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001-es BibID:BIBFORM054331
035-os BibID:PMID: 7797241
Első szerző:Sármay Gabriella
Cím:Interaction of signaling molecules with human FcγRIIb1 and the role of various FcγRIIb isoforms in B-cell regulation / Gabriella Sarmay, Zoltan Rozsnyay, Gabor Koncz, Janos Gergely
Dátum:1995
ISSN:0165-2478
Megjegyzések:The low-affinity type-IIb IgG Fc-binding receptors (Fc gamma RIIb) are expressed on B cells. When cross-linked with mIgM Fc gamma RIIb are known to down-regulate B-cell activation by interrupting signal transduction upstream from G-protein-activated events. We have studied Fc gamma RII isoforms expressed on resting and activated B cells and the interaction of Fc gamma RIIb1 with molecules transducing the antigen receptor-mediated signals. Expression of Fc gamma RII isoforms was studied by reverse transcription and polymerase chain reaction. Resting B cells express both Fc gamma RIIb2 and Fc gamma RIIb1 isoforms. Activation with anti-IgM or IL-4 induces the splicing of Fc gamma RIIb1 mRNA, while the alternative splicing of Fc gamma RIIb2 mRNA is down-regulated, resulting in the surface expression of Fc gamma RIIb1. Functional differences were found between the two isoforms in-inhibiting B-cell activation, suggesting that Fc gamma RIIb2 might influence the threshold of signals necessary for activation of resting B cells, while Fc gamma RIIb1 may regulate in later phases of antibody response.To explore the mechanism by which Fc gamma RII may uncouple antigen receptor-mediated signal transduction, we have investigated the association of signaling molecules with Fc gamma RII. Beside the protein tyrosine kinase (PTK) fyn, protein kinase C (PKC) was found to be co-isolated with Fc gamma RIIb1, suggesting a tight connection between these kinases and Fc gamma RII. We suggest that PKC might be responsible for the activation-induced phosphorylation of Fc gamma RII on serine residues. Signaling molecules responsible for the activation and localization of further elements of the activation pathway were also found to associate with Fc gamma RII. Among these RasGAP and Shc, the adapter molecule connecting PTK-triggered events to the Ras activation-dependent pathway were characterized. We suggest that Fc gamma RII may compete with the B-cell antigen receptor for key molecules regulating Ras activity, inhibiting thereby Ras activation.
Tárgyszavak:Orvostudományok Elméleti orvostudományok idegen nyelvű folyóiratközlemény külföldi lapban
HUMAN LYMPHOCYTES-B
RECEPTOR
PROTEIN
PHOSPHORYLATION
EXPRESSION
ACTIVATION
Megjelenés:Immunology Letters. - 44 : 2-3 (1995), p. 125-131. -
További szerzők:Rozsnyay Zoltán Koncz Gábor (1970-) (biológus, immunológus) Gergely János
Internet cím:Szerző által megadott URL
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