title: Crystal structure and functional analysis of Ras binding to its effector phosphoinositide 3-kinase gamma.
abstract: 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.
authors.affiliation: MRC Laboratory of Molecular Biology Hills Road CB2 2QH, Cambridge, United Kingdom.
authors.forename: M E
authors.initials: ME
authors.lastname: Pacold
authors.forename: S
authors.initials: S
authors.lastname: Suire
authors.forename: O
authors.initials: O
authors.lastname: Perisic
authors.forename: S
authors.initials: S
authors.lastname: Lara-Gonzalez
authors.forename: C T
authors.initials: CT
authors.lastname: Davis
authors.forename: E H
authors.initials: EH
authors.lastname: Walker
authors.forename: P T
authors.initials: PT
authors.lastname: Hawkins
authors.forename: L
authors.initials: L
authors.lastname: Stephens
authors.forename: J F
authors.initials: JF
authors.lastname: Eccleston
authors.forename: R L
authors.initials: RL
authors.lastname: Williams
mesh_terms: D000818:Animals; D001665:Binding Sites; D019556:COS Cells; D058544:Class Ib Phosphatidylinositol 3-Kinase; D018360:Crystallography, X-Ray; D016244:Guanosine 5'-O-(3-Thiotriphosphate) / Q000737:chemistry / Q000378:metabolism; D006801:Humans; D007527:Isoenzymes / Q000737:chemistry* / Q000378:metabolism*; D007700:Kinetics; D008958:Models, Molecular; D016297:Mutagenesis, Site-Directed; D009504:Neutrophils / Q000378:metabolism; D019869:Phosphatidylinositol 3-Kinases / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D011485:Protein Binding; D011487:Protein Conformation; D017434:Protein Structure, Tertiary; D018631:ras Proteins / Q000737:chemistry / Q000378:metabolism*
chemical_list: D007527:Isoenzymes; D016244:Guanosine 5'-O-(3-Thiotriphosphate); D019869:Phosphatidylinositol 3-Kinases; D058544:Class Ib Phosphatidylinositol 3-Kinase; C546760:PIK3CG protein, human; D018631:ras Proteins