Calcium Channel, Voltage Dependent, L-Type, Alpha 1S Subunit (CACNa1S)

CACNa1S encodes one of the five subunits of the slowly inactivating L-type voltage-dependent calcium channel in skeletal muscle cells. Mutations in this gene have been associated with hypokalemic periodic paralysis, thyrotoxic periodic paralysis and malignant hyperthermia susceptibility. Cav1.1 is a voltage-dependent calcium channel found in the transverse tubule of muscles. In skeletal muscle it associates with the ryanodine receptor RyR1 of the sarcoplasmic reticulum via a mechanical linkage. It senses the voltage change caused by the end-plate potential from nervous stimulation and propagated by sodium channels as action potentials to the T-tubules. When the muscle depolarises, the channel opens to allow calcium entry, as well as activating RyR1 which mediates much greater calcium entry from the sarcoplasmic reticulum.