title: Structural insights into phosphoinositide 3-kinase catalysis and signalling.
abstract: Phosphoinositide 3-kinases (PI3Ks) are ubiquitous lipid kinases that function both as signal transducers downstream of cell-surface receptors and in constitutive intracellular membrane and protein trafficking pathways. All PI3Ks are dual-specificity enzymes with a lipid kinase activity which phosphorylates phosphoinositides at the 3-hydroxyl, and a protein kinase activity. The products of PI3K-catalysed reactions, phosphatidylinositol 3,4,5-trisphosphate (PtdIns(3,4,5)P3), PtdIns(3,4)P2 and PtdIns(3)P, are second messengers in a variety of signal transduction pathways, including those essential to cell proliferation, adhesion, survival, cytoskeletal rearrangement and vesicle trafficking. Here we report the 2.2 A X-ray crystallographic structure of the catalytic subunit of PI3Kgamma, the class I enzyme that is activated by heterotrimeric G-protein betagamma subunits and Ras. PI3Kgamma has a modular organization centred around a helical-domain spine, with C2 and catalytic domains positioned to interact with phospholipid membranes, and a Ras-binding domain placed against the catalytic domain where it could drive allosteric activation of the enzyme.
authors.affiliation: MRC Laboratory of Molecular Biology, MRC Centre, Cambridge, UK.
authors.forename: E H
authors.initials: EH
authors.lastname: Walker
authors.forename: O
authors.initials: O
authors.lastname: Perisic
authors.forename: C
authors.initials: C
authors.lastname: Ried
authors.forename: L
authors.initials: L
authors.lastname: Stephens
authors.forename: R L
authors.initials: RL
authors.lastname: Williams
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D002384:Catalysis; D020134:Catalytic Domain; D002462:Cell Membrane / Q000378:metabolism; D018360:Crystallography, X-Ray; D006801:Humans; D008958:Models, Molecular; D008969:Molecular Sequence Data; D019869:Phosphatidylinositol 3-Kinases / Q000737:chemistry* / Q000378:metabolism; D011485:Protein Binding; D011487:Protein Conformation; D017434:Protein Structure, Tertiary; D011994:Recombinant Proteins; D017386:Sequence Homology, Amino Acid; D015398:Signal Transduction; D013552:Swine; D020827:rap1 GTP-Binding Proteins / Q000378:metabolism; D018631:ras Proteins / Q000378:metabolism
chemical_list: D011994:Recombinant Proteins; D019869:Phosphatidylinositol 3-Kinases; D020827:rap1 GTP-Binding Proteins; D018631:ras Proteins