title: Stimulation of purified phosphatidylinositol 4-kinase by cobra venom cardiotoxin.
abstract: Cobra venom cardiotoxin was found to stimulate the phosphatidylinositol kinase activity present in A431 cell membranes and in detergent extracts of these membranes. Incubation of highly purified phosphatidylinositol 4-kinase from this source with cardiotoxin resulted in a 2- to 3-fold stimulation of phosphatidylinositol kinase activity. The activation of the purified phosphatidylinositol 4-kinase by cardiotoxin was time- and dose-dependent and appeared to be associated with a decrease in the Km apparent of the enzyme for phosphatidylinositol with no change in the Vmax apparent of the enzyme. The data suggest that the phosphatidylinositol 4-kinase is activated by direct interaction of the enzyme with cobra venom cardiotoxin.
authors.affiliation: Howard Hughes Medical Institute, Washington University School of Medicine, St. Louis, MO 63110.
authors.forename: D H
authors.initials: DH
authors.lastname: Walker
authors.forename: L J
authors.initials: LJ
authors.lastname: Pike
mesh_terms: D019870:1-Phosphatidylinositol 4-Kinase; D002462:Cell Membrane / Q000201:enzymology; D004179:Cobra Cardiotoxin Proteins / Q000494:pharmacology*; D004789:Enzyme Activation; D007700:Kinetics; D010770:Phosphotransferases / Q000187:drug effects / Q000378:metabolism*; D011073:Polyamines / Q000494:pharmacology
chemical_list: D004179:Cobra Cardiotoxin Proteins; D011073:Polyamines; D010770:Phosphotransferases; D019870:1-Phosphatidylinositol 4-Kinase