Regulation of D-myo-inositol 1,4,5-trisphosphate 3-kinase by cAMP-dependent protein kinase and protein kinase C.

摘要: The Ca2(+)-mobilizing second messenger D-myo-inositol 1,4,5-trisphosphate (Ins(1,4,5)P3) is converted to the putative 1,3,4,5-tetrakisphosphate by Ins(1,4,5)P3 3-kinase. We found that cAMP-dependent protein kinase and C phosphorylate, thereby modulate, activity of introduced a stoichiometric amount phosphate at serine 109 53-kDa polypeptide caused 1.8-fold increase in Vmax, whereas C-dependent phosphorylation reduced Vmax one-fourth unphosphorylated enzyme. Upon prolonged incubation, multiple sites 3-kinase, resulting inactivation enzyme appeared be well-correlated with simultaneous two major sites, 175. Km for was not affected significantly after either kinase. propose, therefore, 3-kinase constitutes mechanisms cross-talk between cellular signaling pathways use various messengers such as inositol phosphates, diacylglycerol, Ca2+, cAMP.