T-type calcium channel alpha-1 subunit (CaV3.x (where x = 1G, 1H, 1I; also CCNA1G, CACNA1H, CACNA1I for gene-based nomenclature))

The T-type calcium channel alpha-1 subunit (CaV3 family) forms the central pore of T-type (transient, low-voltage activated) calcium channels. These channels are distinguished by their ability to open with relatively slight depolarizations near the resting membrane potential and display rapid activation and inactivation kinetics[1][7]. There are three principal gene-encoded variants in humans—CaV3.1 (CACNA1G), CaV3.2 (CACNA1H), and CaV3.3 (CACNA1I)—each with distinct physiological and pharmacological properties[1][7]. The channel’s functions include pacemaking activity in cardiac nodal tissues, setting rhythmic firing in thalamic and other central neurons, and contributing to muscle contraction, hormone release, and cellular excitability[1][4][6]. Pathologically, mutations and altered expression of these channels are implicated in epilepsy and other neuropsychiatric disorders, certain cardiac conditions, and various cancers[2][3][6]. Pharmacological agents targeting these channels—including ethosuximide and mibefradil—act by blocking the calcium influx mediated by these channels, though clinical use is hampered by selectivity and cardiac safety risks[8][4][6].

Other names

Voltage-dependent T-type calcium channel subunit alpha-1G (CaV3.1)Voltage-dependent T-type calcium channel subunit alpha-1H (CaV3.2)Voltage-dependent T-type calcium channel subunit alpha-1I (CaV3.3)CACNA1G (gene)CACNA1H (gene)CACNA1I (gene)T-type calcium channel

Inhibition of calcium influx through blockage of the channel pore, preventing calcium-dependent processes such as action potentials and transmitter release; Reduction of neuronal and cardiac excitability; Modulation of hormone or neurotransmitter release