Comparison of the calcium release channel of cardiac and skeletal muscle sarcoplasmic reticulum by target inactivation analysis

• Published in: Biochemistry (Easton) Vol. 28; no. 3; pp. 1319 - 1323
• Main Authors: McGrew, Susan G, Inui, Makoto, Chadwick, Christopher C, Boucek, Robert J, Jung, Chan Y, Fleischer, Sidney
• Format: Journal Article
• Language: English
• Published: United States American Chemical Society 07.02.1989
• Subjects: 560120 - Radiation Effects on Biochemicals, Cells, & Tissue Culture; ALKALINE EARTH METAL COMPOUNDS; Alkaloids - metabolism; Animals; BEAMS; BIOLOGICAL EFFECTS; BIOLOGICAL RADIATION EFFECTS; BODY; Calcium Channels - metabolism; Calcium Channels - radiation effects; CALCIUM COMPOUNDS; CARDIOVASCULAR SYSTEM; CATIONS; CELL CONSTITUENTS; CHARGED PARTICLES; ELECTRON BEAMS; ENDOPLASMIC RETICULUM; HEART; HYDROGEN COMPOUNDS; INACTIVATION; IONS; LEPTON BEAMS; MEMBRANE PROTEINS; Microsomes - metabolism; MOLECULAR STRUCTURE; MOLECULAR WEIGHT; MUSCLES; Muscles - metabolism; Myocardium - metabolism; Organ Specificity; ORGANIC COMPOUNDS; ORGANOIDS; ORGANS; PARTICLE BEAMS; PEPTIDES; POLYPEPTIDES; PROTEINS; RADIATION EFFECTS; RADIATION, THERMAL, AND OTHER ENVIRON. POLLUTANT EFFECTS ON LIVING ORGS. AND BIOL. MAT; RECEPTORS; Receptors, Cholinergic - metabolism; Ryanodine - metabolism; Ryanodine Receptor Calcium Release Channel; SARCOPLASMIC RETICULUM; Sarcoplasmic Reticulum - metabolism; SKELETON; TRITIUM COMPOUNDS
• ISSN: 0006-2960; 1520-4995
• DOI: 10.1021/bi00429a056

The calcium release channel of sarcoplasmic reticulum which triggers muscle contraction in excitation-contraction coupling has recently been isolated. The channel has been found to be morphologically identical with the feet structures of the junctional face membrane of terminal cisternae and consists of an oligomer of a unique high molecular weight polypeptide. In this study, we compare the target size of the calcium release channel from heart and skeletal muscle using target inactivation analysis. The target molecular weights of the calcium release channel estimated by measuring ryanodine binding after irradiation are similar for heart (139,000) and skeletal muscle (143,000) and are smaller than the monomeric unit (estimated to be about 360,000). The target size, estimated by measuring polypeptide remaining after irradiation, was essentially the same for heart and skeletal muscle, 1,061,000 and 1,070,000, respectively, indicating an oligomeric association of protomers. Thus, the calcium release channel of both cardiac and skeletal muscle reacts uniquely with regard to target inactivation analysis in that (1) the size by ryanodine binding is smaller than the monomeric unit and (2) a single hit leads to destruction of more than one polypeptide, by measuring polypeptide remaining. Our target inactivation analysis studies indicate that heart and skeletal muscle receptors are structurally very similar.