Physiology, Ryanodine Receptor

Excerpt

A ryanodine receptor is a homotetrameric channel with a molecular mass of more than 2.2 megadaltons. It is the largest known ion channel and gets its name from one of its exogenous ligands, ryanodine, an alkaloid plant toxin from Ryania speciosa. Ryanodine receptor ion channels are embedded in the internal side of the sarcoplasmic reticulum that stores calcium, which is fundamental to striated muscle. They are high-conductance, monovalent, or divalent conducting channels regulated by multiple factors, including calcium, magnesium, adenosine triphosphate, calmodulin, protein kinases and phosphatases, and redox-active species. Ryanodine receptors are essential for excitation-contraction coupling, linking action potentials and contraction of the striated muscle by releasing calcium ions required to activate the contractile proteins. These proteins are studied to develop therapeutic advances in diseases associated with striated muscle.