Crystal structure and functional analysis of Ras binding to its effector phosphoinositide 3-kinase gamma

Cell. 2000 Dec 8;103(6):931-43. doi: 10.1016/s0092-8674(00)00196-3.


Ras activation of phosphoinositide 3-kinase (PI3K) is important for survival of transformed cells. We find that PI3Kgamma is strongly and directly activated by H-Ras G12V in vivo or by GTPgammaS-loaded H-Ras in vitro. We have determined a crystal structure of a PI3Kgamma/Ras.GMPPNP complex. A critical loop in the Ras binding domain positions Ras so that it uses its switch I and switch II regions to bind PI3Kgamma. Mutagenesis shows that interactions with both regions are essential for binding PI3Kgamma. Ras also forms a direct contact with the PI3Kgamma catalytic domain. These unique Ras/PI3Kgamma interactions are likely to be shared by PI3Kalpha. The complex with Ras shows a change in the PI3K conformation that may represent an allosteric component of Ras activation.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Binding Sites
  • COS Cells
  • Class Ib Phosphatidylinositol 3-Kinase
  • Crystallography, X-Ray
  • Guanosine 5'-O-(3-Thiotriphosphate) / chemistry
  • Guanosine 5'-O-(3-Thiotriphosphate) / metabolism
  • Humans
  • Isoenzymes / chemistry*
  • Isoenzymes / metabolism*
  • Kinetics
  • Models, Molecular
  • Mutagenesis, Site-Directed
  • Neutrophils / metabolism
  • Phosphatidylinositol 3-Kinases / chemistry*
  • Phosphatidylinositol 3-Kinases / genetics
  • Phosphatidylinositol 3-Kinases / metabolism*
  • Protein Binding
  • Protein Conformation
  • Protein Structure, Tertiary
  • ras Proteins / chemistry
  • ras Proteins / metabolism*


  • Isoenzymes
  • Guanosine 5'-O-(3-Thiotriphosphate)
  • Phosphatidylinositol 3-Kinases
  • Class Ib Phosphatidylinositol 3-Kinase
  • PIK3CG protein, human
  • ras Proteins

Associated data

  • PDB/1HE8