FIGURE 4.

CaMKII can phosphorylate the full-length InsP₃R2 on Ser-150. Upper panel, CaMKII phosphorylation assays performed using full-length InsP₃R2 expressed in COS-1 cells as substrates show that mutation of Ser-150 → Ala could abolish CaMKII-mediated phosphorylation of full-length InsP₃R2-S150A. Full-length InsP₃R2 not containing the mutation showed significant incorporation of ³²P when treated with CaMKII. Lower panel, Western blotting of the membrane with T2NH antibody confirmed the presence of similar protein amounts within samples used in the phosphorylation reactions.