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The genes encoding the envelope glycoprotein H (gH) and gB homologues were identified by sequencing genomic clones of human herpesvirus-7 (HHV-7), strain JI. A gB cDNA clone from HHV-7 strain AL was also identified. The deduced primary translation products of the gH and gB genes are a protein of 690 amino acids, with a predicted mass of 80.4 kD, and a protein of 822 amino acids, with a predicted mass of 93.3 kD, respectively. Both the predicted proteins have the characteristics of transmembrane glycoproteins, containing signal and transmembrane sequence motifs and characterized by the presence of 10 (gH) and 11 (gB) potential motifs for N-glycosylation. Comparison of amino acid sequence of HHV-7 gH and gB with the homologous sequences of the other human herpesviruses reveals closest homology with HHV-6 (38.8% identity for gH, 56.2% identity for the gB). In addition, significant sequence similarity was also observed between the gH and gB of HHV-7 and the homologs encoded by human cytomegalovirus (21.6% identity for gH, 37.6% identity for gB). No significant differences existed between the gB sequence of the two different HHV-7 strains analyzed. The products of the HHV-7 gH and gB expressed transiently in eukaryotic cells were specifically recognized by an HHV-7-reactive human serum in immunofluorescence assays.  相似文献   

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The gene responsible for the second form of autosomal dominant polycystic kidney disease, PKD2, has recently been identified. We now describe the cloning, genomic localization, cDNA sequence, and expression analysis of its murine homologue, Pkd2. The cloned cDNA sequence is 5134 bp long and is predicted to encode a 966-amino-acid integral membrane protein with six membrane-spanning domains and intracellular NH2 and COOH termini. Pkd2 is highly conserved with 91% identity and 98% similarity to polycystin-2 at the amino acid level. Pkd2 mRNA is widely expressed in mouse tissues. Pkd2 maps to mouse Chromosome 5 and is excluded as a candidate gene for previously mapped mouse mutations resulting in a polycystic kidney phenotype.  相似文献   

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The egg jelly coats of sea urchins contain sulfated fucans which bind to a sperm surface receptor glycoprotein to initiate the signal transduction events resulting in the sperm acrosome reaction. The acrosome reaction is an ion channel regulated exocytosis which is an obligatory event for sperm binding to, and fusion with, the egg. Approximately 90% of individual females of the sea urchin Strongylocentrotus purpuratus spawned eggs having only one of two possible sulfated fucan electrophoretic isotypes, a slow migrating (sulfated fucan I), or a fast migrating (sulfated fucan II) isotype. The remaining 10% of females spawned eggs having both sulfated fucan isotypes. The two sulfated fucan isotypes were purified from egg jelly coats and their structures determined by NMR spectroscopy and methylation analysis. Both sulfated fucans are linear polysaccharides composed of 1-->3-linked alpha-L-fucopyranosyl units. Sulfated fucan I is entirely sulfated at the O -2 position but with a heterogeneous sulfation pattern at O -4 position. Sulfated fucan II is composed of a regular repeating sequence of 3 residues, as follows: [3-alpha-L-Fuc p -2,4(OSO3)-1-->3-alpha-L-Fuc p -4(OSO3)-1-->3-alpha-L-Fuc p -4(OSO3)-1]n. Both purified sulfated fucans have approximately equal potency in inducing the sperm acrosome reaction. The significance of two structurally different sulfated fucans in the egg jelly coat of this species could relate to the finding that the sperm receptor protein which binds sulfated fucan contains two carbohydrate recognition modules of the C-type lectin variety which differ by 50% in their primary structure.  相似文献   

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Fertilin (previously known as PH-30) is a sperm protein that is a candidate molecule for mediating the binding and fusion of the sperm and egg plasma membranes. Fertilin is a heterodimer, with a beta subunit that has a region of homology to the disintegrin family of integrin ligands and an alpha subunit that has a region of homology to viral fusion peptides. It has been hypothesized that fertilin beta and alpha subunits mediate the interactions between sperm and egg plasma membranes, namely, binding and fusion, respectively. To address this hypothesis and to examine specifically the role of fertilin alpha in fertilization, we have expressed the predicted extracellular domain of mouse fertilin alpha as a bacterial fusion protein with maltose-binding protein. This fusion protein (hereafter referred to as recombinant fertilin alpha-EC) binds to the microvillar region of zona pellucida (ZP)-free eggs, the region of the membrane to which sperm bind. This binding is reduced in the absence of divalent cations and is supported by Ca2+, Mg2+, or Mn2+. Eggs that have been treated with chymotrypsin bind less recombinant fertilin alpha-EC than do untreated eggs, suggesting that a chymotrypsin-sensitive binding site for recombinant fertilin alpha-EC is present on egg surfaces. Binding to eggs is also affected by the method used to remove the ZP. Finally, recombinant fertilin alpha-EC inhibits the binding of sperm to eggs during in vitro fertilization of ZP-free eggs. These data are the first evidence to suggest that fertilin alpha can function as a cell adhesion molecule during fertilization, mediating the binding of sperm and egg plasma membranes.  相似文献   

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During antibody screening of a Taenia saginata oncosphere cDNA library a clone (R-Tso2) sharing a high degree of homology at both the DNA and amino acid levels with the small heat-shock protein (shsp) family was identified. The R-Tso2 clone was a full-length sequence (1162 bp) with an open reading frame of 945 bp and 314 amino acids, corresponding to a deduced molecular mass of 35.6 kDa and isoelectric point of 5.6. R-Tso2 had the highest degree of homology with the Schistosoma mansoni major egg antigens, showing the characteristic shsp 100 amino-acid sequence motif duplicated. The R-Tso2 expression product was not immuno-precipitated by any serum from a panel of serum samples obtained from bovine, porcine and human hosts suffering from either T. saginata or T. solium cysticercosis.  相似文献   

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The nucleotide sequence of 1981 bp cDNA containing the entire coding region of a human placental fructose-6-phosphate,2-kinase/fructose-2,6-bisphosphatase was determined. The sequence encodes 469 amino acids and, based on homology to the rat testis enzyme, appears to be the testis-type isozyme expressed in placenta. The enzyme was expressed in Escherichia coli BL21 (DE3) by using a T7 RNA polymerase-based expression system and purified to homogeneity. The expressed enzyme was bifunctional with specific activities of 75 and 80 mU/mg of kinase and phosphatase, respectively. Kinetic parameters of the expressed enzyme are similar to those of the rat testis enzyme.  相似文献   

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By catalyzing the rate-limiting step in adipose tissue lipolysis, hormone-sensitive lipase (HSL) is an important regulator of energy homeostasis. The role and importance of HSL in tissues other than adipose are poorly understood. We report here the cloning and expression of a testicular isoform, designated HSLtes. Due to an addition of amino acids at the NH2-termini, rat and human HSLtes consist of 1068 and 1076 amino acids, respectively, compared to the 768 and 775 amino acids, respectively, of the adipocyte isoform (HSLadi). A novel exon of 1.2 kb, encoding the human testis-specific amino acids, was isolated and mapped to the HSL gene, 16 kb upstream of the exons encoding HSLadi. The transcribed mRNA of 3.9 kb was specifically expressed in testis. No significant similarity with other known proteins was found for the testis-specific sequence. The amino acid composition differs from the HSLadi sequence, with a notable hydrophilic character and a high content of prolines and glutamines. COS cells, transfected by the 3.9-kb human testis cDNA, expressed a protein of the expected molecular mass (M(r) approximately 120,000) that exhibited catalytic activity similar to that of HSLadi. Immunocytochemistry localized HSL to elongating spermatids and spermatozoa; HSL was not detected in interstitial cells.  相似文献   

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F4/80 is a monoclonal antibody that recognizes a murine macrophage-restricted cell surface glycoprotein and has been extensively used to characterize macrophage populations in a wide range of immunological studies. Apart from the tightly regulated pattern of expression of the F4/80 antigen, little is known about its possible role in macrophage differentiation and function. We have sought to characterize the molecule at the molecular level, through the isolation of cDNA clones, and now describe the sequence of the F4/80 protein. The primary amino acid sequence demonstrates homology to two protein superfamilies. The NH2-terminal region consists of seven epidermal growth factor-like domains, separated by approximately 300 amino acids from a COOH-terminal region that shows homology to members of the seven transmembrane-spanning family of hormone receptors. The potential role of these distinct domains is discussed with respect to the possible function of the F4/80 molecule.  相似文献   

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A new Clostridium cellulovorans (strain ATCC 35296) endoglucanase gene engF has been isolated and sequenced. The gene contains 1671 bp and codes for a protein containing 557 amino acids and a mass of 60.1 kDa. A putative signal peptide of 29 amino acids is present and the mature protein has a mass of 57.1 kDa. EngF does not have amino acid sequence homology to previously isolated EngB and EngD, but does show sequence homology to family 5 glycosyl hydrolases from Bacillus, Erwinia carotovora, and C. acetobutylicum species. EngF is not a component of the cellulosome and does not contain a duplicated sequence (DS) at its C-terminal region. EngF is capable of binding to cellulose and hydrolyzing carboxymethylcellulose but not xylan. The cellulose binding domain (CBD) differs from types I, II and III CBDs and no obvious homology has been found to other CBD types. The maximum activity of EngF occurs at pH 5.5 and at 47 degrees C. Its properties suggest that EngF plays an ancillary role in the degradation of cellulosic materials.  相似文献   

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The protein composition of epididymal fluid and sperm extracts of rats treated with the nitroimidazole compound ornidazole was investigated by two-dimensional gel electrophoresis. Epididymal luminal fluid from the corpus and cauda regions of male animals rendered infertile by ornidazole treatment contained a prominent protein (contraception-associated protein 1, CAP1) with a molecular mass of approximately 25 kDa and an isoelectric point (pI) of 5.8; it was not found in fluids, but was present in sperm, from fertile vehicle-fed rats. Infrared matrix-assisted laser desorption/ionization mass spectrometry indicated that the molecular mass of CAP1 was 20420+/-120 daltons. Analysis of 17 amino acids demonstrated 49% homology to a diuretic hormone from an insect (Acheta domesticus). Densitometric quantitation of CAP1 on silver-stained gels indicated its presence in greater amounts in cauda than in corpus fluid from treated animals, whereas fluid from the rete testis lacked CAP1. In vitro incubations of tissue from the caput, corpus, and cauda epididymidal regions with [35S]methionine gave no hint that CAP1 was a secretion product of the epididymal epithelium. The absence of CAP1 from luminal fluid obtained from the sperm-depleted corpus epididymidis of efferent duct-ligated ornidazole-fed rats suggested a spermatozoal origin. CAP1 was present in spermatozoa from the caput epididymidis but not from the rete testis in control animals. Less CAP1 was present in detergent extracts of cauda sperm from ornidazole-treated rats than in sperm from control animals, suggesting a contraceptive-related displacement of protein from sperm to fluid. The association of ornidazole- and alpha-chlorohydrin-induced infertility with the presence of CAP1 in epididymal fluid, probably originating from spermatozoa, suggests a critical role for this protein in fertilization.  相似文献   

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The gene nprM encoding the calcium-dependent extracellular proteinase from Bacillus megaterium ATCC 14581 was cloned in the vector pBR322 and expressed in Escherichia coli HB101. The DNA sequence of the cloned 3.7 kb fragment revealed only one open reading frame consisting of 1686 bp with a coding capacity of 562 amino acid residues. A predicted Shine-Dalgarno (SD) sequence was observed 9 bp upstream from the presumptive translation start site (ATG). A possible promoter sequence (TAGACG for the -35 region and TATAAT for the -10 region) was found about 69 bp upstream of the ATG start site. The deduced amino acid sequence exhibited a 24 amino acid residue signal peptide and an additional polypeptide 'pro' sequence of 221 amino acids preceding the putative mature protein of 317 amino acid residues. Amino acid sequence comparison revealed 84.5% homology between the mature protein and that of a thermolabile neutral protease from B. cereus. It also shares 73% homology with the thermostable neutral proteases of B. thermoproteolyticus and B. stearothermophilus. The zinc-binding sites and the catalytic residues are completely conserved in all four proteases. NprM has a temperature optimum of 58 degrees C, a pH optimum of between 6.4 and 7.2, and is stimulated by calcium ions and inhibited by EDTA. These results indicate that the enzyme is a neutral (metallo-) protease.  相似文献   

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