Ca2+/calmodulin independent inositol 1,4,5-trisphosphate 3-kinase activity in guinea pig peritoneal macrophages.
1. The Ca2+/calmodulin (CaM) independent activity of inositol 1,4,5-trisphosphate (InsP3) 3-kinase in macrophages could be separated from the dependent activity by serial column chromatography, gel filtration, Orange A and DEAE-5PW. 2. An InsP3 analog which has an aminobenzoyl group on the 2nd carbon of the inositol ring inhibited the conversion of [3H]InsP3 to [3H]InsP4 (inositol 1,3,4,5-tetrakisphosphate) in a dose-dependent manner. The concentration required for half-maximal inhibition (IC50) with the Ca2+/CaM independent enzyme activity was also dependent on the free Ca2+ concentration, as with the dependent activity. 3. These results suggest that a conformational change in the enzyme occurs in response to a change in free Ca2+ concentration, and thus the potency to recognize the InsP3 analog would change, even when the Ca2+/CaM independent enzyme activity was used.
Kimura
Y
Y
Department of Biochemistry, Faculty of Dentistry, Kyushu University, Fukuoka, Japan.
Watanabe
Y
Y
Ozaki
S
S
Koga
T
T
Hirata
M
M
D000818:Animals; D002118:Calcium / Q000378:metabolism; D002147:Calmodulin / Q000378:metabolism; D006168:Guinea Pigs; D007295:Inositol Phosphates / Q000494:pharmacology; D008264:Macrophages / Q000378:metabolism*; D010529:Peritoneal Cavity / Q000166:cytology; D010770:Phosphotransferases / Q000037:antagonists & inhibitors / Q000378:metabolism*; D017853:Phosphotransferases (Alcohol Group Acceptor)
D002147:Calmodulin; D007295:Inositol Phosphates; D010770:Phosphotransferases; D017853:Phosphotransferases (Alcohol Group Acceptor); C051038:Inositol 1,4,5-trisphosphate 3-kinase; D002118:Calcium