T-type calcium channel

T-type calcium channels are a type of voltage-gated calcium channel that are characterized by their low voltage activation and transient, or 'T'-type, current. They are found in a variety of tissues, including the heart, brain, and smooth muscle.

Structure

T-type calcium channels are composed of a main α1 subunit, which forms the pore through which calcium ions pass, and several auxiliary subunits. The α1 subunit is encoded by three different genes, CACNA1G, CACNA1H, and CACNA1I, which give rise to the Cav3.1, Cav3.2, and Cav3.3 channels, respectively.

Function

T-type calcium channels play a crucial role in shaping the electrical activity of many different cell types. In the heart, they contribute to the pacemaker activity of the sinoatrial node and the conduction of electrical signals through the atrioventricular node. In the brain, they are involved in the generation of burst firing, a type of neuronal firing pattern that is associated with certain types of neurotransmitter release. In smooth muscle, they contribute to the regulation of muscle contraction.

Clinical significance

Mutations in the genes encoding T-type calcium channels have been linked to a variety of disorders. For example, mutations in CACNA1H have been associated with childhood absence epilepsy and idiopathic generalized epilepsy. Mutations in CACNA1G have been linked to spinocerebellar ataxia type 42. In addition, T-type calcium channels have been implicated in the pathophysiology of pain, hypertension, and cancer, and they are being explored as potential therapeutic targets in these conditions.

See also

• Voltage-gated calcium channel
• Calcium channel blocker
• Calcium signaling