Type I phosphatidylinositol 4-phosphate 5-kinase isoforms are specifically stimulated by phosphatidic acid.
A phosphatidylinositol 4-phosphate (PIP) kinase was isolated and purified to near homogeneity from bovine erythrocyte membranes. The PIP kinase was extracted from bovine erythrocyte membranes with a high salt wash, followed by phosphocellulose and phenyl-Sepharose chromatography. The predominant protein after phenyl-Sepharose purification had a molecular size of 68 kDa. Renaturation of PIP kinase activity after SDS-PAGE showed that a 68-kDa protein was able to phosphorylate PIP. An antibody developed against the 68-kDa protein Western blots the 68-kDa protein and is able to immunoprecipitate the 68-kDa protein and PIP kinase activity from membrane extracts. Based on functional studies, the 68-kDa protein is indistinguishable from the type I PIP kinase previously characterized from human erythrocyte membranes (Bazenet, C. E., Ruano, A.R., Brockman, J.L., and Anderson, R.A. (1990) J. Biol. Chem. 265, 18012-18022). These studies also show that the type I PIP kinases, but not the type II PIP kinase, are stimulated by phosphatidic acid, suggesting alternative roles for these enzymes. Two immunoreactive isoforms of the type I PIP kinase, of 68 and 90 kDa, were identified in rat brain and partially purified. Both of these isoforms are also stimulated by phosphatidic acid.
Jenkins
G H
GH
Department of Pharmacology, University of Wisconsin Medical School, Madison 53706.
Fisette
P L
PL
Anderson
R A
RA
D000818:Animals; D015153:Blotting, Western; D002417:Cattle; D002852:Chromatography, Ion Exchange; D004591:Electrophoresis, Polyacrylamide Gel; D004910:Erythrocyte Membrane / Q000201:enzymology*; D007527:Isoenzymes / Q000097:blood* / Q000737:chemistry / Q000302:isolation & purification; D007700:Kinetics; D008970:Molecular Weight; D010712:Phosphatidic Acids / Q000494:pharmacology*; D010743:Phospholipids / Q000494:pharmacology; D017853:Phosphotransferases (Alcohol Group Acceptor) / Q000097:blood* / Q000737:chemistry / Q000302:isolation & purification; D011489:Protein Denaturation; D017510:Protein Folding
D007527:Isoenzymes; D010712:Phosphatidic Acids; D010743:Phospholipids; D017853:Phosphotransferases (Alcohol Group Acceptor); C020077:1-phosphatidylinositol-4-phosphate 5-kinase