共查询到20条相似文献,搜索用时 45 毫秒
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Asako Ando Yara Yukie Kikuti Atsuko Shigenari Hisako Kawata Naoaki Okamoto Takashi Shiina Lei Chen Toshimichi Ikemura Kuniya Abe Minoru Kimura Hidetoshi Inoko 《Genomics》1996,35(3):600
cDNA clones corresponding to theHKE4andHKE6genes at the centromeric end of the HLA region on human chromosome 6p21.3 were isolated and characterized. The predicted amino acid sequences of HKE4 and HKE6 exhibited 81.5 and 85.6% identity to the mouse homologues, Ke4 and Ke6, respectively.HKE4may encode a membrane protein with histidine-rich charge clusters. HKE6 possesses remarkable amino acid sequence conservation with several bacterial proteins with oxidoreductase function and also shows significant homology with the two unique functional domains containing the nucleotide cofactor binding site and the consensus motif characteristic of the members of the superfamily of short-chain alcohol dehydrogenases such as human and rat steroid and prostaglandin dehydrogenases. 相似文献
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Amy M. Boulden Robert S. Foote G. Scott Fleming Sankar Mitra 《Journal of biosciences》1987,11(1-4):215-224
DNA-O6-methylguanine methyltransferase was purified from the nuclear fraction of fresh human placenta using ammonium sulphate precipitation,
gel filtration, affinity chromatography on DNA-cellulose and hydroxyapatite. The methyltransferase preparation was approximately
1–2% pure based on specific activity, and was free of nucleic acids. The protein reacts stoichiometrically with O6-methylguanine in DNA with apparent second-order kinetics. The human methyltransferase has a pH optimum of about 8.5, similar
to that of the corresponding rat and mouse proteins. NaCl inhibits the reaction in a concentration-dependent fashion. The
human protein, like the rodent andE. coli methyltransferases, needs no cofactor. While lmM MnCl2, lmM spermidine, 5mM MgCl2 and 10 mM EDTA individually do not significantly inhibit the initial rate of reaction, the protein is nearly completely inactive
in 5 mM A1Cl3 or FeCl2 or 10 mM spermidine. The initial rate of reaction increases as a function of temperature at least up to 42°. The reaction
is inhibited by DNA in a concentration-dependent manner, with single-stranded DNA being more inhibitory than duplex DNA. 相似文献
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The second division of the gut precursor E cells is lethally accelerated during Caenorhabditis elegans gastrulation by mutations in the emb-5 gene, which encodes a presumed nuclear protein. We have isolated suppressor mutations of the temperature-sensitive allele
emb-5(hc61), screened for them among dpy and other mutations routinely used as genetic markers, and identified eight emb-5 suppressor genes. Of these eight suppressor genes, at least four encode extracellular matrix proteins, i.e., three collagens
and one proteoglycan. The suppression of the emb-5 gastrulation defect seemed to require the maternal expression of the suppressors. Phenotypically, the suppressors by themselves
slowed down early embryonic cell divisions and corrected the abnormal cell-division sequence of emb-5 mutant embryos. We propose an indirect stress-response mechanism to be the main cause of the suppression because: (1) none
of these suppressors is specific, either to particular temperature-sensitive emb-5 alleles or to the emb-5 gene; (2) suppressible alleles of genes, reported here or elsewhere, are temperature sensitive or weak; (3) the suppression
is not strong but marginal; (4) the suppression itself shows some degree of temperature dependency; and (5) none of the extracellular
matrix proteins identified here is known to be expressed in oocytes or early embryos, despite the present observation that
the suppression is maternal.
Received: 19 August 1997 / Accepted: 11 December 1997 相似文献
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By use of primers specific for human T-cell receptor (Tcr) Vb6 gene elements, a typing system for Tcr Vb variability in several artiodactyl species has been established. The amplified polymorphic locus is homologous to the human Vb6 gene element. Like the human counterpart, the artiodactyl Vb6 element contains a polymorphic intronic simple (gt)n repeat stretch. Extensive length polymorphism of this simple repeat sequence in some artiodactyls should allow efficient association studies in a multiplex approach, especially including MHC class II genes. On the protein level the Vb regions display little variability in the inter-species comparison among artiodactyls. The amino acid substitutions are not concentrated in the putative complementarity determining regions, suggesting evolutionary conservation. In addition, the simple repetitive element has been preserved in the same genomic location for more than 7×107 years. Similar evolutionary persistence has already been demonstrated for a (gt)n(ga)m repeat stretch in the second intron of the MHC-DRB locus. The reasons for these parallel developments in evolution are so far not clear, but they may point to a biological meaning if not function of the intronic simple repeat element. 相似文献
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In a screen designed to identify genes expressed preferentially in retina, we identified a cDNA encoding the human ortholog of rat STXBP1 (n-Sec1, Munc-18-1, rbSec1), a protein implicated in vesicle trafficking and neurotransmitter release. This protein also has similarity toDrosophilaRop (64% aa identity) andCaenorhabditis elegansUNC-18 (58% aa identity). The major human cDNA encodes a protein of 594 amino acids which has 100% amino acid identity with its rat and murine counterparts. Additionally, there is an alternative splice form in humans, arising from the inclusion of an additional exon, which encodes a protein of 603 amino acids and is also 100% identical to the corresponding rat isoform. We found expression of the shorter cDNA in all tissues and cell lines we examined with highest levels in retina and cerebellum. By RT-PCR analysis, we found expression of the longer cDNA in neural tissues only. We mapped the structural gene to 9q34.1, a region without obvious candidate phenotypes. However, due to its evolutionary conservation and abundant expression in retina and brain, STXBP1 should be considered a candidate gene for retinal and/or neural disorders mapping to 9q34.1. 相似文献
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The murine CC chemokine, 6C-kine, inhibits tumor growth and angiogenesis in a human lung cancer SCID mouse model 总被引:5,自引:0,他引:5
Arenberg DA Zlotnick A Strom SR Burdick MD Strieter RM 《Cancer immunology, immunotherapy : CII》2001,49(11):587-592
The recently described CC chemokine, 6C-kine, is unique in that it contains -six rather than the usual four conserved cysteines
typical of this family. Furthermore, murine 6C-kine binds to one of the CXC chemokine receptors CXCR3, in addition to its
other known receptor CCR7. We have shown that two other ligands of CXCR3, IP-10 and MIG, are potent inhibitors of tumor growth
in severe combined immunodeficiency (SCID) mice. We postulated that murine 6C-kine may also inhibit tumor growth via inhibition
of angiogenesis in this model. SCID mice (n=6 per group) inoculated with A549 human lung cancer cells were treated with either 6C-kine (100 ng intra-tumor injection
every other day) or control protein for 8 weeks. Tumors from murine 6C-kine-treated mice (288 ± 26 mm3) were significantly smaller than tumors from control treated mice (788 ± 156 mm3, P=0.005). Additionally, murine 6C-kine reduced metastases compared with controls (0.5 ± 0.3 vs 3.0 ± 1.2 metastases per animal,
P=0.05). Tumor vascularity (as assessed by vessel density counting) was reduced in murine 6C-kine-treated mice compared with
controls. Murine 6C-kine had no direct effect on proliferation of A549 cells, and there were no differences in the infiltration
of leukocyte sub-populations, assessed by flow cytometry, in the treatment groups. Interestingly, human 6C-kine, unlike murine
6C-kine, does not bind CXCR3 and had no anti-tumor effect in the same model. These data suggest that murine 6C-kine has anti-tumor
effects independent of its leukocyte-recruiting activity. Furthermore, while not confirmatory, these data lend further support
to the fact that CXCR3 may be the receptor for angiostatic CXC chemokines.
Received: 15 June 2000 / Accepted: 18 August 2000 相似文献
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Coupling factor 6 (F6) is a component of mitochondrial ATP synthase which is required for the interactions of the catalytic and proton-translocating segments. A human fetal muscle cDNA clone encoding this protein was isolated by screening a lambda gt10 library with oligodeoxyribonucleotide probes. The 497-bp F6 cDNA included a 96-bp segment that delineated a presequence of 32 amino acids (aa) in the precursor protein, and 140 bp of 3'-untranslated sequence. The remainder of the cDNA sequence coded for a mature human F6 protein of 76 aa. The deduced primary aa sequence showed 81% homology to that of bovine F6, differing in 14 aa. Almost all of these aa substitutions were conservative and comparison of the hydropathy profiles revealed a similar pattern. 相似文献
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We cloned the cDNA and genomic DNA encoding for Izumo1 of cashmere goat (Capra hircus) and sheep (Ovis aries). Analysis of 4.6 kb Izumo1 genomic sequences in sheep and goat revealed a canonical open reading frame (ORF) of 963 bp spliced
by eight exons. Sheep and goat Izumo1 genes share >99% identity at both DNA and protein levels and are also highly homologous to the orthologues in cattle, mouse,
rat and human. Extensive cloning and analysis of Izumo1 cDNA revealed three (del 69, del 182 and del 217) and two (del 69
and ins 30) alternative splicing isoforms in goat and sheep, respectively. All of the isoforms are derived from splicing at
typical GT-AG sites leading to partial or complete truncation of the immunoglobulin (Ig)-like domain. Bioinformatics analysis
showed that caprine and ovine Izumo1 proteins share similar structure with their murine orthologue. There are a signal peptide
at the N-terminus (1–22 aa), a transmembrane domain at the C-terminus (302–319 aa), and an extracellular Ig-like region in
the middle (161–252 aa) with a putative N-linked glycosylation site (N205-N-S). Alignment of Izumo1 protein sequences among 15 mammalian species displayed several highly conserved regions, including
LDC and YRC motifs with cysteine residues for potential disulfide bridge formation, CPNKCG motif upstream of the Ig-like domain,
GLTDYSFYRVW motif upstream of the putative N-linked glycosylation site, and a number of scattered cysteine residues. These
distinctive features are very informative to pinpoint the important gene motifs and functions. The C-terminal regions, however,
are more variable across species. Izumo1 cDNA sequences of goat, sheep, and cow were found to be largely homologous, and the
molecular phylogenetic analysis is consistent with their morphological taxonomy. This implies the Izumo1 gene evolves from the same ancestor, and the mechanism of sperm–egg fusion in mammals may be under the same principle in
which Izumo1 plays an important role. 相似文献