The alpha-2/delta subunit of voltage-dependent calcium channels regulates calcium current density and activation/inactivation kinetics of the calcium channel. Acts as a regulatory subunit for P/Q-type calcium channel (CACNA1A), N-type (CACNA1B), L-type (CACNA1C OR CACNA1D) but not T-type (CACNA1G) (By similarity). Dimer formed of alpha-2-2 and delta-2 chains; disulfide-linked. Voltage-dependent calcium channels are multisubunit complexes, consisting of alpha-1 (CACNA1), alpha-2 (CACNA2D), beta (CACNB) and delta (CACNA2D) subunits in a 1:1:1:1 ratio (By similarity). Only detected in brain. Not present in lung, testis, aorta, spleen, jejunum, ventricular muscle and kidney (at protein level). According to PubMed:11687876, it is brain-specific, while according to PubMed:11245980, it is widely expressed. The MIDAS-like motif in the VWFA domain binds divalent metal cations and is required to promote trafficking of the alpha-1 (CACNA1) subunit to the plasma membrane by an integrin-like switch. N-glycosylated. May be proteolytically processed into subunits alpha-2-3 and delta-3 that are disulfide-linked. It is however unclear whether such cleavage really takes place in vivo and has a functional role (By similarity). In contrast to CACNA2D1 and CACNA2D2, it does not bind gabapentin, an antiepileptic drug. Belongs to the calcium channel subunit alpha-2/delta family.