholera toxin, cholera toxin A subunit, and cholera toxin B subunit. The results indicated that antisera to ... |
288062 | Kinetics and mechanism of tobacco mosaic virus assembly: direct measurement of relative rates of incorporation of 4S and 20S protein. | The mechanism of assembly of tobacco mosaic virus has been investigated under conditions in which the rates of incorporation of the 4S and 20S proteins can each be directly measured by analytical centfrifugation. Under these conditions, pH 6.5, 6.5 degrees C, 0.10 M ionic strength potassium orthophosphate, the protein ... |
88734 | Noncovalent intermolecular crosslinks are produced by bleomycin reaction with duplex DNA. | Reaction of covalently closed circular PM2 bacteriophage DNA with the anticancer drug bleomycin produces nicked circular (form II) and linear duplex (form III) DNA [Lloyd, R.S., Haidle, C.W. & Robberson, D.L. (1978) Biochemistry 17, 1890-1896]. As the reaction proceeds, the frequencies of both form II and form III DNA ... |
222746 | Formation of a TBA reaction product from crown ether in the presence of KO2. | Potassium superoxide (KO2), which can be dissolved in dimethyl sulfoxide containing crown ether, has been used as a source of O2-. for superoxide reaction systems. We have found that crown ether reacts with thiobarbituric acid (TBA) in the presence of KO2 to form a red pigment, which is a well-known reaction product of... |
457597 | Isolation, characterization, and in vitro assembly of the tetragonally arrayed layer of Bacillus sphaericus. | The tetragonally arranged cell wall layer (T-layer) of Bacillus sphaericus NTCC 9602 was isolated and characterized. Parallel studies were made on a spontaneous variant of the wild-type strain which had a T-layer subunit of altered molecular weight. A purification method for the T-layers was devised which involved sepa... |
457591 | Specific interaction of the tetragonally arrayed protein layer of Bacillus sphaericus with its peptidoglycan sacculus. | Tetragonal layer protein (T-layer) isolated from Bacillus sphaericus NTCC 9602 (wild type) or 9602 Lmw (variant) bonded specifically to the sacculi (peptidoglycan) of either cell type. Only uncleaved T-layer subunits were capable of specific recognition of the B. sphaericus sacculi; other Bacillus strains and gram-posi... |
447803 | Demonstration by radioligand-binding assay of the structural similarity of a partially synthetic growth hormone recombinant molecule to its natural analog and to native human growth hormone. | The recombinant resulting from the noncovalent interaction of a natural amino-terminal fragment of reduced and carbamoylmethylated human GH (residues 1-134) with a synthetic carboxyl-terminal fragment of reduced and carbamoyl-methylated human GH (residues 141-191) reacts in seven immunoassay systems and two receptor as... |
444587 | The dimerization of ferrihaems. IV. Studies on haematoferrihaem and a general appraisal of the nature and implications of dimerization. | The dimerization of haematoferrihaem was studied in phosphate buffer in the pH range 7.02--8.14. The absorbance of dilute solutions decreased over a period of several hours due to adsorption of haematoferrihaem to glass vessels. This problem was overcome by using dilute solutions within 10 min of preparation. Spectroph... |
262414 | The orientational freedom of molecular probes. The orientation factor in intramolecular energy transfer. | The measurement of the efficiency of Förster long-range resonance energy transfer between donor (D) and acceptor (A) luminophores attached to the same macromolecular substrate can be used to estimate the D-A separation, R. If the D and A transition dipoles sample all orientations with respect to the substrate (the isot... |
486083 | The relationship of detergent-solubilization plasma-membrane components of rabbit alveolar macrophages to an isolated inhibitor of phagocytosis. | 1. A plasma-membrane fraction prepared from rabbit alveolar macrophages by hyposmotic borate lysis is described. 2. Rabbit lung lavages, containing a glycoprotein inhibitor of phagocytosis, may be fractionated by preparative isoelectric focusing in the presence of Triton X-100. 3. Chemical analysis indicates that the g... |
38257 | Specific fluorescent labeling of chicken myofibril Z-line proteins catalyzed by guinea pig liver transglutaminase. | Guinea pig liver transglutaminase has been found to catalyze the covalent incorporation of dansylcadaverine into chicken skeletal muscle myofibril proteins. Epifluorescence microscopy reveals that the incorporated dansylcadaverine is specifically localized at or near the myofibril Z line. SDS-polyacrylamide gel electro... |
465550 | [Two possible mechanisms for forming supramolecular structures of the collagen type]. | Comparative electron microscopic investigation of submolecular structure formation of native collagen molecules and denaturated collagen peptides in tropocollagen and gelatin gels was carried out. Submolecular terminal structures were similar. Fibrils exist with cross striation region of 64--70 nm. In spite of this the... |
460204 | [Molecular mechanism of self-assembly of aggregated bacteriochlorophyll c]. | The intermolecular interaction of bacteriochlorophyll c and its pheophytin was studied in nonpolar solvents and solid films with the aid of absorption and infra-red (in the region of 1800--1600 and 3800--3000 cm-1) spectra. The influence of water removing and its addition on these spectra has been investigated. Besides... |
36129 | Resonance Raman investigations of chloroperoxidase, horseradish peroxidase, and cytochrome c using Soret band laser excitation. | Resonance Raman spectra of the heme protein chloroperoxidase in its native and reduced forms and complexed with various small ions are obtained by using laser excitation in the Soret region (350-450 nm). Additionally, Raman spectra of horseradish peroxidase, cytochrome P-450cam, and cytochrome c, taken with Soret excit... |
16592638 | On integral representations for the Neumann operator. | This paper is devoted to the derivation of an approximate formula for the kernel of the Neumann operator N on strongly pseudo-convex domains. In particular, a new class of singular integral operators arises that are infinitely smoothing in the interior and preserve singular supports at the boundary and whose kernels ar... |
16345368 | Bacteria associated with the surface and gut of marine copepods. | Little is known about the nature of bacteria associated with the surface and gut of marine copepods, either in laboratory-reared animals or in the natural environment. Nor is it known whether such animals possess a gut flora. The present report deals with studies of microorganisms isolated from healthy, laboratory-rear... |
88052 | Surface mapping of mouse thymocytes. | The blocking method used previously for determining the relative positions of different components of the cell surface was modified by first fixing the cells with paraformaldehyde. This technique was applied to the H-2K (K), H-2D (D), TL, Lyt-1, and Lyt-2 surface components of mouse thymocytes, and the results were com... |
287005 | Complete amino acid sequence of a histidine-rich proteolytic fragment of human ceruloplasmin. | The complete amino acid sequence has been determined for a fragment of human ceruloplasmin [ferroxidase; iron(II):oxygen oxidoreductase, EC 1.16.3.1]. The fragment (designated Cp F5) contains 159 amino acid residues and has a molecular weight of 18,650; it lacks carbohydrate, is rich in histidine, and contains one free... |
286999 | Isolation of maxicircle component of kinetoplast DNA from hemoflagellate protozoa. | Maxicircle DNA has been isolated from the kinetoplast DNA of Leishmania tarentolae culture forms by bouyant separation in CsCl in the presence of the A + T-binding dye Hoechst 33258, after liberation from the kinetoplast DNA network by cleavage with the single-hit restriction endonuclease EcoRI. The purified linearized... |
262399 | Kinetics of carboxymyoglobin and oxymyoglobin studied by picosecond spectroscopy. | Picosecond studies of carboxymyoglobin (MbCO) and oxymyoglobin (MbO2) reveal that excitation at 530 nm induces photodissociation at less than 8 ps. The kinetic and structural changes were monitored by following absorbance changes at selected wave-lengths in the Soret (B) band and in the Q band. Within the 10 ps-0.45 ns... |
385011 | New aspects of cell membrane radiobiology and their impact on radiation protection. | Recent developments in the field of the membrane biology of eukaryotic cells have revived relevant radiobiological studies. The supramolecular structures of membranes built up by the various chemical components that ensure certain functions and connections of the cells seem to react sensitively to ionizing radiations. ... |
16592629 | Higher plant chloroplasts: Evidence that all the chlorophyll exists as chlorophyll-protein complexes. | By using the polyacrylamide gel electrophoresis system described in this report, it was possible to fractionate all the photosynthetic pigments of maize (Zea mays L.) thylakoids into chlorophyll-protein complexes with negligible formation of free or detergent-complexed chlorophyll. Identical sodium dodecyl sulfate extr... |
379017 | Ultrastructure of microfilament bundles in baby hamster kidney (BHK-21) cells. The use of tannic acid. | After standard glutaraldehyde-osmium tetroxide fixation procedures, the majority of microfilament bundles in BHK-21 cells exhibit relatively uniform electron density along their long axes. The inclusion of tannic acid in the glutaraldehyde fixation solution results in obvious electron density shifts along the majority ... |
286303 | Molecules in mammalian brain that interact with the colchicine site on tubulin. | Colchicine, a plant alkaloid, is a potent inhibitor of mitosis and other physiological processes that involve microtubules. These effects are mediated by the specific binding of colchicine to a high-affinity receptor site on tubulin, the major protein of microtubules. It seemed possible that the colchicine site on tubu... |
436036 | Human somatotropin and lipotropin: relation between structure and activity. | Hormones of the anterior pituitary gland have been divided into three groups according to their chemical and biologic properties. Recent advances in knowledge of the relation between structure and activity of human somatotropin and beta-lipotropin are discussed. |
420814 | An octamer of core histones in solution: central role of the H3-H4 tetramer in the self-assembly. | The association of histones H2A, H2B, H3, and H4 in solution has been studied. In 2 M NaCl and at neutral pH they can assemble in a complex in which each histone is present in equimolar amounts. The complex has a weight average molecular weight of 98,000 (+/- 3700) and a sedimentation coefficient (so20,w) of 4.8. The v... |
572366 | Nucleation of polar actin filament assembly by a positively charged surface. | Polylysine-coated polystyrene beads can nucleate polar assembly of monomeric actin into filamentous form. This nucleation has been demonstrated by a combination of biochemical and structural experiments. The polylysine-coated beads accelerate the rate of actin assembly as detected by two different biochemical assays. S... |
156729 | Chick brain actin and myosin. Isolation and characterization. | Brain actin extracted from an acetone powder of chick brains was purified by a cycle of polymerization-depolymerization followed by molecular sieve chromatography. The brain actin had a subunit molecular weight of 42,000 daltons as determined by co-electrophoresis with muscle actin. It underwent salt-dependent g to f t... |
457745 | The periodic association of MAP2 with brain microtubules in vitro. | Several high molecular weight polypeptides have been shown to quantitatively copurify with brain tubulin during cycles of in vitro assembly-disassembly. These microtubule-associated proteins (MAPs) have been shown to influence the rate and extent of microtubule assembly in vitro. We report here that a heat-stable fract... |
370835 | Origin and direction of DNA replication of plasmid RSF1030. | An in vitro replication system has been used to study the origin and direction of replication of the covalently closed, circular DNA of plasmid RSF1030, a nonconjugative R factor. We have enriched for replicative intermediates in these studies either by isolating them on the basis of their unique structure or by limiti... |
217467 | [Electron microscopic study of isolated proteoglycans]. | Chemically isolated separate preparations of the non-aggregating protein-chondroitin-keratin sulphate (PCKS) fraction from the hyaline cartilage and hyaluronic acid (HUA) of the vitreous body and of the umbilicus were investigated by electron microscopy. PCKS and HUA in films without cytochrome c were present in the fo... |
233024 | Hormone-induced modification of EGF receptor proteolysis in the induction of EGF action. | A proposal that EGF action is mediated through enhanced internalization of EGF receptors is modified to account for more recent evidence. EGF receptors turn over at a rapid rate, and the maintenance of a steady state of EGF receptors on the cell surface is provided through a rapid synthesis of EGF receptors, balancing ... |
550011 | Comparison of the structures of human fibronectin and plasma cold-insoluble globulin. | Human amniotic fluid fibronectin and plasma fibronectin (cold-insoluble globulin) are indistinguishable both immunologically and by amino acid composition. Cyanogen bromide and tryptic peptides also suggest substantial structural homology. However, carbohydrate analysis has demonstrated additional saccharides in fibron... |
575855 | Selective protein transport: characterization and solubilization of the phosvitin receptor from chicken oocytes. | Phosvitin (PV), a subunit of a female-specific protein, vitellogenin, binds to oocyte membranes with a KD of 10(-6) M. Binding reaches equilibrium within 30 min after incubation at 25 degrees C. Bound 125I-PV dissociates from the membrane with a t1/2 of 13 h when incubated in buffer. However, when 125I-PV-labeled membr... |
95125 | Isolation and characterization of the nuclear matrix from the male Xenopus laevis following estrogen administration: kinetics of [3H] uridine incorporation. | At various times following estrogen administration, the nuclear matrix was isolated from the liver of male Xenopus laevis by sucrose gradient centrifugation of nuclei treated with a high-salt buffer and DNase I in the presence of a proteolytic inhibitor (PMSC--phenylmethyl sulfonyl chloride). Electron micrographs of th... |
317717 | Mitogenic effects of murine serum and fibroblast growth factor on EGF nonproliferative variants of 3T3. | The enhanced ability of murine serum to support growth of 3T3 cells, when compared with fetal calf serum, is also evident on variants of 3T3 cells lacking the ability to bind epidermal growth factor (EGF). Variant 3T3 cell lines unable to bind EGF also retain a mitogenic response to fibroblast growth factor. |
550010 | Isolation and characterization of human placental chorionic villar extracellular matrix. | The cell-free extracellular matrix of human placental chorionic villi has been prepared by a procedure employing extraction of the terminal villar fragments with the detergents Triton X-100 and sodium deoxycholate. The isolated human placental extracellular matrix retains an intact, but collapsed, histoarchitecture, as... |
398910 | Sequence of the amino-terminal region of rat liver ribosomal proteins S4, S6, S8, L6, L7a, L18, L27, L30, L37, L37a, and L39. | The sequence of the amino-terminal region of eleven rat liver ribosomal proteins--S4, S6, S8, L6, L7a, L18, L27, L30, L37a, and L39--was determined. The analysis confirmed the homogeneity of the proteins and suggests that they are unique, since no extensive common sequences were found. The N-terminal regions of the rat... |
317716 | Rhodopsin phosphorylation suggests biochemical heterogeneities of retinal rod disks. | Frogs (Rana pipiens) were injected subcutaneously with (3H)-leucine and allowed to incorporate the radioactive amino acid into newly assembled disks in the retinal rod outer segment. The labeled disks served as a temporal marker for following the turnover of rod outer segments. Animals were killed at different times af... |
95025 | Fibronectin associated with the glial component of embryonic brain cell cultures. | In the basic approach to investigations of neuronal--glial interactions during both normal brain development and its pathogenesis, embryonic brain cell populations were fractionated into purified neuronal and glial components. Using separation procedures based on differential adhesion and cytotoxicity, the isolated neu... |
232892 | Isolation and characterization of a variant of B16-mouse melanoma resistant to MSH growth inhibition. | A variant of B-16 F1 mouse melanoma was selected for its ability to survive and replicate in the presence of melanocyte-stimulating hormone (MSH). Although the variant (MR-4) was completely resistant to growth inhibition of MSH, cyclic AMP was still able to block cell replication. Tyrosinase activity in MR-4 cells was ... |
121318 | Influence of buffer ions and divalent cations on coated vesicle disassembly and reassembly. | Disruption of the coat of coated vesicles is accompanied by the release of clathrin and other proteins in soluble form. The ability of solubilized coated vesicle proteins to reassemble into empty coats is influenced by Mg2+, Tris ion concentration, pH, and ionic strength. The proteins solubilized by 2 M urea spontaneou... |
548650 | Inhibition of blood coagulation factor XIIIa-mediated cross-linking between fibronectin and collagen by polyamines. | Soluble fibronectin is found in body fluids and media of cultured adherent cells. Insoluble fibronectin is found in tissue stroma and in extracellular matrices of cultured cells. Fibronectin is a substrate for factor XIIIa (plasma transglutaminase) and can be cross-linked to collagen and to the alpha chain of fibrin. W... |
575786 | Human fibrosarcoma cells produce fibronectin-releasing peptides. | A sensitive radioimmunoassay, specific for human fibronectin, was used to measure the ability of certain biologically active polypeptides to release fibronectin from cultured human lung fibroblasts into their culture media. Concentrated, serum-free supernatant from a human fibrosarcoma cell line was fractionated by gel... |
232891 | Growth of kidney epithelial cells in hormone-supplemented, serum-free medium. | Madin Darby canine kidney cells can grow in synthetic medium supplemented with 5 factors--insulin, transferrin, prostaglandin E1, hydrocortisone and triiodothyronine--as a serum substitute. These 5 factors permit growth for one month in the absence of serum, and a growth rate equivalent to that observed in serum-supple... |
575785 | Pyrimidine biosynthesis in normal and transformed cells. | We have developed procedures for sensitive measurement of specific radioactivities of pyrimidine nucleosides excreted from cells in culture. The changes in the observed values reflect dilution of the added isotope through de novo biosynthesis of nonradioactive pyrimidine nucleosides or by shifting and equilibration of ... |
44891 | Mitotic factors from mammalian cells: a preliminary characterization. | The objective of this study was the preliminary characterization of the factors from mitotic HeLa cells that can induce meiotic maturation in Xenopus laevis oocytes. We found that this factor is a heat-labile, Ca2+-sensitive, nondialyzable protein with a sedimentation value of 4-5S. Furthermore, no new protein synthesi... |
398429 | Growth control by cell to cell contact. | Control of cell growth by cell to cell contact is reviewed with particular emphasis on two systems--contact inhibition of growth observed with Swiss 3T3 cells and the mitogenic stimulation of Schwann cells by dorsal root ganglia neurites. In both cases the biological effect can be reproduced by the addition of surface ... |
398428 | The detection, immunofluorescent localization, and thrombin induced release of human platelet-associated fibronectin antigen. | Platelets are cells which develop adhesive properties following stimulation. Since fibronectin (fn) mediates adhesive properties of several cells, we sought evidence for platelet associated fn. Lysates of suspensions of washed human platelets containing less than or equal to 50 ng soluble fn/10(9) cells contained 2.85 ... |
398427 | Properties of epithelial cells cultured from human carcinomas and nonmalignant tissues. | Human epithelial cell cultures were examined for expression of plasminogen activator and fibronectin matrix. All of the cells examined showed ultrastructural evidence suggesting their epithelial origin, including microvilli and specialized junctions. The nonmalignant cells were also negative for endothelial cell marker... |
44890 | NMR of fd coat protein. | The conformations of the major coat protein of a filamentous bacteriophage can be described by nuclear magnetic resonance spectroscopy of the protein and the virus. The NMR experiments involve detection of the 13C and 1H nuclei of the coat protein. Both the 13C and 1H nuclear magnetic resonance (NMR) spectra show that ... |
95024 | The assembly of lipid-linked oligosaccharides in plant and animal membranes. | Membrane preparations from growing regions of pea stems and actively-dividing mouse L-cells form lipid-linked saccharides from GDP-mannose and UDP-N-acetylglucosamine. These lipids have properties which are consistent with those of mono- and di-phosphoryl polyisoprenyl derivatives. In experiments using plant membranes,... |
161993 | A high-affinity ATP-binding site on 30S dynein. | The enhancing effect of low concentrations (eg, 8 microM) of bis(4-fluoro-3-nitrophenyl)sulfone (FNS) on 30S dynein ATPase activity is increased when 1 mM dithiothreitol (DTT) is present. The effect of FNS + DTT is optimal at pH 7.5. Activation of the latent ATPase activity of 30S dynein by FNS + DTT is partially preve... |
547231 | Molecular recognition of nucleotides by means of ionic interaction in hydrophobic media. | Adenosine phosphates, AMP, ADP and ATP were found to be recognized and extracted from aqueous to an organic phase by the newly prepared lipophilic diammonium salt, N,N'-distearyldiammonium dichloride of 1,4-diazabicyclo [2.2.2] octane 1. ADP and ATP were specifically bound by 1 under the condition of no appreciable bin... |
547119 | Analysis of transmembrane proteins from eukaryotic cells. | The topography and properties of plasma membrane proteins from mouse L-929 cells are studied by comparing their availability for enzymatic labeling on the external and internal surfaces of the membrane. In order to study the internal surface, phagolysosomes are prepared from cells after they ingest latex particles. The... |
94933 | Tumor-associated antigenic differences between the primary and the descendant metastatic tumor cell populations. | The existence of antigenic differences between cell populations in the local growth of the 3LL tumor (L-3LL) and its lung metastases (M-3LL) was studied. Normal C57BL/6 spleen cells sensitized in vitro for 5 days against L-3LL monolayers lysed preferentially L-3LL targets but not M-3LL tumor cell targets. Conversely, a... |
397975 | The regional association of actin and myosin with sites of particle phagocytosis. | Contractile proteins are thought to play a causative role in motile processes such as phagocytosis. In order to investigate their role in phagocytosis further, simultaneous immunofluorescence localization of F-actin and myosin was carried out in resident mouse peritoneal macrophages after phagocytosis of opsonized zymo... |
232736 | Alteration of human breast tumor cell membrane functions by chromosome-mediated gene transfer. | BOT-2 cells (human breast tumor origin) have an impaired ability to utilize exogenous thymidine. Previous studies revealed this deficiency to be the permeation event rather than phosphorylation, since the cells have active thymidine kinase. Chromosome-mediated gene transfer was used to transfer genetic information in t... |
232735 | Role of the microfibrillar system in knob action of transformed cells. | Transformed cells often display knobs (or blebs) distributed over their surface throughout most of interphase. Scanning electron microscopy (SEM) and time-lapse cinematography on CHO-K1 cells reveal roughly spherical knobs of 0.5-4 micron in diameter distributed densely around the cell periphery but sparsely over the c... |
547118 | alpha-bungarotoxin binding sites (acetylcholine receptors) in denervated mammalian sarcolemma. | The nonsynaptic sarcolemma of denervated skeletal muscle of rat shows an abundance of approximately 15 nm intramembranous particles on the P face. These particles are either singly distributed or are in clusters, and they are essentialy lacking from the comparable freeze-fractures of the innervated sarcolemma. Autoradi... |
397974 | Protein-RNA interactions during TMV assembly. | A review of the structural studies of tobacco mosaic virus (TMV) is given. TMV is essentially a flat helical microcrystal with 16 1/3 subunits per turn. A single strand of RNA runs along the helix and is deeply embedded in the protein. The virus particles form oriented gels from which high-resolution X-ray fiber diffra... |
121144 | Gliding mycoplasmas are inhibited by cytochalasin B and contain a polymerizable protein fraction. | Studies are presented on the effect of cytochalasin B (CB) on the growth of five Mycoplasma species, three Acholeplasma species, and one Spiroplasma species. The three gliding mycoplasma species (M gallisepticum, M pneumoniae and M pulmonis are the only mycoplasmas inhibited by CB. These are the only prokaryotes report... |
547117 | Scanning electron microscopy of differentiated liver cells transformed in vitro by chemical carcinogens. | A scanning electron microscopy study was carried out on differentiated liver cells transformed in vitro by three chemical carcinogens into cells that give rise to carcinomas. The results indicate that the transformed cells grow as a rule in tightly adherent monolayers but differ in topography. There is a tendency towar... |
544939 | Isolation of cholera toxin receptors from a mouse fibroblast and lymphoid cell line by immune precipitation. | Cholera toxin receptors have been isolated from both a mouse fibroblast (Balbc/3T3) and mouse lymphoid cell line labeled by the galactose oxidase borotritiide technique. Tritiated receptor-toxin complexes solubilized in NP40 were isolated by addition of toxin antibody followed by a protein A-containing strain of Staphy... |
232529 | Regulation of dome formation in differentiated epithelial cell cultures. | Rat mammary (Rama 25) and dog kidney (MDCK) epithelial cell cultures formed 'domes' of cells due to fluid accumulation in focal regions between the culture dish and the cell monolayer. Addition of ouabain caused collapse of domes, suggesting that transport functions were required for maintenance of domes. Dome formatio... |
544938 | Direct linkage of thrombin to its cell surface receptors in different cell types. | When 125I-thrombin was incubated with foreskin fibroblasts, cervical carcinoma cells or fibrosarcoma cells of human origin, or with secondary chick embryo cells or Chinese hamster lung cells, it became directly linked to its cell surface receptors. The thrombin-receptor complex (TH-R) was derived exclusively from a poo... |
544937 | Introduction of metastatic heterogeneity by short-term in vivo passage of a cloned transformed cell line. | An experimental system for the study of metastasis has been developed using an epithelioid cell line of hepatic origin which had previously been chemically transformed in vitro. These metastatic cells were studied in the syngeneic rat strain. The cloned parent cell line metastasizes only to the lungs following intraven... |
544936 | Biosynthesis and maturation of cellular membrane glycoproteins. | The biosynthesis and the processing of asparagine-linked oligosaccharides of cellular membrane glycoproteins were examined in monolayer cultures of BHK21 cells and human diploid fibroblasts after pulse- and pulse-chase labeling with [2-3H]mannose. After pronase digestion, radiolabeled glycopeptides were characterized b... |
397370 | Action of phorbol esters in cell culture: mimicry of transformation, altered differentiation, and effects on cell membranes. | The carcinogenic process is usually multifactor in its causation and multistep in its evolution. It is likely that entirely different molecular mechanisms underlie the many steps in this process. In contrast to initiating carcinogens, the action of the tumor-promoting phorbol esters does not appear to involve covalent ... |
120908 | 7-Acetylcytochalasin B: differential effects on sugar transport and cell motility. | Cytochalasin B (CB) is a potent inhibitor of sugar transport and cell motility in animal cells. We have synthesized and characterized the CB derivative 7-acetylcytochalasin B (CBAc) and have found that it has differential effects on transport and motile processes in fibroblasts. The derivative inhibited sugar transport... |
544935 | Structural comparisons of the aggregates of tobacco mosaic virus protein. | The coat protein of tobacco mosaic virus forms numerous aggregates, including the small A-protein, the disk, and two helical forms. The structures of the disk, the helical protein forms, and the virus are compared. Most of the differences are in the conformation of the chain between residues 89 and 113, which lies in t... |
397369 | Evidence of microfilament-associated mitochondrial movement. | The mitochondria in the lower Malpighian tubule of the insect Rhodnius prolixus can be stimulated by feeding in vivo and by 5-hydroxytryptamine in vitro, to move from a position below the cell cortex to one inside the apical microvilli. During and following their movement into the microvilli, the mitochondria are intim... |
544934 | Biosynthesis of membrane glycoproteins in rat hepatoma tissue culture cells. | The early steps in the biosynthesis of glycoproteins associated with the plasma membranes of rat hepatoma tissue culture cells has been analyzed. By measuring the effect of tunicamycin on the incorporation of [3H] mannose and [3H] fucose into cell glycoproteins, it was determined that an interval of about 1 h was requi... |
232528 | Structural and functional alterations in the surface of vascular endothelial cells associated with the formation of a confluent cell monolayer and with the withdrawal of fibroblast growth factor. | Vascular endothelial cells cultured in the presence of fibroblast growth factor (FGF) divide actively when seeded at low or clonal cell densities and upon reaching confluence adopt a morphologic appearance and differentiated properties similar to those of the vascular endothelium in vivo. In this review, we present som... |
232527 | Effects of the tumor promoter TPA on the induction of DNA synthesis in normal and RSV-transformed rat fibroblasts. | Induction of DNA synthesis by the tumor promoter tetradecanoyl phorbol acetate (TPA) was studied in a line of cultured rat fibroblasts (Rat-1) and their Rous sarcoma virus-transformed derivative (Rat-1 (RSV)). Following serum deprivation for 54 h to achieve quiescence, semiconservative DNA replication was measured by i... |
544933 | Membrane dynamics of differentiating cultured embryonic chick skeletal muscle cells by fluorescence microscopy techniques. | Changes in membrane fluidity during myogenesis have been studied by fluorescence microscopy of individual cells growing in monolayer cultures of embryonic chick skeletal muscle cells. Membrane fluidity was determined by the techniques of fluorescence photobleaching recovery (FPR), with the use of a lipid-soluble carboc... |
94615 | The errors in assembly of MuLV in interferon treated cells. | Interferon treatment of JLSV-6 cells chronically infected with Rauscher MuLV leads to the formation of noninfectious particles (interferon virions) containing the structural proteins of env and gag genes as well as additional viral polypeptides. In the control virions the major glycoprotein detected is gp71, interferon... |
161792 | Effect of thiourea and substituted thioureas on dynein ATPase and on the turbidity response of Tetrahymena cilia. | The effects of thiourea and of several substituted thioureas -- phenylthiourea, alpha-naphtylthiourea, metiamide, and burimamide -- on dynein ATPase have been studied. The substituted thioureas are over 30 times more potent than thiourea in causing enhancement of 30S dynein ATPase activity and inhibition of 14S dynein ... |
120907 | Glycosaminoglycans of the plasma membranes of renal tubule and liver cells. | Glycosaminoglycans were isolated from plasma membranes of hepatic and renal tubule cells of guinea pig. Plasmalemma of renal tubule cells contained more total glycosaminoglycans, hyaluronic acid, chondroitin-4 sulfates and chondroitin-6 sulfates, and less dermatan sulfates and heparin sulfates than liver plasma membran... |
397368 | Possible role of fibronectin in malignancy. | Frozen sections of tumors induced by injecting virally transformed cells into animals were stained for fibronectin by immunofluorescence. Many tumor cell lines do not express fibronectin in tumors in situ even though some of them express fibronectin in culture. Cell shape and hormones appear to influence the expression... |
232526 | Polyoma T (tumor) antigen species in abortively and stably transformed cells. | Stable neoplastic transformation of cells by polyoma virus requires the particpation of two viral genes, designated ts-a and hr-t. The effects of mutations in these two genes on the patterns of T-antigen synthesis during productive infection have been previously described: ts-a mutants are affected in the "large" (100K... |
544932 | Ehrlich ascites tumor cell surface labeling and kinetics of glycocalyx release. | Ehrlich ascites tumor cells spontaneously release cell surface material (glycocalyx) into isotonic saline medium. Exposure of these cells to tritium-labeled 4,4'-diisothiocyano-1,2-diphenylethane-2,2'-disulfonic acid (3H2DIDS) at 4 degrees C leads to preferential labeling of the cell surface coat. We have combined stud... |
544931 | Structural states of dictyostelium myosin. | Myosin purified from Dictyostelium amoebae has approximately 10% by weight of RNA associated with it, unless specific steps (DEAE cellulose chromatography or RNase digestion) are taken to remove it. This RNA has significant effects on the structural states formed by the myosin at low ionic strength in the presence of M... |
232525 | Modulation of cell surface iron transferrin receptors by cellular density and state of activation. | This report describes investigations of plasma membrane transferring receptors on a variety of lymphoid cell lines and normal peripheral blood lymphocytes during activation and cell growth cycles. Transformed lymphoid cell lines have as many as 1,000 times the number of receptors found on normal resting lymphocytes. Th... |
544930 | Production of monoclonal antibodies against a cell surface concanavalin A binding glycoprotein. | Concanavalin A-binding (Con-A)-binding cell surface glycoproteins were isolated, via Con A-affinity chromatography, from Triton X-100-solubilized Chinese hamster ovary (CHO) cell plasma membranes. The Con A binding glycoproteins isolated in this manner displayed a significantly different profile on sodium dodecyl sulfa... |
232524 | Alteration of insulin binding and cytoskeletal organization in cultured fibroblasts by tertiary amine local anesthetics. | Tertiary amine local anesthetics cause a time- and dose-dependent, reversible increase in insulin binding sites in cultured chick embryo fibroblasts. Incubation of fibroblasts with 0.2 mM dibucaine for 3 h at 37 degrees C results in a twofold to threefold increase in insulin binding, with an increase in average number ... |
232523 | Tumorigenicity of revertant from an SV40-transformed line. | A syndrome of in vitro properties correlates with the tumorigenicity of SV40-transformed rodent cells. These properties are: plasminogen activator production, loss of large actin cables, and anchorage-independent growth. An established rat fibroblast line, its SV40 transformant, several T-antigen negative revertants, a... |
397367 | Growth control of normal and transformed cells. | Both serum factors and protein synthesis are required for normal cell growth. Swiss 3T3 cells require the serum growth factors insulin and EGF (epidermal growth factor) during the initial part of the G1 period, until they pass a restriction point about 2 h before the initiation of DNA synthesis. Concentrations of cyclo... |
544929 | Selection of malignant melanoma variant cell lines for ovary colonization. | Murine melanoma line B16-F1, which shows some specificity for metastatic organ colonization of lung but rarely metastasizes to ovary, was used to select variant cell lines with increased preference for experimental ovary metastasis. Ovary-colonizing melanoma cell lines were sequentially selected in syngeneic C57BL/6 mi... |
544928 | Human placental cell surface antigens:expression by cultured cells of diverse phenotypic origin. | The present work examined the expression of cell surface glycoprotein antigens in cultured human cell lines. The set of glycoproteins studied was defined by their immunoreactivity with antiserum developed to Triton-solubilized extracts of placental brush border membranes. Studies were performed using cell lines of trop... |
544927 | Lectin affinity chromatography of cell surface proteins of Novikoff tumor cells. | Novikoff hepatocellular carcinoma cells were radioiodinated by a cell surface-specific method using lactoperoxidase/125I. The iodinated proteins were solubilized in 0.5% Nonidet P-40 and subjected to affinity chromatography on Sepharose-conjugated lectins (Ricinus communis agglutinins I or II, soybean agglutinin, conca... |
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