Voltage gated calcium channels control cellular calcium entry in response to changes in membrane potential. The isoleucine-glutamine (IQ) motif in the voltage gated calcium channel IQ domain interacts with hydrophobic pockets of Ca2+/calmodulin [1]. The interaction regulates two self-regulatory calcium dependent feedback mechanism, calcium dependent inactivation (CDI), and calcium-dependent facilitation (CDF).

1: Insights into voltage-gated calcium channel regulation from the structure of the CaV1.2 IQ domain-Ca2+/calmodulin complex. Van Petegem F, Chatelain FC, Minor DL Jr; Nat Struct Mol Biol. 2005;12:1108-1115. PMID:16299511