Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0162871 (abdominal aortic aneurysm)
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Sperm capacitation is correlated with acquisition of fertilizing ability, and the molecular events underlying this process are only beginning to be understood. A number of membrane changes associated with capacitation have been documented. In this study we used lectin probes to identify changes in glycoprotein localization as a result of capacitation of mouse sperm. Eight lectins (LEA, PSA, PNA, AAA, UEA-1, WGA, STA, and TPA) stained regions of the mouse sperm head, tail, or both. No changes in tail staining patterns were detected when sperm were incubated under capacitating conditions. In contrast, 7 of 8 lectins tested showed clear shifts in staining patterns in the sperm head as a result of incubation under capacitating conditions. When staining patterns were quantified, a distinct heterogeneity within the sperm population was observed. Each lectin displayed 3 distinct staining patterns in both uncapacitated and capacitated sperm samples. The least common pattern represented the acrosome-reacted (AR) pattern, as independently assessed by lectin staining of ionophoretreated sperm that were >95% AR as judged by Coomassie staining. However, a reciprocal shift in the two predominant staining patterns was correlated with capacitation and suggests that changes in distribution of cell surface proteins during capacitation constitute part of the molecular changes which result in changes in sperm function acquired during this process.
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PMID:Sperm membrane dynamics assessed by changes in lectin fluorescence before and after capacitation. 1529 5

Intoxication by cytolethal distending toxin depends on assembly of CdtB, the active A component of this AB toxin, with the cell surface-binding (B) component, composed of the CdtA-CdtC heterodimer, to form the active holotoxin. Here we examine the cell surface binding properties of Escherichia coli-derived CdtA-II (CdtA-II(Ec)) and CdtC-II(Ec) and their capacity to provide a binding platform for CdtB-II(Ec). Using a flow cytometry-based binding assay, we demonstrate that CdtB-II(Ec) binds to the HeLa cell surface in a CdtA-II(Ec)- and CdtC-II(Ec)-dependent manner and that CdtA-II(Ec) and CdtC-II(Ec) compete for the same structure on the HeLa cell surface. Preincubation of cells with glycoproteins (thyroglobulin and fetuin), but not simple sugars, blocks surface binding of CdtA-II(Ec) and CdtC-II(Ec). Moreover, CdtA-II(Ec) and CdtC-II(Ec) bind immobilized fetuin and thyroglobulin as well as fucose and to a lesser degree N-acetylgalactoseamine and N-acetylglucoseamine. Removal of N- but not O-linked carbohydrates from fetuin and thyroglobulin prevents binding of CdtA-II(Ec) and CdtC-II(Ec) to these glycoproteins. In addition, removal of N- but not O-linked surface sugar attachments prevents CDT-II(Ec) intoxication. To characterize the cell surface ligand recognized by CdtA-II(Ec) and CdtC-II(Ec), lectins having various carbohydrate specificities were used to block CDT activity and the cell surface binding of CdtA-II(Ec) and CdtC-II(Ec). Pretreatment of cells with AAA, SNA-I, STA, UEA-I, GNA, and NPA partially or completely blocked CDT activity. AAA, EEA, and UEA-I lectins, all having specificity for fucose, blocked surface binding of CdtA-II(Ec) and CdtC-II(Ec). Together, our data indicate that CdtA-II(Ec) and CdtC-II(Ec) bind an N-linked fucose-containing structure on HeLa cells.
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PMID:Carbohydrate-binding specificity of the Escherichia coli cytolethal distending toxin CdtA-II and CdtC-II subunits. 1578 46