title: Molecular cloning and biochemical characterization of a Drosophila phosphatidylinositol-specific phosphoinositide 3-kinase.
abstract: Molecular, biochemical and genetic characterization of phosphoinositide 3-kinases (PI3Ks) have identified distinct classes of enzymes involved in processes mediated by activation of cell-surface receptors and in constitutive intracellular protein trafficking events. The latter process appears to involve a PtdIns-specific PI3K first described in yeast as a mutant, vps34, defective in the sorting of newly synthesized proteins from the Golgi to the vacuole. We have identified a representative member of each class of PI3Ks in Drosophila using a PCR-based approach. In the present paper we describe the molecular cloning of a PI3K from Drosophila, P13K_59F, that shows sequence similarity to Vps34. PI3K_59F encodes a protein of 108 kDa co-linear with Vps34 homologues, and with three regions of sequence similarity to other PI3Ks. Biochemical characterization of the enzyme, by expression of the complete coding sequence as a glutathione S-transferase fusion protein in Sf9 cells, demonstrates that PI3K_59F is a PtdIns-specific PI3K that can utilize either Mg2+ or Mn2+. This activity is sensitive to inhibition both by non-ionic detergent (Nonidet P40) and by wortmannin (IC50 10 nM). PI3K_59F, therefore, conserves both the structural and biochemical properties of the Vps34 class of enzymes.
authors.affiliation: Ludwig Institute for Cancer Research, University College London, U.K.
authors.forename: C
authors.initials: C
authors.lastname: Linassier
authors.forename: L K
authors.initials: LK
authors.lastname: MacDougall
authors.forename: J
authors.initials: J
authors.lastname: Domin
authors.forename: M D
authors.initials: MD
authors.lastname: Waterfield
mesh_terms: D000595:Amino Acid Sequence; D000730:Androstadienes / Q000494:pharmacology; D000818:Animals; D001483:Base Sequence; D002851:Chromatography, High Pressure Liquid; D002855:Chromatography, Thin Layer; D003001:Cloning, Molecular; D017931:DNA Primers; D004330:Drosophila; D008055:Lipids / Q000032:analysis; D008969:Molecular Sequence Data; D019869:Phosphatidylinositol 3-Kinases; D010716:Phosphatidylinositols / Q000378:metabolism*; D017853:Phosphotransferases (Alcohol Group Acceptor) / Q000737:chemistry*; D011993:Recombinant Fusion Proteins / Q000235:genetics; D017421:Sequence Analysis; D013379:Substrate Specificity; D000077191:Wortmannin
chemical_list: D000730:Androstadienes; D017931:DNA Primers; D008055:Lipids; D010716:Phosphatidylinositols; D011993:Recombinant Fusion Proteins; D019869:Phosphatidylinositol 3-Kinases; D017853:Phosphotransferases (Alcohol Group Acceptor); D000077191:Wortmannin