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31.
Carla Emiliani Sabata Martino Antonio Orlacchio Roberta Vezza Giuseppe G. Nenci Paolo Gresele 《Cell biochemistry and function》1995,13(1):31-39
Granules containing acid hydrolases have been detected in human platelets but have not been thoroughly characterized. We have studied the activity and characteristics of glycohydrolases present in normal human platelets, evaluated their release upon stimulation with thrombin, and assessed the contribution of platelet - released lysosomal contents to the glycohydrolase activity present in normal serum. Platelets contained a remarkable glycohydrolase activity with a prevalence of β - N-acetylhexosaminidase. All glycohydrolases were released to some extent upon stimulation with thrombin and contributed to the glycohydrolase activity found in human serum. α-Mannosidase and α-galactosidase were partially inactivated after release by a mechanism as yet undefined. In addition, thrombin stimulation affects the intraplatelet isoenzyme pattern of β-N-acetylhexosaminidase by producing the appearance of a new form. 相似文献
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Livia R. Tanjung Gabrielle Whittle Bruce E. Shaw Garry A. Bloomfield Margaret E. Katz Brian F. Cheetham 《Anaerobe》2009,15(5):219-224
The Gram-negative anaerobic pathogen Dichelobacter nodosus is the principal causative agent of footrot in sheep. The intA, intB and intC elements are mobile genetic elements which integrate into two tRNA genes downstream from csrA (formerly glpA) and pnpA in the D. nodosus chromosome. CsrA homologues act as global repressors of virulence in several bacterial pathogens, as does polynucleotide phosphorylase, the product of pnpA. We have proposed a model in which virulence in D. nodosus is controlled in part by the integration of genetic elements downstream from csrA and pnpA, altering the expression of these putative global regulators of virulence. We describe here a novel integrated genetic element, the intD element, which is 32 kb in size and contains an integrase gene, intD, several genes related to genes on other integrated elements of D. nodosus, a type IV secretion system and a putative mobilisation region, suggesting that the intD element has a role in the transfer of other genetic elements. Most of the D. nodosus strains examined which contained the intD gene were benign, with intD integrated next to pnpA, supporting our previous observation that virulent strains of D. nodosus have the intA element next to pnpA. 相似文献
33.
George T. Lountos Brian P. Austin Sreedevi Nallamsetty David S. Waugh 《Protein science : a publication of the Protein Society》2009,18(2):467-474
Crystal structures of cleaved and uncleaved forms of the YscU cytoplasmic domain, an essential component of the type III secretion system (T3SS) in Yersinia pestis, have been solved by single‐wavelength anomolous dispersion and refined with X‐ray diffraction data extending up to atomic resolution (1.13 Å). These crystallographic studies provide structural insights into the conformational changes induced upon auto‐cleavage of the cytoplasmic domain of YscU. The structures indicate that the cleaved fragments remain bound to each other. The conserved NPTH sequence that contains the site of the N263‐P264 peptide bond cleavage is found on a β‐turn which, upon cleavage, undergoes a major reorientation of the loop away from the catalytic N263, resulting in altered electrostatic surface features at the site of cleavage. Additionally, a significant conformational change was observed in the N‐terminal linker regions of the cleaved and noncleaved forms of YscU which may correspond to the molecular switch that influences substrate specificity. The YscU structures determined here also are in good agreement with the auto‐cleavage mechanism described for the flagellar homolog FlhB and E. coli EscU. 相似文献
34.
Protein secretion in streptomycetes 总被引:1,自引:0,他引:1
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We have studied the modulation and pharmacological properties of two anion channels in T84 cells by recording single channel and transepithelial currents. One channel had an outwardly rectifying current-voltage I/V curve, was rarely active in cell-attached patches, and was unaffected by cAMP. The other channel had lower conductance (8.7 pS at 37°C) and a more ohmic I/V relationship. Exposure to cAMP increased the probability of observing low-conductance channel activity in cell-attached patches> 6-fold. Extracellular DIDS (4,4'-diisothiocyanatostilbene-2,2'-disulfonic acid) or IAA-94 (an indanyloxyacetic acid) inhibited the outward rectifier but did not affect the low-conductance channel or cAMP-stimulated transepithelial current. These results suggest the low-conductance Cl channel may contribute to apical membrane conductance during cAMP-stimulated secretion. 相似文献
37.
Carolina Elejalde-Palmett Ignacio Martinez San Segundo Imène Garroum Laurence Charrier Damien De Bellis Antonio Mucciolo Aurore Guerault Jie Liu Viktoria Zeisler-Diehl Asaph Aharoni Lukas Schreiber Bénédicte Bakan Mads H. Clausen Markus Geisler Christiane Nawrath 《Current biology : CB》2021,31(10):2111-2123.e9
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