T-type calcium channel subunit alpha-1I (CaV3.3)

The **T-type calcium channel subunit alpha-1I** (CaV3.3, gene symbol *CACNA1I*) is a member of the T-type/low-voltage gated calcium channel family predominantly expressed in the brain and central nervous system[1][3][7]. CaV3.3 channels mediate a transient, low-threshold calcium current essential for neuronal excitability, pacemaker activity, and oscillatory firing patterns[3][4][7]. They are structurally characterized by a unique long, bended S6 helix in domain III, which is important for their gating at low voltages[1][3]. Genetic and functional changes in CaV3.3 have been implicated in epilepsy, psychiatric and sleep disorders, pain, and some cardiovascular pathologies[4]. Several drugs—including mibefradil, otilonium bromide, and pimozide—target T-type channels, although most compounds are non-selective for subtypes[3][4]. Safety concerns are related to off-target actions due to the widespread expression and functions of T-type channels in multiple tissues[4].

Other names

CaV3.3CACNA1IVoltage-dependent T-type calcium channel subunit alpha-1ICav3.3 channel

Blockade of calcium influx through low-voltage activated T-type channels, leading to stabilization of membrane potential and reduced neuronal/smooth muscle excitability Inhibition of rhythmic firing and pacemaker currents