Analysis of the catalytic domain of phosphatidylinositol 4-kinase type II.
Phosphatidylinositol (PtdIns) 4-kinases catalyze the conversion of PtdIns to PtdIns 4-phosphate, the major precursor of phosphoinositides that regulates a vast array of cellular processes. Based on enzymatic differences, two classes of PtdIns 4-kinase have been distinguished termed Types II and III. Type III kinases, which belong to the phosphatidylinositol (PI) 3/4-kinase family, have been extensively characterized. In contrast, little is known about the Type II enzymes (PI4KIIs), which have been cloned and sequenced very recently. PI4KIIs bear essentially no sequence similarity to other protein or lipid kinases; hence, they represent a novel and distinct branch of the kinase superfamily. Here we define the minimal catalytic domain of a rat PI4KII isoform, PI4KIIalpha, and identify conserved amino acid residues required for catalysis. We further show that the catalytic domain by itself determines targeting of the kinase to membrane rafts. To verify that the PI4KII family extends beyond mammalian sources, we expressed and characterized Drosophila PI4KII and its catalytic domain. Depletion of PI4KII from Drosophila cells resulted in a severe reduction of PtdIns 4-kinase activity, suggesting the in vivo importance of this enzyme.
Barylko
Barbara
B
Department of Pharmacology, University of Texas Southwestern Medical Center, Dallas 75390, USA.
Wlodarski
Pawel
P
Binns
Derk D
DD
Gerber
Stefan H
SH
Earnest
Svetlana
S
Sudhof
Thomas C
TC
Grichine
Nikolai
N
Albanesi
Joseph P
JP
D019870:1-Phosphatidylinositol 4-Kinase / Q000737:chemistry*; D000199:Actins / Q000378:metabolism; D000595:Amino Acid Sequence; D000730:Androstadienes / Q000494:pharmacology; D000818:Animals; D002384:Catalysis; D020134:Catalytic Domain; D002460:Cell Line; D002462:Cell Membrane; D003001:Cloning, Molecular; D004305:Dose-Response Relationship, Drug; D004330:Drosophila; D004791:Enzyme Inhibitors / Q000494:pharmacology; D006801:Humans; D007313:Insecta; D050356:Lipid Metabolism; D008958:Models, Molecular; D008969:Molecular Sequence Data; D009154:Mutation; D017354:Point Mutation; D011485:Protein Binding; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary; D051381:Rats; D017386:Sequence Homology, Amino Acid; D013997:Time Factors; D000077191:Wortmannin
D000199:Actins; D000730:Androstadienes; D004791:Enzyme Inhibitors; D019870:1-Phosphatidylinositol 4-Kinase; D000077191:Wortmannin