The PI3-kinase serine kinase phosphorylates its p85 subunit and IRS-1 in Pi3-kinase/IRS-1 complexes

Gregory G. Freund, James G. Wittig, Robert A. Mooney

    Research output: Contribution to journalArticlepeer-review

    Abstract

    Insulin receptor tyrosine kinase activity accounts for tyrosine phosphorylation of insulin receptor substrate-1 (IRS-1), but the serine kinase(s) responsible for serine phosphorylation of IRS-1 is(are) unknown. In vitro kinase assays performed on PI3-kinase and IRS-1 immunoprecipitates demonstrated insulin-dependent serine phosphorylation of IRS-1. IRS-1 was associated with both insulin-dependent and independent serine kinases. Only the insulin-dependent serine kinase preferred Mn2+ over Mg2+ and was recovered from cell lysates containing dithiothreitol. In complexes of tyrosine phosphorylated recombinant IRS-1 and PI3-kinase, phosphorylation of IRS-1 was associated with decreased phosphorylation of the p85 subunit of PIS-kinase. These results are consistent with PI3-kinase being responsible for insulin-dependent serine phosphorylation of IRS-1 and suggest that this phosphorylation reaction may affect functions of both IRS-1 and the PI3-kinase.

    Original languageEnglish (US)
    Pages (from-to)272-278
    Number of pages7
    JournalBiochemical and Biophysical Research Communications
    Volume206
    Issue number1
    DOIs
    StatePublished - Jan 5 1995

    ASJC Scopus subject areas

    • Biophysics
    • Biochemistry
    • Molecular Biology
    • Cell Biology

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