Both EF-hand and pre-IQ-IQ domains of Ca_v2.1 are required to unmask CDF in Ca_v2.2. (A–D) As in Fig. 5 B except cells transfected with Ca_v2.2 channels containing pre-IQ-IQ and CBD (A), EF-hand and CBD (B), or EF-hand and pre-IQ-IQ (C) of Ca_v2.1 or Ca_v2.2 channels containing EF-hand and pre-IQ-IQ of Ca_v2.1 (D). Data represent mean ± SEM.