Coupled Gating Between Individual Skeletal Muscle Ca 2+ Release Channels (Ryanodine Receptors)

Abstract

Excitation-contraction coupling in skeletal muscle requires the release of intracellular calcium ions (Ca 2+ ) through ryanodine receptor (RyR1) channels in the sarcoplasmic reticulum. Half of the RyR1 channels are activated by voltage-dependent Ca 2+ channels in the plasma membrane. In planar lipid bilayers, RyR1 channels exhibited simultaneous openings and closings, termed “coupled gating.” Addition of the channel accessory protein FKBP12 induced coupled gating, and removal of FKBP12 uncoupled channels. Coupled gating provides a mechanism by which RyR1 channels that are not associated with voltage-dependent Ca 2+ channels can be regulated.