Fig. 1.
CaMKIIδ phosphorylates RyR2 at Ser2814 in response to increased heart rate. (A) RyR2 immunoprecipitated from hearts from WT, RyR2-S2814A knock-in mice, and WT samples treated with either 1 μM KN-93 or PKI incubated with CaMKIIδ or PKA in the presence of [γ32P]-ATP. (B) Lysates of low- and high-frequency paced WT, RyR2-S2814A, RyR2-S2808A, and KN-93–treated WT hearts. Blots show total CaMKIIδ, activated CaMKIIδ (pThr287), and total PLN levels. The phosphorylation status of PLN at Ser16 and Thr17 are also shown. (C) RyR2 immunoprecipitated from baseline and high-frequency paced hearts. Blot shows phosphorylation status of RyR2-Ser2808 and RyR2-Ser2814, as well as the levels of CaMKIIδ and activated CaMKIIδ complexed with RyR2. (D–G) Quantitative summary of data (‡P < 0.05 vs. WT; *P < 0.05 vs. baseline). All experiments were performed in triplicate. AU, arbitrary unit.