Ca<sub>V</sub>1.1 voltage-sensing domain III exclusively controls skeletal muscle excitation-contraction coupling.
basic_science · Level V
Where this comes from
- Record sourced from PubMed, PMID 39198449.
- Also identified by DOI 10.1038/s41467-024-51809-5 and PMC identifier 11358481.
- Licence recorded as CC BY.
- The licence permits redistribution, so the abstract is shown in full and the full text is available from the publisher.
Abstract
Skeletal muscle contractions are initiated by action potentials, which are sensed by the voltage-gated calcium channel (Ca<sub>V</sub>1.1) and are conformationally coupled to calcium release from intracellular stores. Notably, Ca<sub>V</sub>1.1 contains four separate voltage-sensing domains (VSDs), which activate channel gating and excitation-contraction (EC-) coupling at different voltages and with distinct kinetics. Here we show that a single VSD of Ca<sub>V</sub>1.1 controls skeletal muscle EC-coupling. Whereas mutations in VSDs I, II and IV affect the current properties but not EC-coupling, only mutations in VSD III alter the voltage-dependence of depolarization-induced calcium release. Molecular dynamics simulations reveal comprehensive, non-canonical state transitions of VSD III in response to membrane depolarization. Identifying the voltage sensor that activates EC-coupling and detecting its unique conformational changes opens the door to unraveling the downstream events linking VSD III motion to the opening of the calcium release channel, and thus resolving the signal transduction mechanism of skeletal muscle EC-coupling.
Medical subject headings
- Calcium
- Calcium Channels, L-Type
- Excitation Contraction Coupling
- Molecular Dynamics Simulation
- Muscle, Skeletal
- Protein Domains