Phosphatidylinositol 3-kinase is an early intermediate in the G beta gamma-mediated mitogen-activated protein kinase signaling pathway.

Journal Article (Journal Article)

The beta gamma-subunit of Gi mediates mitogen-activated protein (MAP) kinase activation through a signaling pathway involving Shc tyrosine phosphorylation, subsequent formation of a multiprotein complex including Shc, Grb2, and Sos, and sequential activation of Ras, Raf, and MEK. The mechanism by which G beta gamma mediates tyrosine phosphorylation of Shc, however, is unclear. This study assesses the role of phosphatidylinositol 3-kinase (PI-3K) in G beta gamma-mediated MAP kinase activation. We show that Gi-coupled receptor- and G beta gamma-stimulated MAP kinase activation is attenuated by the PI-3K inhibitors wortmannin and LY294002 or by over expression of a dominant negative mutant of the p85 subunit of PI-3K. Wortmannin and LY294002 also inhibit Gi-coupled receptor-stimulated Ras activation. The PI-3K inhibitors do not affect MAP kinase activation stimulated by over-expression of Sos, a constitutively active mutant of Ras, or a constitutively active mutant of MEK. These results demonstrate that PI-3K activity is required in the G beta gamma-mediated MAP kinase signaling pathway at a point upstream of Sos and Ras activation.

Full Text

Duke Authors

Cited Authors

  • Hawes, BE; Luttrell, LM; van Biesen, T; Lefkowitz, RJ

Published Date

  • May 24, 1996

Published In

Volume / Issue

  • 271 / 21

Start / End Page

  • 12133 - 12136

PubMed ID

  • 8647803

International Standard Serial Number (ISSN)

  • 0021-9258

Digital Object Identifier (DOI)

  • 10.1074/jbc.271.21.12133


  • eng

Conference Location

  • United States