Effect of GTPγS on insulin binding and tyrosine phosphorylation in liver membranes and L6 muscle cells

E. Burdett, G. B. Mills, A. Klip

    Research output: Contribution to journalArticle

    18 Scopus citations

    Abstract

    Guanosine 5'-O-(3-thiotriphosphate) (GTPγS), a specific activator of G proteins, did not change the K(d) nor total binding of [125I]insulin in plasma membranes from rat liver. Insulin did not alter GTPγ35S binding nor polypeptide ADP ribosylation in crude and plasma membranes catalyzed either intrinsically or by cholera toxin. In L6 muscle cells, insulin caused tyrosine phosphorylation of a polypeptide of M(r) 160,000. Cell electroporation enabled testing of G protein action in this cellular system. Phosphorylation of the M(r) 160,000 polypeptide in these permeabilized cells was insulin and ATP dependent but other small molecules or ionic gradients were not essential. The reaction could not be mimicked by the G protein agonist GTPγS nor inhibited by the G protein antagonist guanosine 5'-O-(2-thiodiphosphate) (GDPβS). However, GTPγS effectively decreased insulin-mediated phosphorylation of this polypeptide. This suggests that the tyrosine kinase activity of the insulin receptor can be modulated by G protein agonists. It is concluded that cross talk between the insulin receptor and G proteins could not be demonstrated in isolated membranes by strategies that detect interactions between β-adrenergic receptors and G proteins. In contrast, in permeabilized cells, G protein-mediated regulation of the insulin receptor kinase activity could be detected.

    Original languageEnglish (US)
    Pages (from-to)C99-C108
    JournalAmerican Journal of Physiology - Cell Physiology
    Volume258
    Issue number1 27-1
    StatePublished - Feb 28 1990

    Keywords

    • adenosine 5'-diphosphate ribosylation
    • guanosine nucleotide-binding protein
    • insulin receptor
    • tyrosine kinase

    ASJC Scopus subject areas

    • Physiology
    • Cell Biology

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