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) and possibly T-type (CACNA1G). 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 (Probable). Colocalizes with CACNA1A in lipid raft fractions. Predominantly expressed in brain in a restricted pattern. Also expressed at lower level in kidney and testis Not expressed in lung at any moment of development. In brain, it localizes to sections of P21 brain. Expressed at high level in the cerebellum, with moderate levels in medulla, pons, and striatum. Also expressed in cortex, hippocampus, habenula and nucleus reticularis thalami (nRT). Strongly expressed in cerebellar Purkinje cells. 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-2-2 and delta-2 that are disulfide-linked. It is however unclear whether such cleavage really takes place in vivo and has a functional role. According to PubMed:11306709, it is processed, at least in vitro, while according to PubMed:17052222, it is only poorly processed in vivo. Defects in Cacna2d2 are the cause of ducky phenotype (du). Du mice have spike-wave seizures characteristic of absence epilepsy and ataxia, with accompanying decreased calcium channel current in cerebellar Purkinje cells. Mice exhibit growth retardation, reduced life span, ataxic gait with apoptosis of cerebellar granule cells followed by Purkinje cell depletion, enhanced susceptibility to seizures, and cardiac abnormalities. Binds gabapentin, an antiepileptic drug. Belongs to the calcium channel subunit alpha-2/delta family.