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 plaque size and hemagglutination characteristics of five cloned wild-type strains of polyomavirus were determined. The strains fell into two groups, those with large or small plaques, each with distinctive hemagglutination behavior at different temperatures and pHs. The nucleotide sequence of VP1, the major capsid protein of the virus, was determined for each of the viral strains. The PTA (large-plaque) and RA (small-plaque) strains differed only at residue 92 of VP1, where there is a glutamic acid or glycine, respectively (R. Freund, A. Calderone, C. J. Dawe, and T. L. Benjamin, J. Virol. 65:335-341, 1991). The same amino acid difference in VP1 correlated with plaque size and hemagglutination properties of the other sequenced viruses. Mutagenesis converting amino acid 92 from glutamic acid to glycine converted the plaque size and hemagglutination behavior of the large-plaque PTA strain to that of a small-plaque strain. Furthermore, PTA and RA VP1 proteins produced in Escherichia coli behaved as their parental viruses did in hemagglutination assays. These results demonstrate that amino acid residue 92 of VP1 is involved in determining the plaque size and hemagglutination behavior of polyomavirus and strongly suggest that this region of the VP1 polypeptide interacts directly with cell receptors.
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PMID:A single-amino-acid substitution in polyomavirus VP1 correlates with plaque size and hemagglutination behavior. 184 96

The Rhodospirillum rubrum structural gene puh, coding for the photoreaction center H polypeptide, and three other putative genes that surround puh were cloned and sequenced. The deduced 257 amino acid H polypeptide has a molecular weight of 27,909, in close agreement with polyacrylamide gel electrophoresis determination. Hydropathy plots predict a single hydrophobic alpha helix. The H polypeptide of Rhodospirillum rubrum shares only 23% of its residues with all three of the H polypeptides from Rhodopseudomonas viridis, Rhodobacter capsulatus, and Rhodobacter sphaeroides. Despite this apparent low degree of similarity, statistical analysis leaves no doubt about their close relatedness. Interspecies evolutionary distance, assessed by this analysis, confirms the closeness of the two Rhodobacter species, Rhodospirillum rubrum and Rhodopseudomonas viridis being approximately equidistant from them. Three regions of the H polypeptide are highly conserved in all four species. They correspond to known contact points of H with the complex of the other two (L and M) subunits on the cytoplasmic side of the membrane. A glutamic acid residue (H polypeptide residue 177), conserved in the other bacteria and suggested to be involved in the binding of secondary quinone QB, is replaced by serine in Rhodospirillum rubrum. The open reading frames G115, I2372, and I3087 are predicted to, respectively, encode polypeptides of 480, 224, and 155 residues coiled in 10, 2, and 1 transmembrane helices. Open reading frame G115 shares 56% identical residues with F1696, a sequence arranged in the genome of Rhodobacter capsulatus. The gene product of ORF I3087 is predicted to share highly similar sequences with nitrogenase reductase (encoded by nifH) of 11 different bacterial species and is suggested to have a regulatory function.
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PMID:The puh structural gene coding for the H subunit of the Rhodospirillum rubrum photoreaction center. 190 63

The nucleotide sequence of nirA, mediating nitrate induction in Aspergillus nidulans, has been determined. Alignment of the cDNA and the genomic DNA sequence indicates that the gene contains four introns and encodes a protein of 892 amino acids. The deduced NIRA protein displays all characteristics of a transcriptional activator. A putative double-stranded DNA-binding domain in the amino-terminal part comprises six cysteine residues, characteristic for the GAL4 family of zinc finger proteins. An amino-terminal highly acidic region and two proline-rich regions are also present. The nucleotide sequences of two mutations were determined after they were mapped by transformation with overlapping DNA fragments, amplified by the polymerase chain reaction. nirA87, a mutation conferring noninducibility by nitrate and nitrite, has a -1 frameshift at triplet 340, which eliminates 549 C-terminal amino acids from the polypeptide. Under the assumption that the truncated polypeptide is stable, it comprises the zinc finger domain and the acidic region, which seem not sufficient for transcriptional activation. nirAd-106, an allele conferring nitrogen metabolite derepression of nitrate and nitrite reductase activity, includes two transitions, changing a glutamic acid to a lysine and a valine to an alanine, situated between a basic and a proline-rich region of the protein. Northern (RNA) analysis of the wild type and of constitutive (nirAc) and derepressed (nirAd) mutants show that the nirA transcript does not vary between these strains, being in all cases constitutively expressed. On the other hand, transcript levels of structural genes (niaD and niiA) do vary, being highly inducible in the wild type but constitutively expressed in the nirAc mutant. The nirAd mutant appears phenotypically derepressed, because the niaD and niiA transcript levels are overinduced in the presence of nitrate but are still partially repressed in the presence of ammonium.
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PMID:nirA, the pathway-specific regulatory gene of nitrate assimilation in Aspergillus nidulans, encodes a putative GAL4-type zinc finger protein and contains four introns in highly conserved regions. 192 75

A third elderberry (Sambucus nigra L.) lectin (SNA-III) has been isolated from dry seeds by affinity chromatography on immobilized 2-acetamido-2-deoxy-D-galactose. This lectin is a blood-group, nonspecific glycoprotein containing 21% of carbohydrate, and is rich in asparagine (or aspartic acid), serine, glutamine (or glutamic acid), and glycine. Gel filtration on Superose 12 yielded a single symmetrical peak corresponding to mol. wt. 50,000, SDS-poly(acrylamide) gel (SDS-PAGE) electrophoresis showed a single polypeptide band of 33 kDa, indicating that the native protein is a dimer of identical subunits. Hapten-inhibition assays of the agglutination of red blood cells showed that 2-acetamido-2-deoxy-D-galactose is the best inhibitor, being twice as potent as D-galactose, melibiose, and 2-amino-2-deoxy-D-galactose. A comparison of SNA-III to the previously described elderberry-bark lectins, SNA-I and SNA-II, indicated that the seed lectin is well distinct from them.
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PMID:Isolation and characterization of a seed lectin from elderberry (Sambucus nigra L.) and its relationship to the bark lectins. 193 55

The role of the penultimate and conserved tyrosine residue of the K99 major fibrillar subunit (FanC) in fibrillae biosynthesis and functioning was investigated. By using oligonucleotide-directed in vitro mutagenesis the TAT codon of tyrosine-158 of fanC was changed into a TAG stop codon. The mutant fanC gene encoded a truncated major subunit lacking the two carboxyl-terminal amino acid residues. Furthermore, the tyrosine residue (position 158) was replaced by a serine residue or by a glutamic acid residue. The effect of these mutations on the expression and binding capacity of K99 fibrillae was investigated by using an ELISA, an haemagglutination assay, Escherichia coli minicells and suppressor strains. All mutations completely blocked K99 fibrillae biosynthesis and haemagglutination activity. The mature form of the truncated mutant FanC polypeptide could not be detected in minicells, but its precursor was expressed at a normal level. The results showed that the penultimate tyrosine residue is essential for the expression of mature fibrillar subunits and suggested a function in the interaction with the periplasmic transport protein FanE.
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PMID:The penultimate tyrosine residue of the K99 fibrillar subunit is essential for stability of the protein and its interaction with the periplasmic carrier protein. 197 Mar 18

Murine interleukin-6 (mIL-6) was expressed in Escherichia coli in the insoluble fraction of cell lysates. Approximately equal amounts of two polypeptide species, reactive with anti-IL-6 antibodies, were produced. The two forms of mIL-6 were isolated and found to have identical N-terminal sequences initiated by Met-Phe-Pro-Thr-Ser-Gln-. Peptide mapping after endoproteinase glu-C digestion led to isolation and characterization of the C-terminal peptides from each of the two forms and allowed the source of the heterogeneity to be identified as a C-terminal addition of three amino acids, Gln-Lys-Leu, to authentic mIL-6. Inspection of the nucleotide sequence of the plasmid containing the mIL-6 gene and expression of the plasmid in other strains suggested that the addition of three amino acids was caused by a readthrough of the termination codon arising from an unexpected suppressor mutation in the original host strain. Although the C-terminus of IL-6 is critical for the activity of this cytokine, the IL-6 variant with extended C-terminus was fully active in two separate bioassays. This suggests that the additional amino acids do not disrupt the structure or function of this important region of the molecule.
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PMID:Identification and characterization of a C-terminally extended form of recombinant murine IL-6. 203 66

Several years ago, we proposed that polypeptide regions rich in proline (P), glutamic acid (E), serine (S), and threonine (T) (PEST) target intracellular proteins for destruction (Rogers, S., Wells, R., and Rechsteiner, M. (1986) Science 234, 364-368). To test the PEST hypothesis, we have produced chimeric proteins in which the N or C terminus of mouse dihydrofolate reductase is extended by the PEST-containing C terminus of mouse ornithine decarboxylase. Oligonucleotides encoding the 37 C-terminal residues of mouse ornithine decarboxylase (mODC) or equivalent lengths of dissimilar amino acids were inserted at appropriate sites in a dihydrofolate reductase (DHFR) expression vector. The various fusion proteins were expressed in Escherichia coli and purified to homogeneity by enzyme affinity chromatography. All purified fusion proteins exhibited similar abilities to convert dihydrofolate to tetrahydrofolate, thereby demonstrating that the attachment of peptide extensions to either terminus did not prevent the proper folding of DHFR. Metabolic stabilities of the radioiodinated fusion proteins were assayed in rabbit reticulocyte lysate or Xenopus egg extract. Proteolysis was found to be energy-dependent with mODC-DHFR fusion proteins being degraded from 2 to almost 40-fold faster than the parental DHFR molecule or DHFR fusion proteins bearing non-PEST extensions. Deletion of most of the PEST region from the mODC extension resulted in a significantly more stable fusion protein. Rapid proteolysis of DHFR proteins containing intact mODC extensions provides support for the PEST hypothesis.
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PMID:The C terminus of mouse ornithine decarboxylase confers rapid degradation on dihydrofolate reductase. Support for the pest hypothesis. 204 Jun 28

Squalene synthetase (farnesyl-diphosphate: farnesyl-diphosphate farnesyltransferase, EC 2.5.1.21) is a critical branch point enzyme of isoprenoid biosynthesis that is thought to regulate the flux of isoprene intermediates through the sterol pathway. The structural gene for this enzyme was cloned from the yeast Saccharomyces cerevisiae by functional complementation of a squalene synthetase-deficient erg9 mutant. Identification of this ERG9 clone was confirmed by genetic linkage analysis in yeast and expression of enzyme activity in Escherichia coli. The predicted squalene synthetase polypeptide of 444 amino acids (Mr, 51,753) lacks significant homology to known protein sequences, except within a region that may represent a prenyl diphosphate (substrate) binding site. The ERG9-encoded protein contains a PEST consensus motif (rich in proline, glutamic acid, serine, and threonine) present in many proteins with short cellular half-lives. Modeling of the protein suggests that it contains at least one, and possibly two, membrane-spanning domains. Disruption of the chromosomal squalene synthetase coding region by insertional mutagenesis indicates that ERG9 is a single copy gene that is essential for cell growth in yeast.
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PMID:Molecular cloning and characterization of the yeast gene for squalene synthetase. 206 81

Gene 22 of bacteriophage T4 encodes a major prohead scaffolding core protein of 269 amino acid residues. From its nucleotide sequence the gene product (gp) 22 has a predicted Mr of 29.9 and a pI of 4.3. The protein is rich in charged residues (glutamic acid and lysine) and contains low amounts of proline and glycine and no cysteine residues. We suggest that gp22 undergoes limited proteolytic processing which eliminates the short C-terminal piece from the molecule during the early steps of prohead assembly. Most amino acid residues of the gp22 polypeptide chain (80%) have an alpha-helical conformation and form seven peculiar alpha-helices. A model suggesting the spatial organization of gp22 is presented. Three long alpha-helices numbered 1 (1A and 1B), 3, and 5 (5A and 5B) are packed in an antiparallel fashion along the major axis of the road-shaped molecule. Two rather short alpha-helices (2 and 4) are located at the distal and proximal ends of the protein molecule, respectively. Helix number 2, which is a proteolytic fragment of gp22 found in mature T4 heads, is packed with helices 1A and 3, similar to a novel element of supersecondary structure, the alpha alpha-corner. Helix number 4 probably interacts with the gp20 connector of the prohead. The implications of the structure of the gp22 molecule for the assembly of the prohead core are discussed.
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PMID:A proposed structure of bacteriophage T4 gene product 22--a major prohead scaffolding core protein. 208 48

Glutactin, a new acidic sulfated glycoprotein, was isolated from Drosophila Kc cell culture media. Immunofluorescence microscopy located it to embryonic basement membranes, particularly to the sequentially invaginated envelope of the central nervous system, muscle apodemes and dorsal median cell processes. Its chromosome locus is 29D. The nucleic acid sequence coding for the 1023 residue long polypeptide contains one intron and was confirmed by partial amino acid sequencing. Glutactin has a signal peptide and an amino domain of greater than 500 residues that strongly resembles acetylcholine esterases and other serine esterases, but lacks the catalytically critical serine residue. The amino and carboxyl domains of glutactin are separated by 13 contiguous threonine residues. Glutamine and glutamic acid make up 44% of glutactin's very acidic carboxyl domain. Glutactin preferentially binds Ca2+ in the presence of excess Mg2+ and four of its tyrosines are O-sulfated. Several similarities with mammalian entactin caused our previous, preliminary mention of glutactin as a putative Drosophila entactin, but sequence comparison now shows them to be different proteins.
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PMID:Glutactin, a novel Drosophila basement membrane-related glycoprotein with sequence similarity to serine esterases. 210 64


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