CACNA2D1

Alpha-2/delta-1, the founding member of the four-gene mammalian alpha-2/delta family and an auxiliary subunit of high-voltage-activated calcium channels. The single precursor is cleaved and disulphide-linked into an extracellular alpha-2 chain and a membrane-attached delta chain, and the mature protein is tethered to the outer face of the plasma membrane through a GPI anchor; its extracellular region carries VWA (with a MIDAS motif) and Cache domains. Assembled with a pore-forming CaV1 or CaV2 alpha-1 subunit and a cytoplasmic CaV-beta subunit, it raises calcium-current density and shifts voltage-dependent activation to more negative potentials, largely by increasing the number of channels at the cell surface rather than by conducting ions itself. It is expressed in skeletal and cardiac muscle T-tubules, in vascular smooth muscle, and broadly in neurons, where it concentrates at presynaptic terminals. It is the high-affinity binding site for the gabapentinoid drugs gabapentin and pregabalin. Biallelic loss-of-function variants cause an early-onset developmental and epileptic encephalopathy, and missense variants have been associated with short-QT and Brugada-like cardiac syndromes. Two further roles are proposed and contested. The first is that alpha-2/delta-1 is the neuronal thrombospondin receptor that drives excitatory synaptogenesis; a conditional triple knockout of presynaptic alpha-2/delta-1, -2 and -3 found synapse development, active-zone ultrastructure and transsynaptic alignment intact and reassigned presynaptic alpha-2/delta to setting synaptic gain through Munc13-1, while astrocyte-conditioned-medium experiments continue to support a postsynaptic thrombospondin-1 receptor role. The second is that alpha-2/delta-1 forms a gabapentin-sensitive complex with NMDA receptors, independently of calcium channels, and promotes their synaptic trafficking in chronic pain; this model rests almost entirely on work from a single laboratory and has not been independently replicated.

Disorders

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• cardiac_ion_channel_repolarization via Short QT Syndrome