The contribution of serine residues 1588 and 1755 to phosphorylation of the type I inositol 1,4,5-trisphosphate receptor by PKA and PKG

Type I inositol 1,4,5-trisphosphate receptors can be phosphorylated by cAMP-dependent protein kinase (PKA) and cGMP-dependent protein kinase (PKG). To define the site-specificity of these events we analyzed the phosphorylation of mutant receptors expressed in intact cells. These studies showed that S-1588 and S-1755, the serine residues within kinase consensus sequences, are equally sensitive to PKA, that phosphorylation events at these sites are independent of each other, and that PKG predominantly phosphorylates S-1588. These findings provide the basis for understanding the functional consequences of type I inositol 1,4,5-trisphosphate receptor phosphorylation. (C) 2003 Published by Elsevier B.V. on behalf of the Federation of European Biochemical Societies.