Ca2+ dependence of inositol 1,4,5-trisphosphate 3-kinase activity in the cytosol fraction of pig coronary artery.
1. The activity of inositol 1,4,5-trisphosphate 3-kinase in subcellular fractions of smooth muscles of the pig coronary artery was examined. 2. Incubation of [3H]inositol 1,4,5-trisphosphate (IP3) with muscle homogenates produced more polar 3H-radioactivity (probably as inositol 1,3,4,5-tetrakisphosphate, IP4) than IP3, in the Mg2+- and ATP-dependent manner, thereby indicating the presence of IP3 3-kinase activity in homogenates of the muscle. 3. Most of the kinase activity was present in the cytosol fraction. The enzyme activity was reversibly activated by Ca2+ with a half-maximal effective concentration of 2.5 x 10(-7) M. 4. The calmodulin antagonists, W-7 and chlorpromazine inhibited the Ca2+-activated enzyme activity.
Yamaguchi
K
K
Department of Pharmacology, Faculty of Medicine, Kyushu University, Fukuoka, Japan.
Hirata
M
M
Ishimatsu
T
T
Kuriyama
H
H
D000818:Animals; D002118:Calcium / Q000494:pharmacology*; D002147:Calmodulin / Q000037:antagonists & inhibitors; D002746:Chlorpromazine / Q000494:pharmacology; D002851:Chromatography, High Pressure Liquid; D003326:Coronary Circulation / Q000187:drug effects*; D003600:Cytosol / Q000201:enzymology*; D009131:Muscle, Smooth, Vascular / Q000187:drug effects*; D010770:Phosphotransferases / Q000037:antagonists & inhibitors / Q000378:metabolism*; D017853:Phosphotransferases (Alcohol Group Acceptor); D013449:Sulfonamides / Q000494:pharmacology; D013552:Swine
D002147:Calmodulin; D013449:Sulfonamides; C017967:W 7; D010770:Phosphotransferases; D017853:Phosphotransferases (Alcohol Group Acceptor); C051038:Inositol 1,4,5-trisphosphate 3-kinase; D002118:Calcium; D002746:Chlorpromazine