These tools will no longer be maintained as of December 31, 2024. Archived website can be found here. PubMed4Hh GitHub repository can be found here. Contact NLM Customer Service if you have questions.


Pubmed for Handhelds

PUBMED FOR HANDHELDS

Search MEDLINE/PubMed

  • Title: Fcgamma receptor-mediated inhibition of human B cell activation: the role of SHP-2 phosphatase.
    Author: Koncz G, Pecht I, Gergely J, Sármay G.
    Journal: Eur J Immunol; 1999 Jun; 29(6):1980-9. PubMed ID: 10382761.
    Abstract:
    Co-clustering of the type II receptors binding the Fc part of IgG (FcgammaRIIb) and B cell receptors results in the translocation of cytosolic, negative regulatory molecules to the phosphorylated immunoreceptor tyrosine-based inhibitory motif (P-ITIM) of the FcgammaRIIb. SH2 domain-containing protein tyrosine phosphatases (SHP-1 and SHP-2), and the polyphosphoinositol 5'-phosphatase (SHIP) have been reported earlier to bind to murine FcgammaRIIb P-ITIM. However, neither the functional substrates of these enzymes, nor the mechanism of the inhibition are fully resolved. We show here that the human FcgammaRIIb binds SHP-2 when co-clustered with the B cell receptors, whereas its synthetic P-ITIM peptide bindes SHP-2 and SHIP in lysates of the Burkitt's lymphoma cell line BL41. The P-ITIM peptide binding enhances SHP-2 activity, resulting in dephosphorylation and release of P-ITIM-bound SHIP and Shc. Moreover, P-ITIM-bound SHP-2 dephosphorylates synthetic peptides corresponding to the sites of tyrosine phosphorylation on SHIP and Shc, indicating that these proteins are its potential substrates. Thus SHP-2-induced dephosphorylation may modulate the intracellular localization and/or activity of SHIP and Shc, thereby inhibiting further activation pathways which they mediate.
    [Abstract] [Full Text] [Related] [New Search]