CALM1 and catecholaminergic polymorphic ventricular tachycardia: To determine the effect of CPVT-associated mutations on the structure of Ca2+/CaM–RyR23583-3603 complexes, we compared Ca2+/CaM-WT–RyR23583-3603 with Ca2+/CaM-N53I–RyR23583-3603 and Ca2+/CaM-A102V–RyR23583-3603 peptide complex crystal structures obtained in this study (Fig. 3D,E).