Triadin binding to the C-terminal luminal loop of the ryanodine receptor is important for skeletal muscle excitation contraction coupling.

Abstract : Ca(2+) release from intracellular stores is controlled by complex interactions between multiple proteins. Triadin is a transmembrane glycoprotein of the junctional sarcoplasmic reticulum of striated muscle that interacts with both calsequestrin and the type 1 ryanodine receptor (RyR1) to communicate changes in luminal Ca(2+) to the release machinery. However, the potential impact of the triadin association with RyR1 in skeletal muscle excitation-contraction coupling remains elusive. Here we show that triadin binding to RyR1 is critically important for rapid Ca(2+) release during excitation-contraction coupling. To assess the functional impact of the triadin-RyR1 interaction, we expressed RyR1 mutants in which one or more of three negatively charged residues (D4878, D4907, and E4908) in the terminal RyR1 intraluminal loop were mutated to alanines in RyR1-null (dyspedic) myotubes. Coimmunoprecipitation revealed that triadin, but not junctin, binding to RyR1 was abolished in the triple (D4878A/D4907A/E4908A) mutant and one of the double (D4907A/E4908A) mutants, partially reduced in the D4878A/D4907A double mutant, but not affected by either individual (D4878A, D4907A, E4908A) mutations or the D4878A/E4908A double mutation. Functional studies revealed that the rate of voltage- and ligand-gated SR Ca(2+) release were reduced in proportion to the degree of interruption in triadin binding. Ryanodine binding, single channel recording, and calcium release experiments conducted on WT and triple mutant channels in the absence of triadin demonstrated that the luminal loop mutations do not directly alter RyR1 function. These findings demonstrate that junctin and triadin bind to different sites on RyR1 and that triadin plays an important role in ensuring rapid Ca(2+) release during excitation-contraction coupling in skeletal muscle.
Type de document :
Article dans une revue
The Journal of General Physiology, 2007, 130 (4), pp.365-78. 〈10.1085/jgp.200709790〉
Liste complète des métadonnées

Littérature citée [35 références]  Voir  Masquer  Télécharger

http://www.hal.inserm.fr/inserm-00381948
Contributeur : Nathalie Roux-Buisson <>
Soumis le : mercredi 8 juillet 2009 - 17:08:49
Dernière modification le : jeudi 5 octobre 2017 - 15:36:08
Document(s) archivé(s) le : jeudi 10 juin 2010 - 22:52:44

Fichier

JGenPhys_Dirksen.pdf
Fichiers éditeurs autorisés sur une archive ouverte

Identifiants

Collections

CEA | U836 | UGA

Citation

Sanjeewa Goonasekera, Nicole Beard, Linda Groom, Takashi Kimura, Alla Lyfenko, et al.. Triadin binding to the C-terminal luminal loop of the ryanodine receptor is important for skeletal muscle excitation contraction coupling.. The Journal of General Physiology, 2007, 130 (4), pp.365-78. 〈10.1085/jgp.200709790〉. 〈inserm-00381948〉

Partager

Métriques

Consultations de la notice

154

Téléchargements de fichiers

216