Phosphatidylinositol kinase and phosphatidylinositol 4-phosphate kinase activities in Md 66 insect cell line.

Abstract

Phosphatidylinositol kinase (PI kinase) and phosphatidylinositol 4-phosphate kinase (PIP kinase) activities in an insect cell line (Md 66) were studied by measuring the incorporation of 32P from [gamma-32P] ATP into phosphatidylinositol 4-phosphate (PIP) and phosphatidylinositol 4,5-bisphosphate (PIP2) respectively. The apparent Km values of phosphatidylinositol kinase and phosphatidylinositol 4-phosphate kinase for ATP were 78.5 microM and 71.7 microM respectively. PIP kinase activity was enhanced by GTP analogue guanosine 5-O(thio)triphosphate (GTP gamma S).