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: Tyrosine kinase and CD45 tyrosine phosphatase activity mediate p21ras activation in B cells stimulated through the antigen receptor.
    Author: Kawauchi K, Lazarus AH, Rapoport MJ, Harwood A, Cambier JC, Delovitch TL.
    Journal: J Immunol; 1994 Apr 01; 152(7):3306-16. PubMed ID: 7511643.
    Abstract:
    Cross-linking of the Ag receptor (AgR) induces intracellular signaling events in B cells, such as p21ras activation, that lead to their proliferation and differentiation. This event is accompanied by the tyrosine phosphorylation of the p21ras-associated GTPase-activating protein p120 ras.GAP, raising the possibility that AgR-stimulated p21ras activity is regulated by protein tyrosine kinases (PTKs) and protein tyrosine phosphatases (PTPases) in B cells. To test this possibility, we examined the effects of PTK and PTPase inhibitors on protein tyrosine phosphorylation and p21ras activation induced by AgR cross-linking in TNP-specific TA3 7.9 murine B lymphoma cells. Although AgR-induced protein tyrosine phosphorylation was inhibited by the PTK inhibitors genistein and herbimycin A, it was enhanced by exposure to the PTPase inhibitor phenylarsine oxide (PAO). Cross-linking of the AgR by Ag or F(ab')2 anti-IgM induced a rapid (within 5 min) two- to threefold increase in p21ras activation in 7.9 B cells. Interestingly, a second peak of p21ras activation was evident at approximately 40 min after stimulation. Genistein and herbimycin A and PAO each blocked AgR-stimulated p21ras activation. Similarly, Ag-induced p21ras activation was inhibited by pretreatment of 7.9 B cells with an anti-CD45 mAb (detects the 220-kDa B cell isoform of CD45). Moreover, p21ras activation was induced by Ag and F(ab')2 anti-IgM in CD45+ but not CD45- J558L microns 3 B cells. These data indicate that p21ras activation induced by AgR cross-linking in B cells is regulated by both PTK and CD45 PTPase activities.
    [Abstract] [Full Text] [Related] [New Search]