G protein coupling of antigen receptor-stimulated polyphosphoinositide hydrolysis in B cells |
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Authors: | M M Harnett G G Klaus |
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Institution: | National Institute for Medical Research, London, England. |
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Abstract: | Cross-linking of the IgM and IgD Ag-R on mature B lymphocytes provokes the rapid hydrolysis of phosphatidylinositol 4,5-bisphosphate. We show here that in permeabilized, 3H]inositol-labeled mouse B cells the nonhydrolyzable GTP analogue GTP gamma S induces release of inositol phosphates, including inositol trisphosphate. The response is markedly augmented by the addition of polyclonal anti-Ig or anti-mu or anti-delta mAb. Inositol phosphate release provoked in intact B cells by any of the anti-receptor antibodies was not inhibited by pertussis toxin and only partially inhibited by cholera toxin. The results therefore indicate that both IgM- and IgD-R on B cells are coupled to the polyphosphoinositide-specific phosphodiesterase by one or more G proteins, which have yet to be identified. |
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