2VAY77912292ENSG00000081248ENSMUSG00000026407Q13698Q02789NM_000069NM_001081023NM_014193NP_000060NP_001074492NP_055008NP_001389878Cav1.1 also known as the calcium channel, voltage-dependent, L type, alpha 1S subunit, (CACNA1S), is a protein which in humans is encoded by the CACNA1S gene.

This gene encodes one of the five subunits of the slowly inactivating L-type voltage-dependent calcium channel in skeletal muscle cells.

[6] In hypokalemic periodic paralysis (HOKPP), the voltage sensors in domains 2 and 4 of Cav1.1 are mutated (loss-of-function), reducing the availability of the channel to sense depolarisation, and therefore it cannot activate the ryanodine receptor as efficiently.

The condition is hypokalemic because a low extracellular potassium ion concentration will cause the muscle to repolarise to the resting potential more quickly, so any calcium conductance that does occur cannot be sustained.

In contrast, hyperkalemic periodic paralysis refers to gain-of-function mutations in sodium channels that maintain muscle depolarisation and therefore are aggravated by high potassium ion concentrations.