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1.
Glycoconj J ; 13(5): 709-16, 1996 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-8909997

RESUMO

Mucin glycoproteins are a major constituent of salivary secretions and play a primary role in the protection of the oral cavity. Rat submandibular glands (RSMG) synthesize and secrete a low molecular weight (114 kDa) mucin glycoprotein. We have isolated, partially sequenced, and characterized the gene which encodes the RSMG apomucin. The gene is encoded by three exons of 106 nt, 69 nt, and 991 nt, separated by introns of 921 nt and 12.5 kb. CAAT and TATA elements are present, at -68 and -26, respectively, in the 5' flanking sequence of the RSMG apomucin gene. The tandem repeat domain present in exon III consists of ten tandem repeats of 39 nt encoding the consensus sequence PTTDSTTPAPTTK. Sequence comparison and organization of the nucleic acid sequence encoding the tandem repeats of two alleles for this gene suggests that the apomucin gene has undergone recombinational events during its evolution. No significant sequence similarity was found with other mucin genes, or with other known salivary gland-specific genes. The gene was localized to rat chromosome 14 using somatic cell hybrids that segregate rat chromosomes. Since this, to our knowledge, represents the first RSMG mucin gene cloned, we have designated this gene Mucsmg.


Assuntos
Mucinas Gástricas/química , Glândula Submandibular/química , Sequência de Aminoácidos , Animais , Bacteriófago lambda/genética , Sequência de Bases , Mapeamento Cromossômico , Clonagem Molecular , Primers do DNA , DNA Complementar/química , Biblioteca Gênica , Dados de Sequência Molecular , Ratos , Sequências Repetitivas de Ácido Nucleico , Alinhamento de Sequência , Análise de Sequência
2.
Biochim Biophys Acta ; 1219(2): 380-8, 1994 Oct 18.
Artigo em Inglês | MEDLINE | ID: mdl-7522572

RESUMO

It has been proposed that Asp-443, Glu-478, and Asp-498 are important in RNase H mediated catalysis by human immunodeficiency virus-1 reverse transcriptase (Davies J.F., Hostomska, Z. Hostomsky, Z., Jordan, S.R. and Matthews, D.A. (1991) Science 251, 88-95; Mizrahi, V., Usdin, M.T., Harington, A. and Dudding, L.R. (1990) Nucleic Acids Res. 18, 5359-5363). Single point mutations at either position 443 (Mizrahi, V., Usdin, M.T., Harington, A. and Dudding, L.R. (1990) Nucleic Acids Res. 18, 5359-5363) or 478 (Schatz, O., Cromme, F.V., Grüninger-Leitch, F. and Le Grice, S.F.J. (1989) FEBS Lett. 257, 311-314) severely inhibit RNase H activity but have only small effects on polymerase activity. We show here that a single mutation at position 498 of Asp to Asn (mutant D498N) results in a stable enzyme with a 20-fold reduction in the ratio of RNase H to polymerase activity. The mutant and wild type enzymes were equally processive, paused in the same locations, and extended primers at the same rate during DNA synthesis on a heteropolymeric RNA template. The rate of elongation on the homopolymeric template poly(rA) was also the same. The results indicate that the mutation does not affect normally measured catalytic parameters of the polymerase function of the enzyme. D498N catalyzed strand transfer synthesis on homopolymeric, but not heteropolymeric templates, indicating that RNase H activity is not required for the former activity, but is for the latter.


Assuntos
HIV-1/enzimologia , DNA Polimerase Dirigida por RNA/química , Ribonuclease H/metabolismo , Asparagina/química , Ácido Aspártico/química , Sequência de Bases , DNA Polimerase Dirigida por DNA/química , Transcriptase Reversa do HIV , Dados de Sequência Molecular , DNA Polimerase Dirigida por RNA/metabolismo , Especificidade por Substrato , Moldes Genéticos
3.
J Biol Chem ; 269(24): 16845-52, 1994 Jun 17.
Artigo em Inglês | MEDLINE | ID: mdl-8207007

RESUMO

Overlapping cDNA clones which encode the protein core of a rat submandibular gland mucin-glycoprotein have been isolated and characterized. Sequence analysis revealed a translated region of 966 nucleotides encoding a protein of 322 amino acid residues. The translational start site begins with a putative signal sequence comprising the initial 22 N-terminal residues. The predicted secreted portion of the apomucin revealed three distinct domains: an N-terminal domain which is enriched in glutamine (14%), proline (13%), and tyrosine (10%); a central region which consisted of eleven, 39-base pair tandem repeats with the consensus sequence PTTDSTTPAPTTK; and a C-terminal domain which is enriched in threonine and serine residues (47%) which are not part of a repeat motif. The expression of apomucin transcript appears restricted to the rat submandibular and sublingual glands. Southern blot analysis of rat genomic DNAs suggested a low copy number (1, 2) for this apomucin gene and a limited polymorphism in the number of tandem repeats. Collectively, our sequence and expression data indicate that the cloned rat submandibular gland apomucin is distinct from any of the other salivary (bovine, porcine, or human) or rat apomucins reported thus far.


Assuntos
Mucinas Gástricas , Biossíntese Peptídica , Glândula Submandibular/metabolismo , Sistema ABO de Grupos Sanguíneos , Sequência de Aminoácidos , Animais , Sequência de Bases , Southern Blotting , Clonagem Molecular , Sequência Consenso , DNA/análise , DNA/metabolismo , DNA Complementar/isolamento & purificação , DNA Complementar/metabolismo , Biblioteca Gênica , Dados de Sequência Molecular , Fragmentos de Peptídeos/química , Fragmentos de Peptídeos/isolamento & purificação , Peptídeos/genética , Peptídeos/isolamento & purificação , Reação em Cadeia da Polimerase , Conformação Proteica , Ratos , Mapeamento por Restrição
4.
J Lipid Res ; 18(4): 474-9, 1977 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-894139

RESUMO

Lion anal sac secretion were found to be richer in lipids and to contain more complex less uniform mixtures of lower moleculas weight lipids then the anal sac of the red fox. In the lion, homologous series of 1-alkylglycerols and 2-hydroxy-fatty acids were identified. Phenylacetic, 3-phenylpropionic, and related hydroxylated acids were also observed. Gas-liquid chromatography profiles of fox anal sac secretion lower molecular weight lipids were found to be less variable in their major constituents and to be dominated by relatively few large peaks, mainly (derivatized) fatty acids. Indole was also identified. Free cholesterol, and occasionally, stanols were observed in fox and lion secretions. In the red fox, total cholesterol levels averaged 0.93 mg/g (% free, 56.4), n = 5. Findings are discussed in relation to histological and anatomical similarities and differences between the anal sacs of the lion and the fox and in the context of the role of these secretions in chemical communication.


Assuntos
Sacos Anais/metabolismo , Carnívoros/metabolismo , Raposas/metabolismo , Leões/metabolismo , Metabolismo dos Lipídeos , Animais , Colesterol/metabolismo , Cromatografia Gasosa , Cromatografia em Camada Fina , Ácidos Graxos/análise , Hidroxiácidos/análise , Masculino , Peso Molecular , Especificidade da Espécie
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