European Biophysics Journal

, 39:27 | Cite as

Ca2+ signaling in striated muscle: the elusive roles of triadin, junctin, and calsequestrin

  • Nicole A. Beard
  • Lan Wei
  • Angela Fay Dulhunty


This review focuses on molecular interactions between calsequestrin, triadin, junctin and the ryanodine receptor in the lumen of the sarcoplasmic reticulum. These interactions modulate changes in Ca2+ release in response to changes in the Ca2+ load within the sarcoplasmic reticulum store in striated muscle and are of fundamental importance to Ca2+ homeostasis, since massive adaptive changes occur when expression of the proteins is manipulated, while mutations in calsequestrin lead to functional changes which can be fatal. We find that calsequestrin plays a different role in the heart and skeletal muscle, enhancing Ca2+ release in the heart, but depressing Ca2+ release in skeletal muscle. We also find that triadin and junctin exert independent influences on the ryanodine receptor in skeletal muscle where triadin alone modifies excitation–contraction coupling, while junctin alone supports functional interactions between calsequestrin and the ryanodine receptor.


Triadin Junctin Calsequestrin Ryanodine receptors 


  1. Beard NA, Sakowska MM, Dulhunty AF et al (2002) Calsequestrin is an inhibitor of skeletal muscle ryanodine receptor calcium release channels. Biophys J 82:310–320. doi: 10.1016/S0006-3495(02)75396-4 CrossRefPubMedGoogle Scholar
  2. Beard NA, Laver DR, Dulhunty AF (2004) Calsequestrin and the calcium release channel of skeletal and cardiac muscle. Prog Biophys Mol Biol 85:33–69. doi: 10.1016/j.pbiomolbio.2003.07.001 CrossRefPubMedGoogle Scholar
  3. Beard NA, Casarotto MG, Wei L et al (2005) Regulation of ryanodine receptors by calsequestrin: effect of high luminal Ca2+ and phosphorylation. Biophys J 88:3444–3454. doi: 10.1529/biophysj.104.051441 CrossRefPubMedGoogle Scholar
  4. Biral D, Volpe P, Damiani E et al (1992) Coexistence of two calsequestrin isoforms in rabbit slow-twitch skeletal muscle fibers. FEBS Lett 299:175–178. doi: 10.1016/0014-5793(92)80241-8 CrossRefPubMedGoogle Scholar
  5. Brandt NR, Caswell AH, Brunschwig JP et al (1992) Effects of anti-triadin antibody on Ca2+ release from sarcoplasmic reticulum. FEBS Lett 299:57–59. doi: 10.1016/0014-5793(92)80100-U CrossRefPubMedGoogle Scholar
  6. Caswell AH, Brandt NR, Brunschwig JP et al (1991) Localization and partial characterization of the oligomeric disulfide-linked molecular weight 95,000 protein (triadin) which binds the ryanodine and dihydropyridine receptors in skeletal muscle triadic vesicles. Biochemistry 30:7507–7513. doi: 10.1021/bi00244a020 CrossRefPubMedGoogle Scholar
  7. Damiani E, Margreth A (1994) Characterization study of the ryanodine receptor and of calsequestrin isoforms of mammalian skeletal muscles in relation to fibre types. J Muscle Res Cell Motil 15:86–101. doi: 10.1007/BF00130421 CrossRefPubMedGoogle Scholar
  8. Dirksen WP, Lacombe VA, Chi M et al (2007) A mutation in calsequestrin, CASQ2D307H, impairs sarcoplasmic reticulum Ca2+ handling and causes complex ventricular arrhythmias in mice. Cardiovasc Res 75:69–78. doi: 10.1016/j.cardiores.2007.03.002 CrossRefPubMedGoogle Scholar
  9. Fan H, Brandt NR, Caswell AH (1995) Disulfide bonds, N-glycosylation and transmembrane topology of skeletal muscle triadin. Biochemistry 34:14902–14908. doi: 10.1021/bi00045a035 CrossRefPubMedGoogle Scholar
  10. Fan GC, Yuan Q, Zhao W et al (2007) Junctin is a prominent regulator of contractility in cardiomyocytes. Biochem Biophys Res Commun 352:617–622. doi: 10.1016/j.bbrc.2006.11.093 CrossRefPubMedGoogle Scholar
  11. Fliegel L, Newton E, Burns K et al (1990) Molecular cloning of cDNA encoding a 55-kDa multifunctional thyroid hormone binding protein of skeletal muscle sarcoplasmic reticulum. J Biol Chem 265:15496–15502PubMedGoogle Scholar
  12. Franzini-Armstrong C, Protasi F, Tijskens P (2005) The assembly of calcium release units in cardiac muscle. Ann N Y Acad Sci 1047:76–85. doi: 10.1196/annals.1341.007 CrossRefPubMedGoogle Scholar
  13. Glover L, Culligan K, Cala S et al (2001) Calsequestrin binds to monomeric and complexed forms of key calcium-handling proteins in native sarcoplasmic reticulum membranes from rabbit skeletal muscle. Biochim Biophys Acta 1515:120–132. doi: 10.1016/S0005-2736(01)00406-0 CrossRefPubMedGoogle Scholar
  14. Goonasekera SA, Beard NA, Groom L et al (2007) Triadin binding to the C-terminal luminal loop of the ryanodine receptor is important for skeletal muscle excitation contraction coupling. J Gen Physiol 130:365–378. doi: 10.1085/jgp.200709790 CrossRefPubMedGoogle Scholar
  15. Groh S, Marty I, Ottolia M et al (1999) Functional interaction of the cytoplasmic domain of triadin with the skeletal ryanodine receptor. J Biol Chem 274:12278–12283. doi: 10.1074/jbc.274.18.12278 CrossRefPubMedGoogle Scholar
  16. Guo W, Jorgensen AO, Jones LR et al (1996) Biochemical characterization and molecular cloning of cardiac triadin. J Biol Chem 271:458–465. doi: 10.1074/jbc.271.1.458 CrossRefPubMedGoogle Scholar
  17. Gyorke I, Hester N, Jones LR et al (2004) The role of calsequestrin, triadin, and junctin in conferring cardiac ryanodine receptor responsiveness to luminal calcium. Biophys J 86:2121–2128. doi: 10.1016/S0006-3495(04)74271-X CrossRefPubMedGoogle Scholar
  18. Hong CS, Cho MC, Kwak YG et al (2002) Cardiac remodeling and atrial fibrillation in transgenic mice overexpressing junctin. FASEB J 16:1310–1312PubMedGoogle Scholar
  19. Houle TD, Ram ML, Cala SE (2004) Calsequestrin mutant D307H exhibits depressed binding to its protein targets and a depressed response to calcium. Cardiovasc Res 64:227–233. doi: 10.1016/j.cardiores.2004.09.009 CrossRefPubMedGoogle Scholar
  20. Kim E, Youn B, Kemper L et al (2007) Characterization of human cardiac calsequestrin and its deleterious mutants. J Mol Biol 373:1047–1057. doi: 10.1016/j.jmb.2007.08.055 CrossRefPubMedGoogle Scholar
  21. Kimura T, Nakamori M, Lueck JD et al (2005) Altered mRNA splicing of the skeletal muscle ryanodine receptor and sarcoplasmic/endoplasmic reticulum Ca2+-ATPase in myotonic dystrophy type 1. Hum Mol Genet 14:2189–2200. doi: 10.1093/hmg/ddi223 CrossRefPubMedGoogle Scholar
  22. Kimura T, Pace SM, Wei L et al (2007) A variably spliced region in the type 1 ryanodine receptor may participate in an inter-domain interaction. Biochem J 401:317–324. doi: 10.1042/BJ20060686 CrossRefPubMedGoogle Scholar
  23. Kimura T, Lueck JD, Harvey PJ et al (2009) Alternative splicing of RyR1 alters the efficacy of skeletal EC coupling. Cell Calcium (in press)Google Scholar
  24. Kirchhefer U, Neumann J, Baba HA et al (2001) Cardiac hypertrophy and impaired relaxation in transgenic mice overexpressing triadin 1. J Biol Chem 276:4142–4149. doi: 10.1074/jbc.M006443200 CrossRefPubMedGoogle Scholar
  25. Kirchhefer U, Neumann J, Bers DM et al (2003) Impaired relaxation in transgenic mice overexpressing junctin. Cardiovasc Res 59:369–379. doi: 10.1016/S0008-6363(03)00432-2 CrossRefPubMedGoogle Scholar
  26. Kirchhefer U, Hanske G, Jones LR et al (2006) Overexpression of junctin causes adaptive changes in cardiac myocyte Ca(2+) signaling. Cell Calcium 39:131–142. doi: 10.1016/j.ceca.2005.10.004 CrossRefPubMedGoogle Scholar
  27. Kirchhof P, Klimas J, Fabritz L et al (2007) Stress and high heart rate provoke ventricular tachycardia in mice expressing triadin. J Mol Cell Cardiol 42:962–971. doi: 10.1016/j.yjmcc.2007.02.012 CrossRefPubMedGoogle Scholar
  28. Knollmann BC, Chopra N, Hlaing T et al (2006) Casq2 deletion causes sarcoplasmic reticulum volume increase, premature Ca2+ release, and catecholaminergic polymorphic ventricular tachycardia. J Clin Invest 116:2510–2520PubMedGoogle Scholar
  29. Knudson CM, Stang KK, Jorgensen AO et al (1993a) Biochemical characterization of ultrastructural localization of a major junctional sarcoplasmic reticulum glycoprotein (triadin). J Biol Chem 268:12637–12645PubMedGoogle Scholar
  30. Knudson CM, Stang KK, Moomaw CR et al (1993b) Primary structure and topological analysis of a skeletal muscle-specific junctional sarcoplasmic reticulum glycoprotein (triadin). J Biol Chem 268:12646–12654PubMedGoogle Scholar
  31. Launikonis BS, Zhou J, Royer L et al (2006) Depletion “skraps” and dynamic buffering inside the cellular calcium store. Proc Natl Acad Sci USA 103:2982–2987. doi: 10.1073/pnas.0511252103 CrossRefPubMedGoogle Scholar
  32. Lee JM, Rho SH, Shin DW et al (2004) Negatively charged amino acids within the intraluminal loop of ryanodine receptor are involved in the interaction with triadin. J Biol Chem 279:6994–7000. doi: 10.1074/jbc.M312446200 CrossRefPubMedGoogle Scholar
  33. Ohkura M, Furukawa K, Fujimori H et al (1998) Dual regulation of the skeletal muscle ryanodine receptor by triadin and calsequestrin. Biochemistry 37:12987–12993. doi: 10.1021/bi972803d CrossRefPubMedGoogle Scholar
  34. Paolini C, Quarta M, Nori A et al (2007) Reorganized stores and impaired calcium handling in skeletal muscle of mice lacking calsequestrin-1. J Physiol 583:767–784. doi: 10.1113/jphysiol.2007.138024 CrossRefPubMedGoogle Scholar
  35. Park H, Park IY, Kim E et al (2004) Comparing skeletal and cardiac calsequestrin structures and their calcium binding: a proposed mechanism for coupled calcium binding and protein polymerization. J Biol Chem 279:18026–18033. doi: 10.1074/jbc.M311553200 CrossRefPubMedGoogle Scholar
  36. Qin J, Valle G, Nani A et al (2008) Luminal Ca2+ regulation of single cardiac ryanodine receptors: insights provided by calsequestrin and its mutants. J Gen Physiol 131:325–334. doi: 10.1085/jgp.200709907 CrossRefPubMedGoogle Scholar
  37. Rezgui SS, Vassilopoulos S, Brocard J et al (2005) Triadin (Trisk 95) overexpression blocks excitation–contraction coupling in rat skeletal myotubes. J Biol Chem 280:39302–39308. doi: 10.1074/jbc.M506566200 CrossRefPubMedGoogle Scholar
  38. Rizzi N, Liu N, Napolitano C et al (2008) Unexpected structural and functional consequences of the R33Q homozygous mutation in cardiac calsequestrin: a complex arrhythmogenic cascade in a knock in mouse model. Circ Res 103:298–306. doi: 10.1161/CIRCRESAHA.108.171660 CrossRefPubMedGoogle Scholar
  39. Scott BT, Simmerman HK, Collins JH et al (1988) Complete amino acid sequence of canine cardiac calsequestrin deduced by cDNA cloning. J Biol Chem 263:8958–8964PubMedGoogle Scholar
  40. Shen X, Franzini-Armstrong C, Lopez JR et al (2007) Triadins modulate intracellular Ca(2+) homeostasis but are not essential for excitation–contraction coupling in skeletal muscle. J Biol Chem 282:37864–37874. doi: 10.1074/jbc.M705702200 CrossRefPubMedGoogle Scholar
  41. Slupsky JR, Ohnishi M, Carpenter MR et al (1987) Characterization of cardiac calsequestrin. Biochemistry 26:6539–6544. doi: 10.1021/bi00394a038 CrossRefPubMedGoogle Scholar
  42. Song L, Alcalai R, Arad M et al (2007) Calsequestrin 2 (CASQ2) mutations increase expression of calreticulin and ryanodine receptors, causing catecholaminergic polymorphic ventricular tachycardia. J Clin Invest 117:1814–1823. doi: 10.1172/JCI31080 CrossRefPubMedGoogle Scholar
  43. Szegedi C, Sarkozi S, Herzog A et al (1999) Calsequestrin: more than ‘only’ a luminal Ca2+ buffer inside the sarcoplasmic reticulum. Biochem J 337(Pt 1):19–22. doi: 10.1042/0264-6021:3370019 CrossRefPubMedGoogle Scholar
  44. Terentyev D, Cala SE, Houle TD et al (2005) Triadin overexpression stimulates excitation–contraction coupling and increases predisposition to cellular arrhythmia in cardiac myocytes. Circ Res 96:651–658. doi: 10.1161/01.RES.0000160609.98948.25 CrossRefPubMedGoogle Scholar
  45. Terentyev D, Kubalova Z, Valle G et al (2008) Modulation of SR Ca release by luminal Ca and calsequestrin in cardiac myocytes: Effects of CASQ2 mutations linked to sudden cardiac death. Biophys JGoogle Scholar
  46. Valle G, Galla D, Nori A et al (2008) Catecholaminergic polymorphic ventricular tachycardia-related mutations R33Q and L167H alter calcium sensitivity of human cardiac calsequestrin. Biochem J 413:291–303. doi: 10.1042/BJ20080163 CrossRefPubMedGoogle Scholar
  47. Vassilopoulos S, Thevenon D, Rezgui SS et al (2005) Triadins are not triad-specific proteins: two new skeletal muscle triadins possibly involved in the architecture of sarcoplasmic reticulum. J Biol Chem 280:28601–28609. doi: 10.1074/jbc.M501484200 CrossRefPubMedGoogle Scholar
  48. Viatchenko-Karpinski S, Terentyev D, Gyorke I et al (2004) Abnormal calcium signaling and sudden cardiac death associated with mutation of calsequestrin. Circ Res 94:471–477. doi: 10.1161/01.RES.0000115944.10681.EB CrossRefPubMedGoogle Scholar
  49. Wang S, Trumble WR, Liao H et al (1998) Crystal structure of calsequestrin from rabbit skeletal muscle sarcoplasmic reticulum. Nat Struct Biol 5:476–483. doi: 10.1038/nsb0698-476 CrossRefPubMedGoogle Scholar
  50. Wang Y, Xu L, Duan H et al (2006) Knocking down type 2 but not type 1 calsequestrin reduces calcium sequestration and release in C2C12 skeletal muscle myotubes. J Biol Chem 281:15572–15581. doi: 10.1074/jbc.M600090200 CrossRefPubMedGoogle Scholar
  51. Wang Y, Li X, Duan H et al (2008) Altered stored calcium release in skeletal myotubes deficient of triadin and junctin. Cell CalciumGoogle Scholar
  52. Wei L, Varsanyi M, Dulhunty AF et al (2006) The conformation of calsequestrin determines its ability to regulate skeletal ryanodine receptors. Biophys J 91:1288–1301. doi: 10.1529/biophysj.106.082610 CrossRefPubMedGoogle Scholar
  53. Wei L, Abdellatif YA, Liu D et al (2008) Muscle-specific GSTM2-2 on the luminal side of the sarcoplasmic reticulum modifies RyR ion channel activity. Int J Biochem Cell Biol 40:1616–1628. doi: 10.1016/j.biocel.2007.12.019 CrossRefPubMedGoogle Scholar
  54. Wei L, Gallant EM, Dulhunty AF et al (2009a) Junctin and triadin activate skeletal ryanodine receptors; junctin alone mediates functional interactions with calsequestrin. Int J Biochem Cell Biol (in press)Google Scholar
  55. Wei L, Hanna AD, Beard NA et al (2009b) Unique properties of calsequestrin in the heart. Cell Calcium (in press). doi: 10.1016/j.ceca.2009.03.006
  56. Yuan Q, Fan GC, Dong M et al (2007) Sarcoplasmic reticulum calcium overloading in junctin deficiency enhances cardiac contractility but increases ventricular automaticity. Circulation 115:300–309. doi: 10.1161/CIRCULATIONAHA.106.654699 CrossRefPubMedGoogle Scholar
  57. Zhang L, Kelley J, Schmeisser G et al (1997) Complex formation between junctin, triadin, calsequestrin, and the ryanodine receptor. Proteins of the cardiac junctional sarcoplasmic reticulum membrane. J Biol Chem 272:23389–23397. doi: 10.1074/jbc.272.37.23389 CrossRefPubMedGoogle Scholar

Copyright information

© European Biophysical Societies' Association 2009

Authors and Affiliations

  • Nicole A. Beard
    • 1
  • Lan Wei
    • 2
  • Angela Fay Dulhunty
    • 1
  1. 1.Muscle Research Group, John Curtin School of Medical ResearchAustralian National UniversityCanberraAustralia
  2. 2.Department of Pharmacology and PhysiologyUniversity of Rochester Medical CenterRochesterUSA

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