Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0021400 (influenza)
 57,666 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The arginine carboxypeptidase involved in the proteolytic cleavage of the haemagglutinin of influenza A virus has been analysed by an assay employing a Sepharose-bound peptide containing radioactive arginine as a substrate. The enzyme activity has been extracted from purified virus with non-ionic detergents and has been separated from the haemagglutinin and from the neuraminidase by isoelectric focusing and by affinity chromatography. The carboxypeptidase present in virus grown in different host cells shows variations in its isoelectric point. It can be concluded from these observations that the carboxypeptidase is a host component incorporated into the virus envelope. When the enzyme is inhibited by 2-mercaptomethyl-3-guanidinoethyl-thiopropanoic acid, haemagglutinin with the arginine attached to the carboxy terminus of HA1 can be obtained. The observation that under these conditions the haemagglutinin has retained its haemolytic activity indicates that the carboxypeptidase does not play an essential role in the activation process.
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PMID:Characterization of the carboxypeptidase involved in the proteolytic cleavage of the influenza haemagglutinin. 661

The complete nucleotide sequence of the influenza C/California/78 virus RNA 4 was obtained by using cloned cDNA derived from the RNA segment. This gene is 2,071 nucleotides long and can code for a polypeptide of 654 amino acids. Although there are no convincing sequence homologies between RNA 4 and the hemagglutinin genes of influenza A and B viruses, we suggest, on the basis of structural features, that RNA 4 of the influenza C virus codes for the hemagglutinin. The structural features which are common to the hemagglutinins of influenza A, B, and C viruses include (i) a hydrophobic signal peptide, (ii) an arginine cleavage site between the hemagglutinin 1 and 2 subunits, (iii) hydrophobic regions at the amino and carboxyl termini of the hemagglutinin 2 subunit, and (iv) several conserved cysteine residues. Additional evidence that RNA 4 of influenza C virus codes for the hemagglutinin is that the tripeptide Ile-Phe-Gly, known to be present at the amino terminus of the hemagglutinin 2 subunit of influenza C virus, is encoded by RNA 4 at a point immediately adjacent to the presumptive arginine cleavage site. The lack of primary sequence homology between the influenza C virus hemagglutinin and the influenza A or B virus hemagglutinins, which all have similar functions, might be attributed to convergent rather than divergent evolution. However, the structural similarities among the influenza A, B, and C virus hemagglutinins strongly suggest that the three hemagglutinin genes have diverged from a common precursor.
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PMID:Influenza C virus hemagglutinin: comparison with influenza A and B virus hemagglutinins. 669 42

Some of the properties of the tetrapeptide tuftsin, Thr-Lys-Pro-Arg, are discussed. We describe three phases of tuftsin activation of the macrophage. Tuftsinyltuftsin, the octapeptide Thr-Lys-Pro-Arg-Thr-Lys-Pro-Arg, was synthesized with a view of minimizing the formation of Lys-Pro-Arg, from tuftsin by tissue aminopeptidases. The tripeptide is a tuftsin inhibitor. The octapeptide proved to be quite effective in prolonging the life of syngeneic mice injected with L1210 leukemia cells. Its effect in our laboratory, was considerably better than we could obtain with tuftsin. A simple method for purifying tuftsin by high performance liquid chromatography is described using 0.75% trifluoroacetic acid in water. The tuftsin sequence Thr-Lys-Pro-Arg is present in P12 protein of Rausher murine leukemia virus. A close analog Thr-Arg-Pro-Lys appears in yet another virus protein the haemagglutinin of influenza virus. A second close analog Thr-Arg-Pro-Arg forms the penultimate carboxyterminal of a pancreatic polypeptide found in human and several animals.
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PMID:Tuftsin, a natural activator of phagocytic functions including tumoricidal activity. 689 74

The complete nucleotide sequence of the hemagglutinin (HA) gene of a type B influenza virus (B/Lee/40) was obtained by using cloned cDNA derived from the RNA segment. The gene is 1,882 nucleotides long and can code for a protein precursor of 584 amino acids. Structural features common to type A virus HAs are also conserved in the B virus HA. These include a hydrophobic signal peptide, hydrophobic NH2 and COOH termini of the HA2 subunit, and a HA1/HA2 cleavage site involving an arginine residue. The sequence of the B HA gene and its deduced amino acid sequence were compared to those of a type A influenza virus (A/PR/8/34). When these two genes were aligned, it was found that 24% of the amino acids in the HA1 subunits and 39% of the amino acids in the HA2 subunits are conserved. This degree of relatedness between type B virus and type A virus HAs (intertypic comparison) is similar to the homologies observed among certain type A virus HAs (intratypic comparison). A close evolutionary relationship is therefore suggested between the HAs of type A and type B influenza viruses.
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PMID:Evolution of influenza A and B viruses: conservation of structural features in the hemagglutinin genes. 695 92

Recent studies of Reye syndrome (RS) patients have suggested aspirin treatment as a possible factor in the etiology of this often fatal childhood disorder. the relationship of aspirin treatment to other factors that have been strongly implicated (influenza, ammonia toxicity) cannot be examined directly in patients because aspirin treatment is usually initiated by family members in the prodromal period before RS is diagnosed. In this report we describe the use of an animal model for RS in examining the interactions of these several potential etiological factors. Hyperammonemia and coma were produced in young male ferrets by a brief feeding of an arginine-deficient diet. The effects of influenza infection or aspirin treatment (or both) of control and hyperammonemic ferrets on their serum levels of ammonia, glutamic-oxaloacetic transaminase (GOT;L-aspartate:2-oxoglutarate aminotransferase, EC 2.6.1.1), ornithine carbamoyltransferase (OCT; carbamoylphosphate:L-ornithine carbamoyltransferase, EC 2.1.3.3), bilirubin, and salicylate were studied. Liver levels of lipids, proteins, and several urea-cycle enzymes were also determined in the comatose ferrets and compared with those of untreated controls and of controls treated with influenza or aspirin, or both. Synergism of these three factors (hyperammonemia, influenza infection, and aspirin treatment) in causing RS-like alterations in these parameters was observed.
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PMID:Interactions of aspirin and other potential etiologic factors in an animal model of Reye syndrome. 696 32

When influenza A/RI/5+ virus-infected cells were incubated in medium to which 2 micrograms of canavanine (arginine analog) per ml had been added 4 hr after infection, all viral polypeptides were synthesized but the budding-like process with the appearance of extracellular virus was completely inhibited. The plasma membrane isolated from these cells contained exclusively hemagglutinin (HA), and membrane (M) protein and nucleoprotein (NP) appeared to be associated with the nucleus, in contrast to untreated cells whose plasma membrane contained abundant HA, M protein, and NP. Disruption of canavanine-treated cells by freeze-thawing generated a number of hemagglutinating membranous vesicles or fragments containing exclusively HA. By isotope labeling it was found that the M protein synthesized in the presence of canavanine, together with HA and NP, is a canavanine-substituted polypeptide. It is suggested that canavanine inhibits the formation of the mature envelope of influenza RI/5+, because of the inability of M protein to associate with the plasma membrane.
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PMID:Analysis of the inhibitory effect of canavanine on the replication of influenza RI/5+ virus. II. Interaction of M protein with the plasma membrane. 703 6

A DNA copy of influenza A/NT/60/68 viral RNA segment 2, corresponding to protein P1, has been cloned in the E.coli plasmid pBr322. The clone is 2341 nucleotides long and represents a full-length copy of the viral RNA. In the viral complementary (plus sense) strand there is an open reading frame that is 2271 nucleotides long. The predicted primary gene product is a basic 86,300 dalton protein with a net charge at neutral pH of +23. A 29 amino acid stretch of the protein (coded by nucleotide residues 583-669) is highly basic and contains 7 lysine and 8 arginine residues. Other smaller clusters of basic amino acids are also present in the protein.
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PMID:The complete sequence of RNA segment 2 of influenza A/NT/60/68 P1 protein. 704 Oct 90

Young male ferrets developed hyperammonemia and encephalopathy soon after eating a diet lacking arginine. Because of this characteristic and their known susceptibility to influenza infections, they were further tested as an animal model for Reye's syndrome (RS), a childhood disorder which sometimes develops following influenza and which is characterized in part by encephalopathy, hyperammonemia, and elevated serum transaminase levels. Either the deficiency or infection alone resulted in minor elevations of serum ornithine carbamyl transferase (S-OCT) activities and together resulted in substantial elevations. These and associated alterations are discussed in relationship to the metabolic disorders occurring in RS.
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PMID:Serum enzyme alterations in arginine-deficient, influenza-infected ferrets: a potential animal model of Reye's syndrome. 706 89

The nucleotide sequence of polymerase 1 (P1) gene of a human influenza virus (A/WSN/33) has been determined by using cDNA clones, except for the last 83 nucleotides, which were obtained by primer extension. The WSN P1 gene contains 2,341 nucleotides and codes for a protein of 757 amino acids (Mr = 86,500). P1 gene possesses a striking tandem repeat of 12 nucleotides (nucleotide position 2,188 to 2,199, 2,200 to 2,211) and a corresponding tandem repeat of tetrapeptide in the P1 protein. The deduced sequence of P1 protein is enriched in basic amino acids, particularly arginine. In addition, it also contains clusters of basic amino acids which may provide sites for the interaction with the template virion RNA capped primer as well as with other proteins involved in viral replication and transcription. A secondary structure prediction, using Chou and Fasman analyses (Annu. Rev. Biochem. 47:251-276, 1978), shows that the P1 protein possesses some unique features, viz., one "four-helical supersecondary structure" and four "polypeptide double helices" (antiparallel beta-pleated sheets) which are considered important in RNA binding.
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PMID:Sequence analysis of the polymerase 1 gene and the secondary structure prediction of polymerase 1 protein of human influenza virus A/WSN/33. 714 69

Distinct amino acid (aa) residue motifs for peptides binding to HLA-A1 and HLA-B8 were identified by sequence analyses of reversed-phase HPLC fractions containing endogenous peptides derived from these HLA molecules. Fifteen different primary sequences were determined for HLA-A1-associated peptides, 12 of which were nine aa in length. Common features among these peptide sequences were Tyr at the COOH-terminus, a negatively charged aa (usually Glu) at position 3 (P3), and Pro at P4. Twenty-seven different primary sequence assignments were made for HLA-B8-associated peptides, most of which were eight aa in length. Lys, and in a few cases Arg, predominated at P3 and P5; Leu and Pro predominated at P2, and Leu was the preferred COOH-terminal residue. Unlike all other human class I molecules whose peptide-binding properties have been studied, both HLA-A1 and HLA-B8 endogenous peptide sequences have a dominant anchor residue at P3, and these aa are opposite in charge to the aa at position 156 of the peptide-binding site. Synthetic peptides corresponding to endogenous peptide sequences bound to their respective HLA molecules in vitro, indicating that they derive from peptides bound to HLA and not from copurifying contaminants. Eight of the HLA-A1 and HLA-B8 endogenous peptide sequences matched intracellularly expressed proteins found in protein sequence data bases. The HLA-A1 peptide-binding motif was then used to identify potential antigenic peptides from influenza A viral proteins that bound to HLA-A1 in vitro.
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PMID:Endogenous peptides with distinct amino acid anchor residue motifs bind to HLA-A1 and HLA-B8. 750 28


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