title: A phosphatidylinositol kinase in rat mast cell granules.
abstract: Intact granules were isolated from sonicated purified rat serosal mast cells on a Percoll gradient. The granules were shown to contain a highly active phosphatidylinositol kinase that catalyzes the formation of diphosphoinositide from endogenous phosphatidylinositol in the granule membrane. The enzyme requires ATP and Mg2+ or Mn2+ for activity; 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 minutes. A comparison of the rate of phosphorylation of intact and broken membrane granules suggests that the phosphorylation occurs on the outer (cytoplasmic) surface of the granules.
mesh_terms: D019870:1-Phosphatidylinositol 4-Kinase; D000255:Adenosine Triphosphate / Q000502:physiology; D000818:Animals; D002712:Chlorides; D000242:Cyclic AMP / Q000494:pharmacology; D003594:Cytoplasmic Granules / Q000201:enzymology* / Q000378:metabolism; D007425:Intracellular Membranes / Q000201:enzymology; D007700:Kinetics; D008274:Magnesium / Q000494:pharmacology; D015636:Magnesium Chloride; D008297:Male; D008345:Manganese / Q000494:pharmacology; D017895:Manganese Compounds; D008407:Mast Cells / Q000201:enzymology* / Q000378:metabolism; D018129:Phosphatidylinositol Phosphates; D010716:Phosphatidylinositols / Q000096:biosynthesis; D010770:Phosphotransferases / Q000378:metabolism*; D051381:Rats; D011919:Rats, Inbred Strains; D012969:Sodium Fluoride / Q000494:pharmacology; D013696:Temperature
chemical_list: D002712:Chlorides; D017895:Manganese Compounds; D018129:Phosphatidylinositol Phosphates; D010716:Phosphatidylinositols; C037178:phosphatidylinositol 4-phosphate; D015636:Magnesium Chloride; D008345:Manganese; D000255:Adenosine Triphosphate; D012969:Sodium Fluoride; D000242:Cyclic AMP; D010770:Phosphotransferases; D019870:1-Phosphatidylinositol 4-Kinase; D008274:Magnesium; C025340:manganese chloride