{"title":"The foundation of excitation-contraction coupling in skeletal muscle: communication between the transverse tubules and sarcoplasmic reticulum.","authors":"Jack A Rall","doi":"10.1152/advan.00086.2024","DOIUrl":null,"url":null,"abstract":"<p><p>The expression excitation-contraction (EC) coupling in skeletal muscle was coined in 1952 (Sandow A. <i>Yale J Biol Med</i> 25: 176-201, 1952). The term evolved narrowly to include only the processes at the triad that intervene between depolarization of the transverse tubular (T-tubular) membrane and Ca<sup>2+</sup> release from the sarcoplasmic reticulum (SR). From 1970 to 1988, the foundation of EC coupling was elucidated. The channel through which Ca<sup>2+</sup> was released during activation was located in the SR by its specific binding to the plant insecticide ryanodine. This channel was called the ryanodine receptor (RyR). The RyR contained four subunits that together constituted the \"SR foot\" structure that traversed the gap between the SR and the T-tubular membrane. Ca<sup>2+</sup> channels, also called dihydropyridine receptors (DHPRs), were located in the T-tubular membrane at the triadic junction and shown to be essential for EC coupling. There was a precise relationship between the two channels. Four DHPRs, organized as tetrads, were superimposed on alternate RyRs. This structure was consistent with the proposal that EC coupling was mediated via a movement of intramembrane charge in the T-tubular system. The speculation was that the DHPR acted as a voltage sensor transferring information to the RyRs of the SR by protein-protein interaction causing the release of Ca<sup>2+</sup> from the SR. A great deal of progress was made by 1988 toward understanding EC coupling. However, the ultimate question of how voltage sensing is coupled to the opening of the SR Ca<sup>2+</sup> release channel remains unresolved.<b>NEW & NOTEWORTHY</b> The least understood part of the series of events in excitation-contraction coupling in skeletal muscle was how information was transmitted from the transverse tubules to the sarcoplasmic (SR) and how Ca<sup>2+</sup> was released from the SR. Through an explosion of technical approaches including physiological, biochemical, structural, pharmacological, and molecular genetics, much was discovered between 1970 and 1988. By the end of 1988, the foundation of EC coupling in skeletal muscle was established.</p>","PeriodicalId":50852,"journal":{"name":"Advances in Physiology Education","volume":null,"pages":null},"PeriodicalIF":1.7000,"publicationDate":"2024-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Advances in Physiology Education","FirstCategoryId":"95","ListUrlMain":"https://doi.org/10.1152/advan.00086.2024","RegionNum":4,"RegionCategory":"教育学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"2024/8/8 0:00:00","PubModel":"Epub","JCR":"Q2","JCRName":"EDUCATION, SCIENTIFIC DISCIPLINES","Score":null,"Total":0}
引用次数: 0
Abstract
The expression excitation-contraction (EC) coupling in skeletal muscle was coined in 1952 (Sandow A. Yale J Biol Med 25: 176-201, 1952). The term evolved narrowly to include only the processes at the triad that intervene between depolarization of the transverse tubular (T-tubular) membrane and Ca2+ release from the sarcoplasmic reticulum (SR). From 1970 to 1988, the foundation of EC coupling was elucidated. The channel through which Ca2+ was released during activation was located in the SR by its specific binding to the plant insecticide ryanodine. This channel was called the ryanodine receptor (RyR). The RyR contained four subunits that together constituted the "SR foot" structure that traversed the gap between the SR and the T-tubular membrane. Ca2+ channels, also called dihydropyridine receptors (DHPRs), were located in the T-tubular membrane at the triadic junction and shown to be essential for EC coupling. There was a precise relationship between the two channels. Four DHPRs, organized as tetrads, were superimposed on alternate RyRs. This structure was consistent with the proposal that EC coupling was mediated via a movement of intramembrane charge in the T-tubular system. The speculation was that the DHPR acted as a voltage sensor transferring information to the RyRs of the SR by protein-protein interaction causing the release of Ca2+ from the SR. A great deal of progress was made by 1988 toward understanding EC coupling. However, the ultimate question of how voltage sensing is coupled to the opening of the SR Ca2+ release channel remains unresolved.NEW & NOTEWORTHY The least understood part of the series of events in excitation-contraction coupling in skeletal muscle was how information was transmitted from the transverse tubules to the sarcoplasmic (SR) and how Ca2+ was released from the SR. Through an explosion of technical approaches including physiological, biochemical, structural, pharmacological, and molecular genetics, much was discovered between 1970 and 1988. By the end of 1988, the foundation of EC coupling in skeletal muscle was established.
期刊介绍:
Advances in Physiology Education promotes and disseminates educational scholarship in order to enhance teaching and learning of physiology, neuroscience and pathophysiology. The journal publishes peer-reviewed descriptions of innovations that improve teaching in the classroom and laboratory, essays on education, and review articles based on our current understanding of physiological mechanisms. Submissions that evaluate new technologies for teaching and research, and educational pedagogy, are especially welcome. The audience for the journal includes educators at all levels: K–12, undergraduate, graduate, and professional programs.