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Science. 1997 Jan 17;275(5298):394-7.

Linkage of G protein-coupled receptors to the MAPK signaling pathway through PI 3-kinase gamma.

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  • 1Max Planck Research Unit Molecular Cell Biology, Medical Faculty, University of Jena, 07747 Jena, Germany.


The tyrosine kinase class of receptors induces mitogen-activated protein kinase (MAPK) activation through the sequential interaction of the signaling proteins Grb2, Sos, Ras, Raf, and MEK. Receptors coupled to heterotrimeric guanine triphosphate-binding protein (G protein) stimulate MAPK through Gbetagamma subunits, but the subsequent intervening molecules are still poorly defined. Overexpression of phosphoinositide 3-kinase gamma (PI3Kgamma) in COS-7 cells activated MAPK in a Gbetagamma-dependent fashion, and expression of a catalytically inactive mutant of PI3Kgamma abolished the stimulation of MAPK by Gbetagamma or in response to stimulation of muscarinic (m2) G protein-coupled receptors. Signaling from PI3Kgamma to MAPK appears to require a tyrosine kinase, Shc, Grb2, Sos, Ras, and Raf. These findings indicate that PI3Kgamma mediates Gbetagamma-dependent regulation of the MAPK signaling pathway.

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