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 major antifreeze polypeptide (AFP) from winter flounder (37 amino acid residues) is a single alpha-helix. Aspartic acid and arginine are found, respectively, at the amino and carboxyl-termini. These charged amino acids are ideally located for stabilizing the alpha-helical conformation of this AFP by means of charge-dipole interaction (Shoemaker, K. R., Kim, P.S., York, E.J., Stewart, J. M., and Baldwin, R. L. (1987) Nature 326, 563-567). In order to understand these and other molecular interactions that maintain the AFP structure, we have carried out the chemical synthesis of AFP analogs and evaluated their conformations by circular dichroism spectroscopy. We synthesized the entire AFP molecule (37-mer) and six COOH-terminal peptide fragments (36-, 33-, 27-, 26-, 16-, and 15-mers). Peptides containing acidic NH2-terminal residues displayed greater helix formation and thermal stability compared to those peptides of similar size, but with neutral NH2-terminal residues. Helix formation was maximum above pH 9.2. The peptide conformations also displayed a pH-dependent sensitivity to changes in ionic strength. Helix formation was reduced in the presence of acetonitrile. We conclude that the AFP helix is most likely stabilized by: charge-dipole interactions between charged terminal amino acids and the helix dipole, a charge interaction between Lys18 and Glu22 (either a salt bridge or a hydrogen bond), and hydrophobic interactions.
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PMID:Structure-function relationships in a winter flounder antifreeze polypeptide. I. Stabilization of an alpha-helical antifreeze polypeptide by charged-group and hydrophobic interactions. 273 67

Eubacterium sp. strain VPI 12708 is an anaerobic intestinal bacterium that has inducible bile acid 7-dehydroxylation activity. At least four new polypeptides were synthesized after addition of primary bile acids to the growth medium. One of these, of molecular weight 27,000 (P-27), was shown to be involved in the 7-dehydroxylation reaction sequence. The gene coding for P-27 was cloned, and the entire DNA sequence for the protein-coding region was determined. In addition, sequence information was obtained for 294 bases upstream from the translational start codon and 329 bases downstream from the stop codon. Induction studies with a synthetic oligonucleotide probe (16-mer) revealed the presence of a cholic acid-inducible mRNA species approximately 900 bases long. A 5' terminus of this mRNA was detected by primer extension analysis, and the location of the 3' terminus of the mRNA was estimated by using S1 nuclease mapping. The 3' terminus of the mRNA contained a large element with dyad symmetry of unknown function. The open reading frame contained 249 codons, and the corresponding polypeptide had a calculated molecular weight of 26,745. The amino acid sequence of P-27 showed significant homology to several previously described alcohol-polyol dehydrogenases ("nonzinc" dehydrogenases), especially in the region believed to contain a pyridine nucleotide-binding domain. The implications of this homology and the possible function of P-27 in bile acid 7-dehydroxylation are discussed.
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PMID:Nucleotide sequence and regulation of a gene involved in bile acid 7-dehydroxylation by Eubacterium sp. strain VPI 12708. 283 20

Translation arrest of genomic potato virus X (PVX) RNA promoted by complementary oligodeoxynucleotides in Krebs-2 cell-free system is described. 14-15 mer oligodeoxynucleotides complementary to the 5'-proximal cistron of PVX RNA were shown to induce specific truncation of the major non-structural polypeptide coded by PVX RNA. Evidence is presented that effective translational arrest of PVX RNA in the presence of complementary oligonucleotides results from the site-specific cleavage of RNA by endogenous RNase H intrinsic to the Krebs-2 extract. No similar translational arrest was found in the rabbit reticulocyte lysate cell-free system.
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PMID:Translation arrest of potato virus X RNA in Krebs-2 cell-free system: RNase H cleavage promoted by complementary oligodeoxynucleotides. 283 67

The Neurospora crassa copper metallothionein gene was cloned and its complete nucleotide sequence is reported. Enriched metallothionein mRNA was used as a template for cDNA synthesis, primed by a metallothionein-specific, synthetic undecanucleotide. The sequence of the cDNA obtained allowed the synthesis of a unique 21-mer which was used to screen a genomic DNA library of N. crassa. In agreement with the published amino acid sequence, the gene codes for a polypeptide 26 amino acid residues in length. The coding region is interrupted by a small intron (94 nucleotides). The gene structure is compared with those of mammalian metallothioneins. In both cases, the coding regions are split by introns, the intron-exon boundaries, however, are in different positions. The neurospora copper metallothionein gene is, to our knowledge, the smallest gene interrupted by an intron isolated so far.
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PMID:Isolation and structural organization of the Neurospora crassa copper metallothionein gene. 293 31

The Ca2+ binding sites of purified sarcoplasmic reticulum Ca2+-ATPase were filled with 0.1-20 microM Ca2+ to varying degrees of maximal Ca2+-binding capacity (1.9-2.3 mol/mol of the phosphorylatable enzyme) in the absence of ATP at pH 7.0 and 0 degree C. The exchange reaction of bound Ca2+ for unbound Ca2+ at equilibrium was studied by the nitrocellulose filtration method, and was compared with the dissociation reaction of the bound Ca2+ by EGTA. When about 90% of the Ca2+ sites were filled, half of the bound Ca2+ slowly exchanged at a rate about 20-30-times slower than the dissociation rate of about 0.3 s-1, i.e., the reaction was 'occluded'. The other half of the bound Ca2+ was not 'occluded', and rapidly exchanged at the same rate as the dissociation rate. The Ca2+ in both states was, however, equally dissociated by EGTA. The Ca2+ 'occlusion' was not as pronounced when 40-90% of the sites were filled. On the other hand, when less than 40% of the sites were filled, no Ca2+ 'occlusion' was observed, and the Ca2+ on the sites homogeneously exchanged. More than half of the unoccluded and exchangeable Ca2+ was converted to an 'occluded' state after saturation of the sites with Ca2+. Based on the fact that one Ca2+-ATPase polypeptide binds one Ca2+ (Verjovsky-Almeida, S. and Silva, J.L. (1981) J. Biol. Chem. 256, 2940-2944), these results suggest the existence of two types of interacting Ca2+-ATPase molecule which are kinetically distinguishable. It further suggests that the non-equivalence of the two sites, each of which is on one of the putative interacting molecules, is produced by Ca2+ saturation of the sites of the enzyme oligomer (2 X n-mer, n greater than 1) rather than by Ca2+ binding itself to the two putative sites. Ca2+ on one of the two sites may be 'occluded' in the enzyme. The Ca2+ 'occlusion' was relieved by ATP. The 'occluded' state seems to be involved in a process of the active Ca2+ transport in the sarcoplasmic reticulum.
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PMID:Calcium-dependent non-equivalent characteristics of calcium binding sites of the sarcoplasmic reticulum Ca2+-ATPase. 293 31

A synthetic 20-mer based on the known amino acid (aa) sequence of the N-terminus of Sendai virus F1 polypeptide was synthesized. Using this dI-probe, which contained deoxyinosines at all six ambiguous codon positions, we isolated clones carrying cDNAs for the F mRNA of Sendai virus. Nucleotide (nt) sequence analysis revealed a long open reading frame (ORF) that encodes a protein of 565 aa. Thus, this type of dI-probes should prove useful for selecting cDNA clones, when the aa sequence is known and is characterized by high codon redundancy.
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PMID:Use of the deoxyinosine-containing probe to isolate and sequence cDNA encoding the fusion (F) glycoprotein of Sendai virus (HVJ). 299 47

Overlapping deletion mutations were constructed in chimaeric plasmids carrying the mer operon of plasmid R100. Polypeptides specified by the mutant plasmids in Escherichia coli minicells correlated with the mer genes as follows: merT, 17- and 16-kDa polypeptides; merP, 9.8- and 9.5-kDa polypeptides; merC, a 14-kDa polypeptide; merA, 65- and 62-kDa polypeptides. The products of the merR and merD genes were not identified. The revised nomenclature of the mer genes is explained.
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PMID:Polypeptides specified by the mercuric resistance (mer) operon of plasmid R100. 301 42

The broad-spectrum mercurial-resistance plasmid pDU1358 was analyzed by cloning the resistance determinants and preparing a physical and genetic map of a 45-kilobase (kb) region of the plasmid that contains two separate mercurial-resistance operons that mapped about 20 kb apart. One encoded narrow-spectrum mercurial resistance to Hg2+ and a few organomercurials; the other specified broad-spectrum resistance to phenylmercury and additional organomercurials. Each determinant governed mercurial transport functions. Southern DNA X DNA hybridization experiments using gene-specific probes from the plasmid R100 mer operon indicated close homology with the R100 determinant. The 2153 base pairs of the promoter-distal part of the broad-spectrum Hg2+-resistance operon of pDU1358 were sequenced. This region included the 3'-terminal part of the merA gene, merD, unidentified reading frame URF1, and a part of URF2 homologous to previously sequenced determinants of plasmid R100. Between the merA and merD genes, an open reading frame encoding a 212 amino acid polypeptide was identified as the merB gene that determines the enzyme organomercurial lyase that cleaves the C--Hg bond of phenylmercury.
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PMID:Cloning and DNA sequence of the mercuric- and organomercurial-resistance determinants of plasmid pDU1358. 303 33

The mercurial-resistance determinant from Staphylococcus aureus plasmid pI258 is located on a 6.4-kilobase-pair Bgl II fragment. The determinant was cloned into both Bacillus subtilis and Escherichia coli. Mercury resistance was found only in B. subtilis. The 6404-base-pair DNA sequence of the Bgl II fragment was determined. The mer DNA sequence includes seven open reading frames, two of which have been identified by homology with the merA (mercuric reductase) and merB (organomercurial lyase) genes from the mercurial-resistance determinants of Gram-negative bacteria. Whereas 40% of the amino acid residues overall were identical between the pI258 merA polypeptide product and mercuric reductases from Gram-negative bacteria, the percentage identity in the active-site positions and those thought to be involved in NADPH and FAD contacts was above 90%. The 216 amino acid organomercurial lyase sequence was 39% identical with that from a Serratia plasmid, with higher conservation in the middle of the sequences and lower homologies at the amino and carboxyl termini. The remaining five open reading frames in the pI258 mer sequence have no significant homologies with the genes from previously sequenced Gram-negative mer operons.
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PMID:Nucleotide sequence and expression of the mercurial-resistance operon from Staphylococcus aureus plasmid pI258. 303 34

A cDNA clone encoding the entire transacylase (E2b) precursor of the bovine branched-chain alpha-keto acid dehydrogenase complex has been constructed from two overlapping incomplete cDNA clones which were isolated from a lambda ZAP library prepared from bovine liver poly(A)+ RNA. Nucleotide sequencing indicates that this bovine E2b cDNA insert (bE2-11) is 2701 base pairs in length with an open reading frame of 1446 base pairs. The bE2-11 cDNA insert encodes a leader peptide of 61 residues and a mature E2b polypeptide of 421 amino acid residues with a calculated monomeric molecular mass of 46,518 daltons. The molecular mass of the native E2b component isolated from bovine liver is 1,110,000 daltons as determined by sedimentation equilibrium. This value establishes the 24-subunit octahedral model for the quaternary structure of bovine E2b. The amino-terminal sequences of two tryptic fragments (A and B) of the E2b protein have been determined. Fragment A comprises residues 175 to 421 of the E2b protein and is the inner E2 core domain which contains the transacylase active site. Fragment B, produced by further tryptic cleavage of fragment, comprises residues 205 to 421, but does not have transacylase activity. Both fragments A and B confer the highly assembled 24-mer structure. The primary structure of the inner E2 core domain of bovine E2b (fragment A) is very similar to those of three other E2 proteins (human E2p, Escherichia coli E2p, and E. coli E2k). These similarities suggest that these E2 proteins are structurally and evolutionarily related.
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PMID:Characterization and conservation of the inner E2 core domain structure of branched-chain alpha-keto acid dehydrogenase complex from bovine liver. Construction of a cDNA encoding the entire transacylase (E2b) precursor. 304 70


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