A diphosphoinositide kinase in rat mast cell granules.
Intact granules were isolated from sonicated purified rat serosal mast cells on a Percoll gradient. The granules were demonstrated to contain a diphosphoinositide kinase that catalyzes the formation of triphosphoinositide from diphosphoinositide. The enzyme requires adenosine triphosphate and Mg2+ or Mn2+ for activity. The Km for adenosine triphosphate is 3 mumol/L, and maximal response is observed at 20 mmol/L of Mg2+ or 1 mmol/L of Mn2+, respectively. Triphosphoinositide synthesis in the granules is dependent on the time and temperature of the incubations. Cyclic adenosine monophosphate, adenosine, adenosine diphosphate, and adenosine monophosphate decrease the enzyme activity. 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.
Kurosawa
M
M
Department of Internal Medicine, Gunma University School of Medicine, Maebashi, Japan.
Okayama
Y
Y
Kobayashi
S
S
D000255:Adenosine Triphosphate / Q000502:physiology; D000818:Animals; D002412:Cations / Q000494:pharmacology; D002855:Chromatography, Thin Layer; D003594:Cytoplasmic Granules / Q000201:enzymology; D008407:Mast Cells / Q000201:enzymology*; D019269:Phosphatidylinositol 4,5-Diphosphate; D010716:Phosphatidylinositols / Q000378:metabolism; D010770:Phosphotransferases / Q000378:metabolism*; D017853:Phosphotransferases (Alcohol Group Acceptor); D051381:Rats; D011919:Rats, Inbred Strains; D013696:Temperature
D002412:Cations; D019269:Phosphatidylinositol 4,5-Diphosphate; D010716:Phosphatidylinositols; D000255:Adenosine Triphosphate; D010770:Phosphotransferases; D017853:Phosphotransferases (Alcohol Group Acceptor); C020077:1-phosphatidylinositol-4-phosphate 5-kinase