title: Evidence that phosphorylase kinase exhibits phosphatidylinositol kinase activity.
abstract: Phosphorylase kinase phosphorylates the pure phospholipid phosphatidylinositol. Furthermore, it catalyzed phosphatidylinositol 4-phosphate formation using as substrate phosphatidylinositol that is associated with an isolated trypsin-treated Ca2+-transport adenosinetriphosphatase (ATPase) preparation from skeletal muscle sarcoplasmic reticulum. On this basis a fast and easy assay was developed that allows one to follow the phosphatidylinositol kinase activity during a standard phosphorylase kinase preparation. Both activities are enriched in parallel approximately to the same degree. Neither chromatography on DEAE-cellulose nor that on hydroxyapatite in the presence of 1 M KCl separates phosphatidylinositol kinase from phosphorylase kinase. The presence of a lipid kinase, phosphatidylinositol kinase, in phosphorylase kinase is not a general phenomenon; diacylglycerol kinase can be easily separated from phosphorylase kinase. Polyclonal anti-phosphorylase kinase antibodies as well as a monoclonal antibody directed specifically against the alpha subunit of phosphorylase kinase immunoprecipitate both phosphorylase kinase and phosphatidylinositol kinase.
mesh_terms: D019870:1-Phosphatidylinositol 4-Kinase; D000818:Animals; D000252:Calcium-Transporting ATPases / Q000378:metabolism; D019852:Diacylglycerol Kinase; D007700:Kinetics; D009132:Muscles / Q000201:enzymology; D010764:Phosphorylase Kinase / Q000302:isolation & purification / Q000378:metabolism*; D010763:Phosphorylase b / Q000378:metabolism; D010770:Phosphotransferases / Q000302:isolation & purification / Q000378:metabolism*; D012519:Sarcoplasmic Reticulum / Q000201:enzymology
chemical_list: D010763:Phosphorylase b; D010770:Phosphotransferases; D019852:Diacylglycerol Kinase; D010764:Phosphorylase Kinase; D019870:1-Phosphatidylinositol 4-Kinase; D000252:Calcium-Transporting ATPases