The skeletal muscle ryanodine receptor isoform 1 is found at the intercalated discs in human and mouse hearts

• Published in: Journal of muscle research and cell motility 2002-01, Vol.23 (4), p.285-292
• Main Authors: Jeyakumar, Loice H, Gleaves, Linda A, Ridley, Bettye D, Chang, Paul, Atkinson, James, Barnett, Joey V, Fleischer, Sidney
• Format: Article
• Language: English
• Subjects: Animals; Antibodies; Calcium; Calcium (intracellular); Calcium channels; Calcium release channels; Calcium Signaling - physiology; Cardiac muscle; Cell signaling; Connexin 43; Connexin 43 - metabolism; Depolarization; Fluorescent Antibody Technique; Humans; Immunoprecipitation; Intracellular; Intracellular signalling; Isoforms; Male; Mice; Muscle Contraction - physiology; Muscle, Skeletal - metabolism; Muscular system; Myocardium - cytology; Myocardium - metabolism; Myocytes, Cardiac - cytology; Myocytes, Cardiac - metabolism; Protein Isoforms - metabolism; Rodents; Ryanodine Receptor Calcium Release Channel - metabolism; Ryanodine receptors; Sarcoplasmic reticulum; Skeletal muscle; Subcellular Fractions
• ISSN: 0142-4319; 1573-2657
• DOI: 10.1023/A:1022091931677

The ryanodine receptors (RyRs) are a class of intracellular calcium release channels of which there are three isoforms. In striated muscle, isoform 1 and isoform 2 are mainly expressed in the terminal cisternae of sarcoplasmic reticulum of skeletal muscle and heart, respectively. Isoform 3 is widely distributed in tissues but in minuscule amounts. These channels release calcium ions from intracellular stores in excitation-contraction coupling for cell signaling. Here, we report the presence of skeletal muscle isoform 1 localized in the intercalated discs (IDs) of human and mouse hearts. By using RyR1 and connexin43 specific antibodies and dual immunofluorescent techniques, both were localized in the proximity of the IDs of human and mouse hearts. We confirmed that RyR1 is localized to the IDs by selective immunoprecipitation of RyR isoform 1 from a subcellular fraction containing IDs from human heart tissue. The functional significance of our observation remains to be elucidated as isoform 1 is involved in depolarization induced calcium release, unlike RyR isoforms 2 and 3 which appear to be involved in calcium induced calcium release.