voltage-dependent Ca+2 channel alpha-1S (voltage-dependent Ca+2 channel-alpha 1 isoform 3 skeletal muscle, L type, CACNA1S, CACNL1A3, CACH1, CACN1,)
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Function
- pore-forming & voltage-sensitive alpha-1 subunit of voltage-sensitive Ca+2 channel
- alpha-1S gives rise to L-type Ca+2 currents
- L-type Ca+2 channels (long-lasting) belong to the 'high-voltage activated' (HVA) group
- blocked by dihydropyridines (DHP), phenylalkylamines, benzothiazepines, & by omega-agatoxin-IIIA (omega-Aga-IIIA)
- insensitive to omega-conotoxin-GVIA (omega-CTx-GVIA) & omega-agatoxin-IVA (omega-Aga-IVA)
- role in excitation-contraction coupling in skeletal muscle
- interacts with DYSF & JSRP1
- phosphorylation by PKA activates the Ca+2 channel
Structure
- each of the 4 internal repeats contains 5 hydrophobic transmembrane segments (S1, S2, S3, S5, S6) & one positively charged transmembrane segment (S4)
- S4 segments probably represent the voltage-sensor & are characterized by a series of positively charged amino acids at every third position
- the loop between repeats II & III interacts with the ryanodine receptor, & is therefore important for Ca+2 release from the endoplasmic reticulum in muscle contraction
- belongs to the Ca+2 channel alpha-1 subunit (TC 1.A.1.11) family
- an additional gamma subunit is present only in skeletal muscle L-type channel
Compartment
membrane
Expression
skeletal muscle specific
Pathology
- mutations in CACNA1S associated with
Laboratory
More general terms
Additional terms
- familial periodic paralysis (hyperkalemic, normokalemic, hypokalemic, HYPP, NKPP, HYPOPP)
- malignant hyperthermia/hyperthermia of anesthesia
- voltage-dependent Ca+2 channel