T-type voltage-sensitive calcium channel (CaV3)

T-type voltage-sensitive calcium channels are low-voltage-activated ion channels that mediate transient (T-type) calcium currents across the plasma membrane of excitable cells. They open at membrane potentials near the resting potential and quickly inactivate, providing short-lived calcium influx. There are three known mammalian isoforms—CaV3.1 (CACNA1G), CaV3.2 (CACNA1H), and CaV3.3 (CACNA1I)—which differ in kinetics, expression profile, and pharmacology[1][3][4]. Structurally, each channel consists of a single α1 subunit with four homologous domains, each containing six transmembrane segments, forming the pore and voltage sensor[1][3][5]. T-type channels play key roles in neuronal rhythmic activity, cardiac pacemaking, hormone secretion, and smooth muscle contraction[1][4][5]. Altered T-type channel activity is implicated in a range of diseases, including epilepsy, pain syndromes, cardiac arrhythmias, and neuropsychiatric disorders, making them important therapeutic targets. Several drugs, both approved and experimental, act by inhibiting or modulating T-type channels, although safety and specificity remain challenges for clinical development[2][4].

Other names

T-type calcium channelLow-voltage activated calcium channelCaV3.1 (CACNA1G)CaV3.2 (CACNA1H)CaV3.3 (CACNA1I)Transient-type calcium channel

Channel blockade to inhibit calcium influx and reduce neuronal excitability (blockers such as mibefradil, TTA-A2) Modulation of channel gating, including blocking open state or allosteric inhibition Channel enhancement to promote calcium entry (e.g., SAK3 for cognitive enhancement) Inhibition reduces burst firing and pacemaker activity (therapeutic in seizure and pain syndromes)