Figure 4.

Model of the homotetrameric ryanodine receptor, the calcium release channel situated in the membrane of the sarcoplasmic reticulum (SR). The cytosolic part of the protein complex, the so-called foot, bridges the gap between the transverse tubular system and the SR. Mutations have been described for the skeletal muscle ryanodine receptor (RyR1), which cause susceptibility to malignant hyperthermia (MHS) and central core disease (CCD). Conventional 1-letter abbreviations are used for the replaced amino acids.