A voltage-gated calcium-release channel complex of the sarcoplasmic or endoplasmic reticulum. It plays an important role in the excitation-contraction (E-C) coupling of muscle cells. RyR comprises a family of ryanodine receptors, widely expressed throughout the animal kingdom.
Comment:
An example of this is RyR1 in rabbit (P11716) in PMID:2550460 (inferred from electron microscopy).