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61.
Characterization of a human homologue of the murine peripheral lymph node homing receptor 总被引:21,自引:11,他引:10
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Lymphocyte trafficking is a fundamental aspect of the immune system that allows B and T lymphocytes with diverse antigen recognition specificities to be exposed to various antigenic stimuli in spatially distinct regions of an organism. A lymphocyte adhesion molecule that is involved with this trafficking phenomenon has been termed the homing receptor. Previous work (Lasky, L., T. Yednock, M. Singer, D. Dowbenko, C. Fennie, H. Rodriguez, T. Nguyen, S. Stachel, and S. Rosen. 1989. Cell. 56:1045-1055) has characterized a cDNA clone encoding a murine homing receptor that is involved in trafficking of lymphocytes to peripheral lymph nodes. This molecule was found to contain a number of protein motifs, the most intriguing of which was a carbohydrate binding domain, or lectin, that is apparently involved in the adhesive interaction between murine lymphocytes and peripheral lymph node endothelium. In this study, we have used the murine cDNA clone to isolate a human homologue of this peripheral lymph node-specific adhesion molecule. The human receptor was found to be highly homologous to the murine receptor in overall sequence, but showed no sequence similarity to another surface protein that may be involved with human lymphocyte homing, the Hermes glycoprotein. The extracellular region of the human receptor contained an NH2 terminally located carbohydrate binding domain followed by an EGF-like domain and a domain containing two repeats of a complement binding motif. Transient cell transfection assays using the human receptor cDNA showed that it encoded a surface glycoprotein that cross reacted with a polyclonal antibody directed against the murine peripheral lymph node homing receptor. Interestingly, the human receptor showed a high degree of sequence homology to another human cell adhesion glycoprotein, the endothelial cell adhesion molecule ELAM. 相似文献
62.
Storage of apple fruits ( Pyrus malus L. cv. Golden Delicious) at different temperatures (0, 12 and 35°C) markedly altered the pattern of water freezing in the seeds. Higher temperatures of storage brought about a shift from the sequential to the discontinuous type of freezing in seeds, the low temperature exotherm (LTE) being much more pronounced than the high temperature one (HTE). The occurrence of LTE was highly correlated with embryo death. Fruit storage at higher temperatures also caused a decrease in the threshold super cooling temperature of seeds and of naked embryos, removed from the seed coat and endosperm. The decrease was less pronounced in naked embryos than in intact seeds. The results presented show that the frost resistance of apple seeds relies mainly on the supercooling ability of the embryos and is increased by the presence of seed coat and endosperm. The broad peak of the LTE indicates that, in contrast with other seeds and many super cooling organs, massive ice nucleation in apple seeds occurs within the embryo tissues and that extra organ freezing seems to be of less importance. Therefore, the increased super cooling ability of apple seeds, isolated from fruits stored at higher temperatures, seems to rely on those seed properties that protect embryo cells against heterogeneous ice nucleation. 相似文献
63.
64.
J B Gabrion H Barrière B Nguyen Than Dao M Chambard J Mauchamp F Regnouf L A Pradel 《European journal of cell biology》1990,52(2):282-290
A fodrin-like protein purified from porcine thyroid cells and characterized by its properties identical to those of pig brain spectrin (F. Regnouf et al., Eur. J. Biochem. 153, 313-319 (1985)) has been localized by immunofluorescence and electron immunocytochemistry in porcine and rat thyroid. Fodrin-like polypeptides were detected in subplasmalemmal meshworks of microfilaments attached to isolated or in situ plasma membranes. In resting cells, fodrin was found under apical and basolateral membrane domains, whereas it was always absent under the pseudopod membrane domain induced by acute TSH stimulation in vitro, using monolayers of porcine cultured cells attached to collagen permeable substrates, as well as in vivo, using rats intravenously treated with TSH. Thyroid fodrin could be involved in exocytosis and membrane stabilization which occurs during the formation of pseudopods induced by TSH stimulation. 相似文献
65.
The physical phenomenon of clathrate hydrate formation in protein-containing reversed micelles is described. Hydrate formation in reversed micelles is a method of adjusting the water to surfactant molar ratio, wo, which influences micellar size. Lipase and alpha-chymotrypsin encapsulated in large reversed micelles of high wo show significant enhancements in activity when the micelle size is reduced through hydrate formation. Alternate methods of micelle size adjustments also show enhancements in activity. The implications for improving the activity of such encapsulated enzymes recovered from fermentation media through phase transfer into reversed micelles are discussed. 相似文献
66.
O. Mendoza-Vega E. Keppi B. Bouchon M. Nguyen T. Achstetter 《Applied microbiology and biotechnology》1996,44(5):624-628
The recombinant outer-surface protein A with an N-terminally truncated form (des-Cys1-OspA) from the Lyme disease spirochete Borrelia burgdorferi was expressed in Saccharomyces cerevisiae at high production levels. Since the recombinant vaccine candidate expressed in Escherichia coli exhibits low production yields and the purification of lipoproteins appears to be difficult, we have investigated the secretion of a soluble recombinant OspA in the yeast S. cerevisiae. In this way, a Leu+ derivative of S. cerevisiae cI3ABYS86 was used as the host strain transformed with an expression plasmid containing the gene encoding des-Cys1-OspA and driven by the MF1 promoter. The fed-batch culture results revealed that an efficient secretion of des-Cys1-OspA is obtained with a high production level of about 2.1 g 1–1 at a cell density of 101 g 1–1 cell dry weight. The accumulation of recombinant protein in the supernatant exceeds 6% of the total yeast proteins when estimated by sodium dodecyl sulphate/polyacrylamide gel electrophoresis. Moreover, des-Cys1-OspA showed lower solubilities at high cell densities and, as a consequence, a fraction of the recombinant protein precipitated. An internal cleavage of the MF1 pro::des-Cys1-OspA precursor was also detected. However, in this case the cleavage occurred at a frequency such that the large amounts of the secreted des-Cys1-OspA could be employed for the evaluation of an immunogenic effect on animal immunization. These studies will extend the knowledge of the usefulness of OspA as a vaccine for Lyme borreliosis. 相似文献
67.
68.
PI 3-kinase is a dual specificity enzyme: autoregulation by an intrinsic protein-serine kinase activity. 总被引:36,自引:6,他引:30
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![点击此处可从《The EMBO journal》网站下载免费的PDF全文](/ch/ext_images/free.gif)
R Dhand I Hiles G Panayotou S Roche M J Fry I Gout N F Totty O Truong P Vicendo K Yonezawa et al. 《The EMBO journal》1994,13(3):522-533
Phosphatidylinositol 3-kinase (PI 3-kinase) has a regulatory 85 kDa adaptor subunit whose SH2 domains bind phosphotyrosine in specific recognition motifs, and a catalytic 110 kDa subunit. Mutagenesis of the p110 subunit, within a sequence motif common to both protein and lipid kinases, demonstrates a novel intrinsic protein kinase activity which phosphorylates the p85 subunit on serine at a stoichiometry of approximately 1 mol of phosphate per mol of p85. This protein-serine kinase activity is detectable only upon high affinity binding of the p110 subunit with its unique substrate, the p85 subunit. Tryptic phosphopeptide mapping revealed that the same major peptide was phosphorylated in p85 alpha both in vivo in cultured cells and in the purified recombinant enzyme. N-terminal sequence and mass analyses were used to identify Ser608 as the major phosphorylation site on p85 alpha. Phosphorylation of the p85 subunit at this serine causes an 80% decrease in PI 3-kinase activity, which can subsequently be reversed upon treatment with protein phosphatase 2A. These results have implications for the role of inter-subunit serine phosphorylation in the regulation of the PI 3-kinase in vivo. 相似文献
69.
Occurrence of Shiga-like toxin-producing Escherichia coli in retail fresh seafood, beef, lamb, pork, and poultry from grocery stores in Seattle, Washington. 总被引:5,自引:3,他引:2
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M Samadpour J E Ongerth J Liston N Tran D Nguyen T S Whittam R A Wilson P I Tarr 《Applied microbiology》1994,60(3):1038-1040
Fresh meat, poultry, and seafood purchased from Seattle area grocery stores were investigated for the presence of Shiga-like toxin-producing Escherichia coli by using DNA probes for Shiga-like toxin (SLT) genes I and II. Of the 294 food samples tested, 17% had colonies with sequence homology to SLT I and/or SLT II genes. 相似文献
70.
The Bacillus subtilis nucleoid-associated protein HPB12 strongly compacts DNA. 总被引:3,自引:1,他引:2
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![点击此处可从《Journal of bacteriology》网站下载免费的PDF全文](/ch/ext_images/free.gif)
B Arnold-Schulz-Gahmen V Salti-Montesanto J Nguyen L Hirschbein F Le Hgarat 《Journal of bacteriology》1994,176(1):50-60
The HPB12 protein from the nucleoid of Bacillus subtilis was previously described, and its DNA binding properties have been reported previously (V. Salti, F. Le Hégarat, and L. Hirschbein, Biochim. Biophys. Acta 1009:161-167, 1989). The DNA-HPB12 complexes were examined by electron microscopy. They appeared as short, slightly curved rods whereas naked DNA showed no compaction. Since only a small number of complexes with an intermediate degree of folding were observed, it appears that the nucleoid-associated protein HPB12 binds cooperatively to DNA, confirming Salti et al. (V. Salti, F. Le Hégarat, and L. Hirschbein, Biochim. Biophys. Acta 1009:161-167, 1989), and gives rise to a tightly compacted DNA-protein complex. N-terminal sequencing of purified HPB12 showed that all but one of the first 26 amino acids were identical to those of the L24 ribosomal protein. 相似文献