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Query: UNIPROT:Q07644 (polypeptide)
 72,197 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The calcium transport ATPase (M(r) 100,000) from sarcoplasmic reticulum membranes was synthesized in a cell-free translation system containing rough microsomes or detergent-treated bound polysomes from 14- to 16-day old chicken embryo muscles. Immunoprecipitates obtained from total translation mixtures treated with anti-ATPase antiserum contained 1.5% of the total radioactivity incorporated in vitro. A polypeptide with the electrophoretic mobility, isoelectric point, and [(35)S]methionine-labeled tryptic peptide pattern of the mature ATPase was a major component of these immunoprecipitates. By contrast, free polysomes from the same source, which were capable of high levels of in vitro protein synthesis, did not yield immunoprecipitable ATPase. ATPase synthesized in rough microsomes was not released by treatment with 10 mM EDTA in a high-salt medium (0.5 M KCl) which removes ribosomes and peripheral membrane proteins. Furthermore, labeled ATPase remained associated with the microsomes after these were treated with low concentrations of deoxycholate (0.1 mg/mg of protein in 0.3 ml) which release the luminal content of the vesicles. Only with higher deoxycholate concentrations (0.5 mg/mg of protein in 0.3 ml), which cause membrane dissolution, was the labeled ATPase found on the detergent extracts. These observations indicate that newly synthesized ATPase discharged from bound ribosomes is transferred directly to the sarcoplasmic reticulum membranes where it is incorporated as an integral membrane protein.
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PMID:In vitro synthesis of the Ca2+ transport ATPase by ribosomes bound to sarcoplasmic reticulum membranes. 15 18

At least three groups of polypeptides of the inner membrane of rat liver mitochondria have been shown to be exposed to the exterior surface by several techniques: lactoperoxidase-catalyzed iodination of mitochondria and inner membrane/matrix vesicles (mitoplasts), reaction of mitochondria and mitoplasts with the membrane-impermeable diazonium salt of sulfanilic acid, and controlled proteolysis of mitoplasts. These classes of proteins, separated by dodecyl sulfate gel electrophoresis, have polypeptide molecular weights of 73,000, 31,000, and 26,000. In addition, four other groups have been shown to be exposed to the exterior surface by at least one of these techniques: these components have polypeptide molecular weights of 130,000, 87,000, 16,000, and 10,500. A class of proteins, which makes up 50 to 60% of the total mitochondrial protein and which can be easily extracted from mitoplasts by freeze-thaw fractionation or other procedures designed to separate "matrix" protein from "membrane" protein, is shown not to be exposed to the outer surface of the inner membrane by these techniques. This class of proteins contains polypeptides of various molecular weights and includes the major 165,000 molecular weight polypeptide, identified with carbamyl phosphate synthetase.
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PMID:Protein asymmetry in the inner membrane of rat liver mitochondria. 17 48

Two forms of yeast RNA polymerase A are resolved by phosphocellulose chromatography. One of these, called RNA polymerase A, is lacking two polypeptide chains of 48,000 and 37,000 daltons. The properties of the two enzymes are compared in the present paper. RNA polymerase A transcribes d(A-T)n with a similar efficiency as the complete enzyme, but it is comparatively much less active with native DNA. The two enzymes can also be differentiated on the basis of their ionic strength and divalent cation requirements. RNA polymerase A has a particularly low activity at high salt and low Mg2+ concentrations. Thermal inactivation curves of the two enzymes are different when residual activity is assayed with native DNA. In contrast with d(A-T)n as template the apparent inactivation curves of the two enzymes are identical. The data suggest that the two dissociable polypeptide chains play an important role in transcription. The template specificity of yeast RNA polymerase B was further investigated using SV40 DNA-FI as template. RNA polymerase B is able to retain [3H]SV40 DNA-FI on nitrocellulose filters but the enzyme-DNA complex is very unstable. The observation that RNA polymerase B can transcribe to some extent a supercoiled DNA but not a linear double stranded template supports the hypothesis that the enzyme needs some unpaired DNA structure to initiate transcription.
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PMID:Further characterization of yeast RNA polymerases. Effect of subunits removal. 18 85

The glyceraldehyde 3-phosphate dehydogenase holoenzyme of Bacillus stearothermophilus possesses precise 222 symmetry: in this respect it differs from the reported structure of the lobster muscle enzyme. Pairs of active sites are linked through a flexible polypeptide loop which probably mediates the structural changes giving rise to cooperative effects. Three additional salt bridges made by each subunit to others would make a major contribution to thermostability of the tetramer.
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PMID:Sequence and structure of D-glyceraldehyde 3-phosphate dehydrogenase from Bacillus stearothermophilus. 19 30

Synthesis of cytoplasmic DNA-binding proteins was investigated after a shift from the nonpermissive to the permissive temperature in NRK cells transformed by a temperature-sensitive mutant of Rous sarcoma virus [ts339(RSV)]. Cells were labeled for several generations in [3H]leucine and were pulse-labeled with [35S]methionine for 1 h at the nonpermissive temperature (39 degrees C) and at the permissive temperature (33 degrees C, 5 h after shift from 39 degrees C). Proteins binding to sequential columns of double-stranded and single-stranded DNA-cellulose were examined by polyacrylamide gel electrophoresis in the presence of sodium dodecyl sulfate, and the 35S/3H ratios were obtained for each column fraction and for individual polypeptides. The protein fractions binding to single-stranded, but not double-stranded, DNA and eluting at high salt concentrations (greater than 0.60 M NaCl) showed elevated 35S/3H ratios. This indicated increased synthesis of these proteins within 5 h after the onset of transformation. The majority of the polypeptides in these fractions showed increased synthesis as a consequence of transformation. One prominent polypeptide among them constituted 0.1% of the cytosol protein and had a molecular weight of 93,000. We conclude that the synthesis of proteins binding tightly to single-stranded DNA is increased early after the onset of transformation.
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PMID:Changes in synthesis of DNA-binding proteins during the onset of transformation in NRK cells transformed by a temperature-sensitive mutant of Rous sarcoma virus. 19 62

Polypeptide synthesis in three different cell types infected with simian virus 5 has been examined using high-resolution polyacrylamide slab gel electrophoresis, and all of the known viral polypeptides have been identified above the host cell background. The polypeptides were synthesized in infected cells in unequal proportions, which are approximately the same as they are found in virions, suggesting that their relative rates of synthesis are controlled. The nucleocapsid polypeptide (NP) was the first to be detected in infected cells, and by 12 to 14 h the other virion structural polypeptides were identified, except for the polypeptides comprising the smaller glycoprotein (F). However, a glycosylated precursor (F(0)) with a molecular weight of 66,000 was found in each cell type, and pulse-chase experiments suggested that this precursor was cleaved to yield polypeptides F(1) and F(2). No other proteolytic processing was found. In addition to the structural polypeptides, the synthesis of five other polypeptides, designated I through V, has been observed in simian virus 5-infected cells. One of these (V), with a molecular weight of 24,000, was found in all cells examined and may be a nonstructural viral polypeptide. In contrast, there are polypeptides present in uninfected cells that correspond in size to polypeptides I through IV, and similar polypeptides have also been detected in increased amounts in cells infected with Sendai virus. These findings, and the fact that the synthesis of all four of these polypeptides is not increased in every cell type, suggest that they represent host polypeptides whose synthesis may be enhanced upon infection. When a high salt concentration was used to decrease host cell protein synthesis in infected cells, polypeptides IV and (to a lesser extent) I were synthesized in relatively greater amounts than other cellular polypeptides, as were the viral polypeptides. The possibility that these polypeptides may play some role in virus replication is discussed.
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PMID:Polypeptide synthesis in simian virus 5-infected cells. 19 1

During the different stages of granuloma formation peptidyl prolyl hydroxylase activity and neutral salt soluble collagen were determined in the granuloma tissue. In parallel peptidyl prolyl hydroxylase activity, "collagen-like protein", and free hydroxyproline were measured in the serum of the same animals at correspondant time distances. A close correlation was found between the enzyme activity and the other parameters of collagen synthesis. These results confirm the conclusion that hydroxylation of polypeptide may be a rate limiting step in collagen biosynthesis. In addition the investigations revealed a close correlation between enzyme activity in the tissue and enzyme activity in the serum.
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PMID:[Peptidyl prolyl hydroxylase activity in relation to the actual collagen biosynthesis in cotton pellet granuloma of guinea pig (author's transl)]. 19 77

Human serum high density lipoprotein subfractions 2 and 3, isolated by preparative ultracentrifugation after blocking the enzyme phosphatidylcholine: cholesterol acyl transferase, have been subfractionated further by hydroxyapatite column chromatography. From subfraction 2 we reproducibly obtained 5 and from subfraction 3, 6 fractions differing in chemical composition and apolipoprotein content. The fractions eluting at low salt concentrations were composed primarily of apolipoprotein-A polypeptides while those eluting at high salt concentrations consisted primarily of apolipoprotein-C. From all the 11 subfractions only one contained the "arginine-rich" polypeptide. The apolipoprotein-C-containing fractions were richer in triacylglycerol, phospholipids and free cholesterol as compared to the apolipoprotein-A-containing ones. Although small differences of their partial specific volumes existed, the obtained values indicate that all subfractions belonged to the parent density class. The implications of these results to the current view of lipoprotein metabolism are discussed.
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PMID:The separation of human serum high density lipoproteins by hydroxy apatite column chromatography. Evidence for the presence of discrete subfractions. 19 4

Synthesis of cellular protein was substantially inhibited within 1 h of infection with herpes simplex virus, type 2, strain G (HSV-2). The inhibition also occurred, although no virus-specific protein synthesis was detected, after infection with u.v. irradiated virus and in cytoplasts that had been enucleated before infection. The inhibitory activity could not be distinguished from infectivity by dilution, sedimentation or reaction with gamma-globulin. HSV-2 also suppresssed the synthesis of Sendai virus proteins, but not those specified by HSV-1. Host protein synthesis was no more sensitive than virus protein synthesis to an increased concentration of NaCl in the medium, nor could the suppression of host synthesis be prevented by adding excess MgCl2 to the medium or by omitting CaCl2 or NaCl. It was accompanied by the breakdown of polyribosomes, which also occurred in the presence of cycloheximide but not at 4 degrees C. The breakdown yielded ribosomes that were sensitive to a high salt concentration, unlike those produced by treatment of polyribosomes with RNase. The synthesis of cellular DNA and RNA was also inhibited following infection with u.v.-inactivated virus. It is concluded that the suppression of host protein synthesis (and probably also of host DNA and RNA synthesis) is caused by a constituent of the infecting virus particles. The mechanism is obscure but probably does not depend on the leakage out of the cell of Mg2+ or into the cell or Ca2+ or Na+ ions, nor on the specific inhibition of initiation of host polypeptide chains, nor on RNase-like attack on host polyribosomes.
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PMID:Suppression of the synthesis of cellular macromolecules by herpes simplex virus. 21 20

The complete primary structure of the cytoplasmically synthesized polypeptide IV from beef heart cytochrome oxidase was determined via isolation and sequencing of overlapping methionine, tryptophan, and arginine fragments. The protein consists of 147 amino acids (Mr 17153). It is characterized as a part of a membrane protein complex by a hydrophobic segment consisting of 19 residues. It is suggested that this segment contacts the lipids of the inner mitochondiral membrane. Additional specific contacts may result from pairwise formation of salt bridges between ionic groups of the protein and the phospholipids. The function of this component of the terminal oxidase is yet unknown.
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PMID:Studies on cytochrome c oxidase, VI. Polypeptide IV. the complete primary structure. 22 80


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