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91.
92.
Synthesis of the modified thymine base beta-D-glucosyl-hydroxymethyluracil, or J, within telomeric DNA of Trypanosoma brucei correlates with the bloodstream-form-specific epigenetic silencing of telomeric variant surface glycoprotein genes involved in antigenic variation. The mechanism of developmental and telomeric-specific regulation of J synthesis is unknown. We have previously identified a J binding protein (JBP1) involved in propagating J synthesis. We have now identified a homolog of JBP1, JBP2, containing a domain related to the SWI2/SNF2 family of chromatin remodeling proteins that is upregulated in bloodstream form cells and interacts with nuclear chromatin. We show that expression of JBP2 in procyclic form cells leads to de novo J synthesis within telomeric regions of the chromosome and that this activity is inhibited after mutagenesis of conserved residues critical for SWI2/SNF2 function. We propose a model in which chromatin remodeling by JBP2 regulates the initial sites of J synthesis within bloodstream form trypanosome DNA, with further propagation and maintenance of J by JBP1. 相似文献
93.
Human cyclin E, a new cyclin that interacts with two members of the CDC2 gene family. 总被引:103,自引:0,他引:103
A new human cyclin, named cyclin E, was isolated by complementation of a triple cln deletion in S. cerevisiae. Cyclin E showed genetic interactions with the CDC28 gene, suggesting that it functioned at START by interacting with the CDC28 protein. Two human genes were identified that could interact with cyclin E to perform START in yeast containing a cdc28 mutation. One was CDC2-HS, and the second was the human homolog of Xenopus CDK2. Cyclin E produced in E. coli bound and activated the CDC2 protein in extracts from human G1 cells, and antibodies against cyclin E immunoprecipitated a histone H1 kinase from HeLa cells. The interactions between cyclin E and CDC2, or CDK2, may be important at the G1 to S transition in human cells. 相似文献
94.
Sakarya S Rifat S Zhou J Bannerman DD Stamatos NM Cross AS Goldblum SE 《Glycobiology》2004,14(6):481-494
The amount of sialic acid on the surface of the neutrophil (PMN) influences its ability to interact with other cells. PMN activation with various stimuli mobilizes intracellular sialidase to the plasma membrane, where it cleaves sialic acid from cell surfaces. Because enhanced PMN adherence, spreading, deformability, and motility each are associated with surface desialylation and are critical to PMN diapedesis, we studied the role of sialic acid on PMN adhesion to and migration across pulmonary vascular endothelial cell (EC) monolayers in vitro. Neuraminidase treatment of either PMN or EC increased adhesion and migration in a dose-dependent manner. Neuraminidase treatment of both PMNs and ECs increased PMN adhesion to EC more than treatment of either PMNs or ECs alone. Moreover, neuraminidase treatment of ECs did not change surface expression of adhesion molecules or release of IL-8 and IL-6. Inhibition of endogenous sialidase by either cross-protective antineuraminidase antibodies (45.5% inhibition) or competitive inhibition with pseudo-substrate (41.2% inhibition) decreased PMN adhesion to ECs; the inhibitable sialidase activity appeared to be associated with activated PMNs. Finally, EC monolayers preincubated with activated PMNs became hyperadhesive for subsequently added resting PMNs, and this hyperadhesive state was mediated through endogenous PMN sialidase activity. Blocking anti-E-selectin, anti-CD54 and anti-CD18 antibodies decreased PMN adhesion to tumor necrosis factor-activated ECs but not to PMN-treated ECs. These data implicate desialylation as a novel mechanism through which PMN-EC adhesion can be regulated independent of de novo protein synthesis or altered adhesion molecule expression. The ability of activated PMNs, through endogenous sialidase activity, to render the EC surface hyperadherent for unstimulated PMNs may provide for rapid amplification of the PMN-mediated host response. 相似文献
95.
96.
Moores CA Perderiset M Kappeler C Kain S Drummond D Perkins SJ Chelly J Cross R Houdusse A Francis F 《The EMBO journal》2006,25(19):4448-4457
Doublecortin is a neuronal microtubule-stabilising protein, mutations of which cause mental retardation and epilepsy in humans. How doublecortin influences microtubule dynamics, and thereby brain development, is unclear. We show here by video microscopy that purified doublecortin has no effect on the growth rate of microtubules. However, it is a potent anti-catastrophe factor that stabilises microtubules by linking adjacent protofilaments and counteracting their outward bending in depolymerising microtubules. We show that doublecortin-stabilised microtubules are substrates for kinesin translocase motors and for depolymerase kinesins. In addition, doublecortin does not itself oligomerise and does not bind to tubulin heterodimers but does nucleate microtubules. In cells, doublecortin is enriched at the distal ends of neuronal processes and our data raise the possibility that the function of doublecortin in neurons is to drive assembly and stabilisation of non-centrosomal microtubules in these doublecortin-enriched distal zones. These distinct properties combine to give doublecortin a unique function in microtubule regulation, a role that cannot be compensated for by other microtubule-stabilising proteins and nucleating factors. 相似文献
97.
Zachary A. Bornholdt Andrew S. Herbert Chad E. Mire Shihua He Robert W. Cross Anna Z. Wec Dafna M. Abelson Joan B. Geisbert Rebekah M. James Md Niaz Rahim Wenjun Zhu Viktoriya Borisevich Logan Banadyga Bronwyn M. Gunn Krystle N. Agans Ariel S. Wirchnianski Eileen Goodwin Kevin Tierney John M. Dye 《Cell host & microbe》2019,25(1):49-58.e5
98.
Cross Adam T. Stevens Jason C. Sadler Rohan Moreira-Grez Benjamin Ivanov Dmitry Zhong Hongtao Dixon Kingsley W. Lambers Hans 《Plant and Soil》2021,460(1-2):163-176
Plant and Soil - In water-limited areas, shrubs influence biological soil crust (biocrust) composition and diversity via soil microenvironment alterations and through modifying biotic interactions... 相似文献
99.
人TRAIL基因cDNA的克隆及其在COS—7细胞中的表达 总被引:1,自引:0,他引:1
TRAIL(TNFrelatedapoptosisinducingligand)是最近克隆的肿瘤坏死因子(TNF)家族的新成员,由于它的蛋白质结构和生物学效应类似于FAS/APO1L,因此,也被称为APO2L。在低浓度下,TRAIL能迅速地诱导多种肿瘤细胞系的?.. 相似文献
100.
Optimizing and characterizing alignment of oriented lipid bilayers containing gramicidin D. 下载免费PDF全文
31P NMR spectroscopy and optical microscopy have been used to characterize samples of gramicidin D in oriented lipid bilayers. Correlations have been made between the defect structures observed under crossed polarizers by optical microscopy and characteristic features of 31P NMR spectra. The sample preparation protocol has been improved using these techniques to achieve minimal dispersion of the bilayer normal and minimal amounts of unoriented sample. The molar ratio of gramicidin to dimyristoyl-phosphatidylcholine, the extent of hydration, and the cosolubilizing solvent system were used as the protocol variables. While hydration level and solvent system had profound effects on the sample orientation the molar ratio did not. However, the 31P chemical shift anisotropy is very sensitive to the molar ratio and can be used as an in situ method for determining the molar ratio. 相似文献