Voltage-dependent L-type calcium channel
| Voltage-dependent L-type calcium channel, α1 subunit | ||
|---|---|---|
| Properties of human protein | ||
| Mass / length primary structure | 1873 amino acids (α1) | |
| Secondary to quaternary structure | α1 + α2 + β + δ; multipass membrane protein | |
| Identifier | ||
| Gene names | CACNA1S ; CACH1; DHPR | |
| External IDs | ||
| Transporter classification | ||
| TCDB | 1.A.1.11 | |
| designation | voltage gated ion channel | |
| Occurrence | ||
| Homology family | Calcium transport | |
| Parent taxon | Chordates | |
The voltage-dependent L-type calcium channel (also: dihydropyridine receptor ) is a calcium channel in the cell membrane of the transverse system ( T tubules ) of muscle cells . In cardiac muscle cells, however, they also occur on the surface membrane (calcium-induced calcium release). Homologues can be found in many chordates . The α1 subunit (CACNA1S) of the protein is controlled by the other subunits, but it also functions on its own. Mutations in the CACNA1S gene can lead to periodic paralysis or malignant hyperthermia .
The L-type calcium channel is a voltage-controlled ion channel that activates the ryanodine receptor in the sarcoplasmic reticulum when the cell membrane is depolarized , which leads to an influx of Ca 2+ ions into the cytosol of the muscle cell. This activation takes place in the skeletal muscle through protein-protein interactions of the two receptors / channels, while an influx of calcium from the extracellular area only plays a subordinate role. This activity is regulated by the cytoplasmic concentrations of magnesium, calcium, ATP and calmodulin (CaM), as well as protein kinase A (PKA) and calmodulin kinase. In contrast, the ryanodine receptor in the heart muscle is opened by calcium that has flowed into the cell via the dihydropyridine receptor (calcium-induced calcium release, CICR). The L-type calcium channel is thus involved in the electromechanical coupling .
The inactivation of the channel takes place slowly, which is why it is run as a longlasting, L-type or Ca L channel.
The term “receptor” and not “channel” is due to the fact that its function was not yet known when its affinity for 1,4-dihydropyridines (e.g. nifedipine , amlodipine , nitrendipine , nimodipine , felodipine or clevidipine) was established ) that act as antagonists .
literature
- C. Proenza, J. O'Brien, J. Nakai, S. Mukherjee, PD Allen, KG Beam: Identification of a region of RyR1 that participates in allosteric coupling with the alpha (1S) (Ca (V) 1.1) II- III loop. In: J. Biol. Chem. 277 (8), February 2002, pp. 6530-6535. doi: 10.1074 / jbc.M106471200 . PMID 11726651 .
- K. Jurkat-Rott, F. Lehmann-Horn: Muscle channelopathies and critical points in functional and genetic studies. In: J. Clin. Invest. 115 (8), August 2005, pp. 2000-2009. doi: 10.1172 / JCI25525 . PMC 1180551 (free full text). PMID 16075040 .
Individual evidence
- ^ Boron, Walter F., Boulpaep, Emile L.,: Medical physiology . Third ed. Philadelphia, PA 2017, ISBN 978-1-4557-3328-6 .