[Studies of phosphorylation in rat mast cells (second report)--phosphatidylinositol kinase in rat mast cell granule membranes].
Granules were isolated from sonicated purified rat mast cells on a Percoll gradient. The granules were shown to contain a highly active phosphatidylinositol kinase which catalyzes the formation of diphosphoinositide (DPI) from endogenous phosphatidylinositol in the granule membrane. The enzyme requires ATP and Mg2+ or Mn2+ for activity. DPI formation is almost completely dependent on MgCl2 or MnCl2, and maximal response was observed at 20 mM or 2 mM, respectively. The effects of the divalent cations are competitive. Ca2+, fluoride and cyclic AMP are inhibitory. The Km for ATP is 25 microM. The initial reaction is rapid, but the response ceases within a few min. The maximal response is seen at 28 degrees C.
D019870:1-Phosphatidylinositol 4-Kinase; D000255:Adenosine Triphosphate / Q000494:pharmacology; D000818:Animals; D002413:Cations, Divalent / Q000494:pharmacology; D002458:Cell Fractionation / Q000379:methods; D000242:Cyclic AMP / Q000494:pharmacology; D006152:Cyclic GMP / Q000494:pharmacology; D003594:Cytoplasmic Granules / Q000201:enzymology; D005459:Fluorides / Q000494:pharmacology; D066298:In Vitro Techniques; D008297:Male; D008407:Mast Cells / Q000378:metabolism*; D018129:Phosphatidylinositol Phosphates; D010716:Phosphatidylinositols / Q000096:biosynthesis*; D010770:Phosphotransferases / Q000378:metabolism*; D051381:Rats; D011919:Rats, Inbred Strains
D002413:Cations, Divalent; D018129:Phosphatidylinositol Phosphates; D010716:Phosphatidylinositols; C023687:diphosphoinositides; D000255:Adenosine Triphosphate; D000242:Cyclic AMP; D010770:Phosphotransferases; D019870:1-Phosphatidylinositol 4-Kinase; D006152:Cyclic GMP; D005459:Fluorides