the enzyme is cleaved at the Asp-Pro clusters, residues 610, 617, and 765, at low pH and different temperatures producing 7 enzyme fragments of 17.4-82.3 kDa of the full-length enzyme of about 100 kDa, overview
phosphorylation of Thr-311 by CaM kinase II results in 8-10fold enzyme activation in the presence of 0.01 mM free Ca2+ and 0.002 mM calmodulin and in a 25fold increase in sensitivity to the Ca2+/calmodulin complex
phosphorylation of enzyme by calmodulin kinase II and protein kinase C added together results in a maximal 60-70fold activation, distinct sites are phosphorylated independently by both protein kinases, prevented by the CaM kinase II inhibitors KN-93, KN-62 and the protein kinase C inhibitor calphostin C
phosphorylation has a regulatory function, protein kinase C inactivates the enzyme by phosphorylating the enzyme at a serine residue, cAMP-dependent protein kinase activates the enzyme by phosphorylating at a serine residue, Ca2+/CaM-dependent kinase II activates the enzyme by phosphorylation of Thr311
isoforms A and B are differentially regulated via phosphorylation by protein kinase C and the cAMP-dependent protein kinase, potential phosphorylation sites
phosphorylation of enzyme by calmodulin kinase II and protein kinase C added together results in a maximal 60-70fold activation, distinct sites are phosphorylated independently by both protein kinases, prevented by the CaM kinase II inhibitors KN-93, KN-62 and the protein kinase C inhibitor calphostin C
phosphorylation has a regulatory function, protein kinase C inactivates the enzyme by phosphorylating the enzyme at Ser175, cAMP-dependent protein kinase activates the enzyme by phosphorylating Ser109, simultaneous phosphorylation at Ser109 and Ser175 also inactivates the enzyme, Ca2+/CaM-dependent kinase II activates the enzyme by phosphorylation of a Thr residue
isoform inositol 1,4,5-trisphosphate 3-kinase A is phosphorylated at residue Ser119 by protein kinase A, leading to a significant reduction of microtubule binding affinity
phosphorylation has a regulatory function, protein kinase C inactivates the enzyme by phosphorylating the enzyme at a Ser residue, cAMP-dependent protein kinase activates the enzyme by phosphorylating a Ser residue, Ca2+/CaM-dependent kinase II activates the enzyme by phosphorylation of a Thr residue
Itpka undergoes proteolysis in intact cells, leading to the accumulation of a stable C-terminal domain of 83 kDa to the endoplasmic reticulum, incubation of Itpka at 37°C for 30 min totally destroys Ins(1,4,5)P3 3-kinase activity unless the enzyme is mixed with 0.1% SDS
2.7.1.127 inositol-trisphosphate 3-kinase
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