Ca2+/calmodulin-sensitive inositol 1,4,5-trisphosphate 3-kinase in rat and bovine brain tissues.
Inositol 1,4,5-trisphosphate (Ins P3) 3-kinase catalyzes the ATP-dependent phosphorylation of Ins P3 to Inositol 1,3,4,5-tetrakisphosphate (Ins P4). Ca2+/calmodulin (CaM)-sensitivity of Ins P3 3-kinase was measured in the crude soluble fraction from rat brain and different anatomic regions of bovine brain. Kinase activity was inhibited in the presence of EGTA (free Ca2+ below 1 nM) as compared to Ca2+ (10 microM free Ca2+) or Ca2+ (10 microM free Ca2+) and CaM (1 microM). Ca2+-sensitivity was also seen for the cAMP phosphodiesterase measured under the same assay conditions, but was not for the Ins P3 5-phosphatase. DEAE-cellulose chromatography of the soluble fraction of rat brain or bovine cerebellum resolved a Ca2+/CaM-sensitive Ins P3 3-kinase (maximal stimulation at 1 microM Ins P3 substrate level was 2.0-3.0 fold).
Takazawa
K
K
Institut de Recherche Interdisciplinaire (IRIBHN), Université Libre de Bruxelles, Belgium.
Passareiro
H
H
Dumont
J E
JE
Erneux
C
C
D015105:3',5'-Cyclic-AMP Phosphodiesterases / Q000378:metabolism; D000818:Animals; D001921:Brain / Q000201:enzymology*; D002118:Calcium / Q000502:physiology*; D002147:Calmodulin / Q000502:physiology*; D002417:Cattle; D002531:Cerebellum / Q000201:enzymology; D004789:Enzyme Activation; D000072181:Inositol Polyphosphate 5-Phosphatases; D010744:Phosphoric Monoester Hydrolases / Q000378:metabolism; D010770:Phosphotransferases / Q000378:metabolism*; D017853:Phosphotransferases (Alcohol Group Acceptor); D051381:Rats
D002147:Calmodulin; D010770:Phosphotransferases; D017853:Phosphotransferases (Alcohol Group Acceptor); C051038:Inositol 1,4,5-trisphosphate 3-kinase; D010744:Phosphoric Monoester Hydrolases; D000072181:Inositol Polyphosphate 5-Phosphatases; D015105:3',5'-Cyclic-AMP Phosphodiesterases; D002118:Calcium