Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:Q07644 (polypeptide)
 72,197 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Pulse-chase labeling and cell fractionation were used to examine the pathways taken by the three nucleocapsid polypeptide species of vesicular stomatitis virus into nucleocapsids and then into virions. An improved method of polyacrylamide gel electrophoresis resolved nucleocapsid polypeptides N and NS from cellular actin, facilitating accurate quantitation of the viral polypeptides. Contrary to previous belief, the rate of NS synthesis was found to be a constant fraction of total virus protein synthesis throughout infection, indicating a consistent mechanism of virus protein synthesis regulation. In the kinetic studies, each polypeptide species displayed the following characteristic behavior. (i) Structural polypeptide N was the only species that entered a metabolically active soluble pool before assembly into nucleocapsids. The size of this pool increased with time after infection, causing an increasing delay in the appearance of pulse-labeled N molecules in nucleocapsids. (ii) Throughout infection, the entire complement of L molecules entered nucleocapsids immediately after their synthesis, without diversion through a soluble pool. (iii) Although 75% of newly synthesized molecules of the transcriptase-associated protein NS entered a soluble pool, they never emerged from the compartment. At all times after infection, about 25% of the NS molecules bypassed the soluble pool and entered nucleocapsids directly after their synthesis, as if in concert with L. These results indicate that VSV nucleocapsid assembly in vivo is a stepwise process, comprising an initial condensation of N with the viral RNA, followed by attachment of L and NS, analogous to the stepwise assembly of Sendai virus nucleocapsids. (D. W. Kingsbury, C.-H. Hsu, and K. G. Murti. Virology 91:86-94, 1978). About half of the intracellular nucleocapsids were recovered in a form that sedimented at anomalously low centrifugal forces, reflecting an association with large cellular organelles. This attachment was mediated mainly by electrostatic forces, since these "bound" nucleocapsids were released by elevated salt concentrations. The kinetic behavior of nucleocapsid polypeptides was the same in both fractions, providing no evidence for a division of nucleocapsid functions between cellular compartments.
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PMID:Assembly of vesicular stomatitis virus nucleocapsids in vivo: a kinetic analysis. 23 81

The 220-MHz high-resolution proton magnetic resonance (PMR) spectrum of histone IV has been examined as a function of histone concentration, salt concentration, and pD. The hydrophobic C-terminal portion of the histone IV monomer appears to be largely PMR "invisible" indicating that this region of the polypeptide contains rigid secondary structure. Further loss of PMR resonance areas with increased histone IV concentration in neat D2O has been attributed to self-aggregation involving a monomer-dimer equilibrium. An equilibrium between the monomer and large aggregates, on the other hand, appears to dominate at NaCl concentrations above 0.01 M. pD studies reveal an abrupt increase in histone IV aggregation at pD smaller than 0.8 and precipitation of histone IV at pD values in the neighborhood of its isoelectric point, pD similar to 11.
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PMID:Nuclear magnetic resonance studies of histone IV solution conformation. 23 81

Highly purified Sendai virus contained a protein kinase activity which atatlysed the phosphorylation of endogenous polypeptides or exogenous protamine sulphate. The virus contained very low levels of phosphoprotein phosphatase activity. Polyacrylamide gel analysis of the reaction product indicated that the phosphorylation was specific for certain polypeptides and varied according to whether the virus was grown in eggs or in tissue culture. This variation was partially associated with the difference in the polypeptide pattern that occurred when the virus was grown in eggs or in tissue culture. Characterization of these phosphoproteins demonstrated that the phosphate was incorporated predominantly in a phosphoester linkage with theonine residues. Using a detergent and high salt solubilization procedure, the protein kinase activity was found associated within glycoprotein free virus particles but not with the nucleocapsid-associated polypeptides. In vivo phosphorylation occurred when Sendai virus was grown in eggs or in tissue culture with [32P] and the phosphorylated polypeptides were similar to those of the protein kinase reaction product. Phosphorylation could also be detected in the infected cell and could occur once the virus particle polypeptides were being synthesized. The non-structural polypeptides were not phosphorylated.
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PMID:The phosphorylation of sendai virus proteins by a virus particle-associated protein kinase. 23 97

Different conformations of polypeptides were characterized by measurements of the circular dichroism (CD) extended into the vacuum ultraviolet region. (i) The linear beta-pleated sheet structure was characterized in a broad ultraviolet region down to 165 nm by examination of copolypeptides composed of alternating hydrophobic and hydrophilic amino-acid residues, e.g., poly(Lys-Leu-Lys-Leu). A short-wavelength intense band was found at about 169 nm, which is characteristic of beta-pleated sheet conformation. (ii) The beta-turns were experimentally measured using poly(Ala(2)-Gly(2)) in a broad spectral region down to 165 nm with accuracy. The observed CD spectrum is in excellent qualitative agreement with the theoretical curve calculated by Woody for the beta-turns of type II and/or I of Venkatachalam. The similarity in shape between the theoretical curve and the observed CD spectra suggests a dominance of beta-turn segments in the poly(Ala(2)-Gly(2)) structure. The presence of beta-turns in poly(Ala(2)-Gly(2)) is also in agreement with the characterization of this polypeptide by solid state methods (electron microscopy and x-ray diffraction). The CD spectrum of beta-turns is characterized by a very intense band at 207.5 nm and strong negative bands at 191 and 169 nm. Copolypeptides such as poly(Ala(2)-Gly(3)) and poly(Ala(3)-Gly(3)) yielded a similar type of CD spectrum, analysis of which indicates that a large fraction of their residues is contained in beta-turn regions. (iii) The CD spectrum of the unordered chain of these alternating copolypeptides in salt-free solution is observed in the vacuum ultraviolet region.
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PMID:Identification of beta,beta-turns and unordered conformations in polypeptide chains by vacuum ultraviolet circular dichroism. 26 85

The ATP-dependent proteolytic cell-free system from reticulocytes has been resolved into three components, each of which is absolutely required for acid solubilization of 125I-labeled bovine serum albumin radioactivity. In addition to the previously reported heat-stable polypeptide [Ciechanover, A., Hod, Y. & Hershko, A. (1978) Biochem. Biophys. Res Commun. 81, 1100-1105], we now describe a protein of high molecular weight (approximately 450,000) that is labile at 42 degrees C. The extremely heat-labile factors is remarkably stabilized by ATP. GTP and CTP, which do not stimulate protolysis, do not stabilize this factor. Adenylate nucleotides such as ADP or the nonhydrolyzable beta,gamma imido or methylene analogues of ATP cause stabilization although they do not activate proteolysis. A third protein component of the protease system, stable at 42 degrees C, has been separated from the heat-labile species by salt precipitation. All three components are required with ATP for proteolytic activity, but thus far only the heat-labile factor has been shown to interact directly with ATP.
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PMID:Resolution of the ATP-dependent proteolytic system from reticulocytes: a component that interacts with ATP. 29 Sep 89

When cultured cells of the rat kangaroo cell line PtK2 grown on plastic or glass surfaces are lysed and extracted with combinations of low and high salt buffers and the non-ionic detergent Triton X-100 cytoskeletal preparations are obtained that show an enrichment of 6 to 11 nm thick filaments. The arrays of these filaments have been examined by various light and electron microscopic techniques, including ultrathin sectioning, whole mount transmission electron microscopy, negative staining, and indirect immunofluorescence microscopy. In addition, 6 to 11 nm filaments isolated from these cells with similar extraction procedures and with centrifugation techniques have been examined by electron microscopy. The arrays of these isolated intermediate-sized filaments, their ultrastructure and their specific decoration by certain antibodies present in normal rabbit sera as well as by guinea pig antibodies against purified bovine prekeratin is demonstrated. When preparations enriched in these intermediate-sized filaments are examined by SDS-polyacrylamide gel electrophoresis a corresponding enrichment of three polypeptide bands with apparent molecular weights of about 45 000, 52 000 and 58 000 (the latter component sometimes appears split into two bands) is observed, besides some residual actin and a few high molecular weight bands. The morphology of the isolated filaments, their immunological reaction with antibodies decorating prekeratin-containing structures, and the sizes of their constitutive polypeptides suggest that these filaments are closely related to prekeratin-containing filaments observed in a variety of epithelial cells.
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PMID:The intermediate-sized filaments in rat kangaroo PtK2 cells. II. Structure and composition of isolated filaments. 35 25

Collagens extracted from heart valves by using limited pepsin digestion were fractionated by differential salt precipitation. Collagen types were identified by sodium dodecyl sulphate/polyacrylamide-gel electrophoresis, amino acid analysis and cleavage with CNBr. Heart-valve collagen was heterogeneous in nature, consisting of a mixture of type-I and type-III collagens. The identity of type-III collagen was established on the basis of (a) insolubility in 1.7 M-NaC1 at neutral pH, (b) behaviour of this collagen fraction on gel electrophoresis under reducing and non-reducing conditions, (c) amino acid analysis showing a hydroxyproline/proline ratio greater than 1, and (d) profile of CNBr peptides on sodium dodecyl sulphate/polyacrylamide-gel electrophoresis showing a peak characteristic for type-III collagen containing peptides alpha1(III)CB8 and alpha1(III)CB3. In addition to types-I and -III collagen, a collagen polypeptide not previously described in heart valves was identified. This polypeptide represented approx. 30% of the collagen fraction precipitated at 4.0 M-NaCl, it migrated between beta- and alpha1-collagen chains on sodium dodecyl sulphate/polyacrylamide-gel electrophoresis and its electrophoretic behaviour was not affected by disulphide-bond reduction. All collagen fractions from the heart valves contained increased amounts of hydroxylysine when compared with type-I and -III collagens from other tissues. The presence of beta- and gamma-chains and higher aggregates in pepsin-solubilized collagen indicated that these collagens were highly cross-linked and suggested that some of these cross-links involved the triple-helical regions of the molecule. It is likely that the higher hydroxylysine content of heart-valve collagen is responsible for the high degree of intermolecular cross-linking and may be the result of an adaptive mechanism for the specialized function of these tissues.
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PMID:Characterization of pepsin-solubilized bovine heart-valve collagen. 36 Oct 35

A mixture of 30 S and 50 S subunits quantitatively absorbs on a column of Sepharose--4B from the buffer: 0.02 M Tris--HCl, pH 7.5, containing 1.5 M (NH4)2SO4. During elution by reverse gradient of ammonium sulphate (1.5--0.05 M) the subunits are eluted at different salt concentrations. Complete separation of subunits is attained in the absence of Mg2+ ions. The 30 S subunits prepared from 70 S ribosomes according to this procedure are fully active in the codon--dependent binding of a specific aminoacyl--tRNA. After their reassociation with 50 S subunits isolated by zonal centrifugation, the resulting 70 S ribosomes are active in polypeptide synthesis at the same degree as control 70 S ribosomes in which both types of subunits were prepared by zonal centrifugation. The initial 70 S ribosomes for the chromatographic separation into subunits can be obtained by their pelleting from a crude extract with subsequent washing with concentrated solutions of NH4Cl in the ultracentrifuge, or by salt fractionation of the crude extract according to a slightly modified procedure of Kurland.
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PMID:Separation of ribosomal subunits of Escherichia coli by Sepharose chromatography using reverse salt gradient. 36 25

Type AB2 collagen was isolated from normal lung parenchyma by pepsin extraction followed by differential salt extraction. This collagen comigrates with AB2 collagen isolated from placental membranes when run on 5% polyacrylamide gel electrophoresis; it has an alpha A and alpha B polypeptide chain ratio of 1 : 2 and a cyanogen bromide peptide profile similar to known AB2 collagen on 7.5% polyacrylamide gel electrophoresis. This AB2 collagen isolated from lung tissue specifically inhibits passive hemagglutination of affinity-purified rabbit antibodies to AB2 collagen isolated from amnionic and chorionic membranes. By indirect immunofluorescence microscopy, AB2 collagen was found to be widely distributed throughout the lung and was found preferentially associated with cell surfaces (basement lamina) and basement membranes.
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PMID:Isolation and tissue localization of type AB2 collagen from normal lung parenchyma. 37 11

Eukaryotic initiation factor 2 (eIF-2), which specifically binds Met-tRNAMetf and forms stable ternary complexes with GTP, has been purified from ribosomal salt wash proteins from calf liver. The purified factor exhibits only two polypeptide bands of Mr = 48,000 and 38,000 following electrophoresis in 15% polyacrylamide gels in the presence of sodium dodecyl sulfate. Densitometric tracings show the two polypeptides are present in a molar ratio of 1:1. This suggests a Mr = 86,000 for the native enzyme, a value which agrees with the apparent molecular weight determined by physical methods. Less pure preparations of eIF-2 show additional polypeptide bands, including 50,000- and 46,000-dalton bands, all of which can be removed by further purification without affecting the activity of eIF-2.
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PMID:Purified eukaryotic initiation factor 2 from calf liver consists of two polypeptide chains of 48,000 and 38,000 daltons. 45 54


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