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)

The gene sequence for cytochrome oxidase subunit I (COI) in the ciliate Tetrahymena mitochondrial DNA has been determined and shown to be coded by the same strand as codes the genes (in order) for 14S rRNA, tRNA(trp), tRNA(glu), 21S rRNA, tRNA(leu) and tRNA(met). The predicted protein has 698 amino acids, including an NH2-terminal 57 amino acid extension and a 108 amino acid insert originally found in Paramecium COI. These extension and insert segments are not highly hydrophobic but are relatively rich in lysine, arginine and serine. In analogy with the presequence of nuclear-encoded mitochondrial proteins, they might function as a transmembrane signal. The remaining polypeptide segments show a hydrophobicity characteristic of membrane spanning proteins. TCOI shows a 64% amino acid identity with Paramecium COI but less than a 38% amino acid conservation with human COI. The Tetrahymena mitochondrial code is analogous with the mammalian mitochondrial code; but differs from the Tetrahymena nuclear genetic code; TGA is exclusively translated as tryptophan; ATA is used as an initiation codon probably for methionine, and TAA as a stop codon; the arginine codons (CGN) are not used. The use of the leucine codon TTA in TCOI is contradictory to the codon recognition pattern previously obtained from the isolated tRNA(leu) isoacceptors recognizing only the CUN codons, but consistent with the tRNA(leu) (anticodon UAA) gene encoded in the genome. The reason for this inconsistency has not been resolved.
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PMID:The cytochrome oxidase subunit I gene of Tetrahymena: a 57 amino acid NH2-terminal extension and a 108 amino acid insert. 283 63

Using a mutagenesis cartridge (R. J. Kuhn, H. Tada, M. F. Ypma-Wong, J. J. Dunn, B. L. Semler, and E. Wimmer, Proc. Natl. Acad. Sci. USA 85:519-523, 1988), we have generated single and multiple amino acid replacement mutants, as well as a single amino acid insertion mutant in the genome-linked protein VPg of poliovirus. Moreover, we constructed three different 5-amino-acid insertion mutants that map close to the C terminus of 3A, a viral polypeptide whose coding sequence is adjacent to VPg. Transfection of HeLa cells with RNA synthesized in vitro was used to test the effect of the mutation on viral proliferation. Mutations were either lethal or nonlethal. A temperature-sensitive phenotype was not observed. The arginine at position 17 of VPg could not be exchanged with any other amino acid without loss of viability, whereas the lysine at position 20, an amino acid conserved among all known polioviruses, coxsackieviruses, and echoviruses, was replaceable with several neutral amino acids and even with glutamic acid. Replacement of poliovirus VPg with echovirus 9 VPg yielded viable virus with impaired growth properties. Our results suggest considerable flexibility in the amino acid sequence of a functional VPg. All insertions in polypeptide 3A proved to be lethal. In vitro translation of mutated viral RNAs gave patterns of proteolytic processing that in some cases was aberrant, even though the mutation was nonlethal.
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PMID:Mutational analysis of the genome-linked protein VPg of poliovirus. 284 32

Three F0 subunits and the F1 subunit beta of the ATP synthase from Neurospora crassa were labeled with the lipophilic photoactivatable reagent 3-(trifluoromethyl)-3-(m-[125I]iodophenyl)diazirine ([125I]TID). In the proteolipid subunit which was the most heavily labeled polypeptide labeling was confined to five residues at the NH2-terminus and five residues at the C-terminus of the protein. Labeling occurred at similar positions compared with the homologous protein (subunit c) in the ATP synthase from Escherichia coli, indicating a similar structure of the proteolipid subunits in their respective organisms. The inhibitors oligomycin and dicyclohexylcarbodiimide did not change the pattern of accessible surface residues in the proteolipid, suggesting that neither inhibitor induces gross conformational changes. However, in the presence of oligomycin, the extent of labeling in some residues was reduced. Apparently, these residues provide part of the binding site for the inhibitor. After reaction with dicyclohexylcarbodiimide an additional labeled amino acid was found at position 65 corresponding to the invariant carbodiimide-binding glutamic acid. These results and previous observations indicate that the carboxyl side chain of Glu-65 is located at the protein-lipid interphase. The idea is discussed that proton translocation occurs at the interphase between different types if F0 subunits. Dicyclohexylcarbodiimide or oligomycin might disturb this essential interaction between the F0 subunits.
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PMID:Labeling of individual amino acid residues in the membrane-embedded F0 part of the F1 F0 ATP synthase from Neurospora crassa. Influence of oligomycin and dicyclohexylcarbodiimide. 286 44

It has been established indirectly that the N-termini of the thermal polyamino acids are pyroglutamic acid. This was determined by trifluoroacetic acid hydrolysis of the lactam ring followed by Dansyl labelling. The polyamino acids contained Ala, Gly, Glu, Leu, Phe, and Pro. In the experiments described here, the presence of pyroglutamic acid at the N-terminus of a polyamino acid was determined directly by the use of pyrrolidone carboxylyl peptidase. The enzyme catalyzes the removal of pyroglutamyl residues at the N-terminus of polypeptide chains. The polyamino acids used in these studies contained glutamic acid, aspartic acid, alanine, glycine, isoleucine, proline and valine. Alkaline hydrolysis was also used to determine indirectly that the N-termini of these polyamino acids are pyroglutamic acid. Another interesting finding was that many of the amino acids in the polymerization mixture were found to occur penultimate to the N-terminal amino acid. This is interpreted to mean that the diffusible fraction contains many polyamino acids.
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PMID:Pyroglutamyl N-termini of thermal polyamino acids. 288 17

A new lectin has been isolated from the coral Gerardia savaglia by affinity chromatography, using locust gum as an absorbent, and D-mannose as eluant. Final purification was achieved by Bio-Gel P300 gel filtration. The agglutinin is a protein composed of two polypeptide chains with a Mr of 14800; the two subunits are not linked by disulfide bond(s). The isoelectric point is 4.8, the amino acid composition is rich in the acidic amino acids aspartic acid and glutamic acid. The absorption maximum for the protein was at 276 nm; with a molar absorption coefficient of 1.27 X 10(5) M-1 cm-1. The lectin precipitated erythrocytes from humans (A, B and O), sheep, rabbit and carp with a titer between 2(5) and 10(10); the affinity constant for lectin binding to sheep red blood cells was 2.8 X 10(8) M-1 and the number of binding sites, 3.2 X 10(5)/cell. Ca2+ ions are required for full activity; the pH optimum lies in the range between 6 and 11. Inhibition experiments revealed that the lectin is specific for D-mannose. The lectin is mitogenic only for those spleen lymphocytes from mice which had been activated by lipopolysaccharide. An interesting feature of this lectin is its ability to bind to glycoproteins present in nuclei from CV-1 monkey kidney cells. The fluorescein-isothiocyanate-labelled lectin reacted with six polypeptides in the nuclear envelope from rat liver (Mr 190,000, 115,000, 80,000, 62,000, 56,000 and 42,000) and with two polypeptides in the nuclear matrix or pore complex lamina fraction (Mr 190,000 and 62,000). The lectin inhibited the nuclear envelope mRNA translocation system in vitro. It is suggested that this effect is due to an interaction of the lectin with the nuclear glycoproteins gp190 and/or gp62.
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PMID:A D-mannose-specific lectin from Gerardia savaglia that inhibits nucleocytoplasmic transport of mRNA. 289 May 21

For the polypentapeptide of elastin, (L-Val-L-Pro-Gly-L-Val-Gly)n, and appropriate analogs when suitably cross-linked, it has been previously demonstrated that development of elastomeric force at fixed length and length changes at fixed load occur as the result of an inverse temperature transition, with the temperature of the transition being inversely dependent on the hydrophobicity of the polypeptide. This suggests that at fixed temperature a chemical means of reversibly changing the hydrophobicity could be used for mechanochemical coupling. Evidence for this mechanism of mechanochemical coupling is given here with a 4%-Glu-polypentapeptide, in which the valine in position 4 is replaced in 1 out of 5 pentamers by a glutamic acid residue. Before cross-linking, the temperature for aggregation of 4%-Glu-polypentapeptide is remarkably sensitive to pH, shifting from 25 degrees C at pH 2 to 70 degrees C at pH 7.4 in phosphate-buffered saline (PBS). At 37 degrees C, the cross-linked 4%-Glu-polypentapeptide matrix in PBS undergoes a pH-modulated contraction and relaxation with a change from pH 4.3 to 3.3 and back. The mean distance between carboxylates at pH 4.3 in the elastomeric matrix is greater than 40 A, twice the mean distance between negatively charged species in PBS. Accordingly, charge-charge repulsion is expected to make little or no contribution to the coupling. Mechanochemical coupling is demonstrated at fixed load by monitoring pH dependence of length and at constant length by monitoring pH dependence of force. To our knowledge, this is the first demonstration of mechanochemical coupling in a synthetic polypeptide and the first system to provide a test of the recent proposal that chemical modulation of an inverse temperature transition can be a mechanism for mechanochemical coupling. It is suggested that phosphorylation and dephosphorylation may modulate structure and forces in proteins by locally shifting the temperatures of inverse temperature transitions.
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PMID:Mechanochemical coupling in synthetic polypeptides by modulation of an inverse temperature transition. 289 20

The rat neu oncogene encodes a cell surface glycoprotein, p185, that possesses tyrosine kinase activity. The p185 polypeptide exhibits structural similarity to the epidermal growth factor receptor (EGFR) at both the deduced amino acid and nucleic acid level. However, the neu oncogene and the gene encoding the EGFR have been shown to reside on distinct chromosomes. Comparative analysis of the sequences of the normal neu cDNA and of the neu cDNA from neuroblastomas has revealed a single point mutation leading to a valine-to-glutamic acid substitution in the transmembrane anchoring domain. This mutation converts the neu gene to a transforming gene in rodents. In humans, the gene is called ERBB2 (also NGL and HER2), and amplification and over-expression of its products have been detected in certain tumors. The rat embryonal fibroblast cell line (Rat-1) appears to express both EGFR and cellular p185 polypeptides. We have found that EGF stimulates the phosphorylation of p185 in these cells at tyrosine as well as serine and threonine residues in a specific and dose-dependent manner. This activity occurs even though radiolabeled EGF cannot bind to immunopurified p185. The EGF effect is apparently unique since platelet-derived growth factor, insulin, and transforming growth factor beta all fail to phosphorylate p185 at tyrosine. The EGF-induced effect requires interaction of the EGFR and its cognate ligand because cell lines that lack EGFR cannot be shown to phosphorylate p185, even when exposed to large amounts of EGF. Oncogenic rodent p185 and the human p185 homologue ERBB2 that is overexpressed in human breast tumor cells also can be shown to become phosphorylated on tyrosine residues by the action of EGF. Collectively, these data demonstrate that EGF mediates phosphorylation of p185 at tyrosine as well as serine/threonine through cellular kinases by a receptor-specific mechanism.
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PMID:Phosphorylation process induced by epidermal growth factor alters the oncogenic and cellular neu (NGL) gene products. 289 89

A cDNA that encodes what appears to be the inhibitory domain of the plasma membrane calcium-pumping ATPase (Ca2+-ATPase) has been isolated by screening a lambda gt11 bovine brain cDNA library with antibodies prepared against the human erythrocyte membrane Ca2+-ATPase. This screening resulted in isolation of a bacteriophage containing a 1.5-kilobase cDNA insert encoding a 71-residue polypeptide, the remainder being a large 3' terminal noncoding region. A portion of this deduced peptide sequence was identical to that of a peptide isolated from a V8 protease digest of the human erythrocyte Ca2+-ATPase except for 1 residue. Antibodies purified by immunoabsorption to the fusion protein containing this cDNA-encoded polypeptide reacted only with those fragments of a limited trypsin digest of the human erythrocyte Ca2+-ATPase that contain the inhibitory domain. Moreover, these antibodies were able to partially stimulate basal enzyme activity and block further activation by calmodulin. The encoded polypeptide bears homology to the glutamic acid-rich regions N-terminal to the Ca2+-binding loops of calmodulin and to a lesser extent with the loops themselves. This encoded polypeptide also represents the C terminus of the Ca2+-ATPase. Portions of the isolated cDNA were homologous to the 3' noncoding region of the sarcoplasmic reticulum Ca2+-ATPase cDNA, indicating a possible mechanism for the evolution of these distinct membrane Ca2+ pumps.
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PMID:A C-terminal, calmodulin-like regulatory domain from the plasma membrane Ca2+-pumping ATPase. 296 97

The complete primary structure of the cytoplasmically synthesized polypeptide VIc from beef heart cytochrome c oxidase was determined via isolation and sequencing of overlapping methionine and glutamic acid fragments. The protein consists of 73 amino acids (Mr 8 480). Through the protein contains, from residues 21 to 40, a hydrophobic sequence interrupted by one lysine it may not penetrate the membrane. A sequence of 33 amino acids highly homologous to the C-terminal part of VIc has been translated from a cDNA clone of a nuclear coded subunit of the enzyme from rat liver. The function of this component of the terminal oxidase is yet unknown.
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PMID:Studies on cytochrome c oxidase, XI. The amino-acid sequence of bovine heart polypeptide VIc. 298 83

The structural gene for the delta 5-3-ketosteroid isomerase of Pseudomonas testosteroni has been sequenced by the dideoxy method. The sequence obtained confirms the amino acid (aa) sequence of Benson et al. [J. Biol. Chem. 246 (1971) 7514-7525] at all but 5 aa residues of the 125-aa polypeptide. Amino acid residues 22, 24, 33, and 38, reported to be asparagines by Benson et al., are found to be encoded by aspartic acid codons. Amino acid residue 77, reported to be a glutamine by Benson et al., is encoded by a glutamic acid codon. The identification of aa 38 as aspartic acid, coupled with its presence in the active site, as indicated by previous affinity and photoaffinity-labeling studies and confirmed independently by x-ray crystallographic studies, strengthens the hypothesis that Asp-38 is the aa responsible for the 4 beta to 6 beta proton transfer which is part of the enzymatic reaction.
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PMID:Nucleotide sequence of the gene for the delta 5-3-ketosteroid isomerase of Pseudomonas testosteroni. 322 18


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