titin

Summary

Gene Symbol: titin
Description: titin
Alias: CMD1G, CMH9, CMPD4, EOMFC, HMERF, LGMD2J, MYLK5, SALMY, TMD, titin, connectin, rhabdomyosarcoma antigen MU-RMS-40.14
Species: human
Products:     titin

Top Publications

  1. Watanabe K, Nair P, Labeit D, Kellermayer M, Greaser M, Labeit S, et al. Molecular mechanics of cardiac titin's PEVK and N2B spring elements. J Biol Chem. 2002;277:11549-58 pubmed
    b>Titin is a giant elastic protein that is responsible for the majority of passive force generated by the myocardium...
  2. Mayans O, van der Ven P, Wilm M, Mues A, Young P, Fürst D, et al. Structural basis for activation of the titin kinase domain during myofibrillogenesis. Nature. 1998;395:863-9 pubmed
    The giant muscle protein titin (connectin) is essential in the temporal and spatial control of the assembly of the highly ordered sarcomeres (contractile units) of striated muscle...
  3. Labeit D, Watanabe K, Witt C, Fujita H, Wu Y, Lahmers S, et al. Calcium-dependent molecular spring elements in the giant protein titin. Proc Natl Acad Sci U S A. 2003;100:13716-21 pubmed
    Titin (also known as connectin) is a giant protein with a wide range of cellular functions, including providing muscle cells with elasticity...
  4. Hayashi C, Ono Y, Doi N, Kitamura F, Tagami M, Mineki R, et al. Multiple molecular interactions implicate the connectin/titin N2A region as a modulating scaffold for p94/calpain 3 activity in skeletal muscle. J Biol Chem. 2008;283:14801-14 pubmed publisher
    ..In addition, a small in-frame deletion in the N2A region of connectin/titin that impairs p94-connectin interaction causes a severe muscular dystrophy (mdm) in mice...
  5. Penisson Besnier I, Hackman P, Suominen T, Sarparanta J, Huovinen S, Richard Crémieux I, et al. Myopathies caused by homozygous titin mutations: limb-girdle muscular dystrophy 2J and variations of phenotype. J Neurol Neurosurg Psychiatry. 2010;81:1200-2 pubmed publisher
    Limb-girdle muscular dystrophy 2J caused by mutations in C-terminal titin has so far been identified in Finnish patients only. This may in part be due to limited availability of diagnostic tests for titin defects...
  6. Bucher R, Svergun D, Muhle Goll C, Mayans O. The structure of the FnIII Tandem A77-A78 points to a periodically conserved architecture in the myosin-binding region of titin. J Mol Biol. 2010;401:843-53 pubmed publisher
    b>Titin is a large intrasarcomeric protein that, among its many roles in muscle, is thought to modulate the in vivo assembly of the myosin motor filament...
  7. Bertz M, Wilmanns M, Rief M. The titin-telethonin complex is a directed, superstable molecular bond in the muscle Z-disk. Proc Natl Acad Sci U S A. 2009;106:13307-133310 pubmed publisher
    ..In skeletal muscle, the giant protein titin is anchored in the Z-disk by telethonin...
  8. Granzier H, Radke M, Royal J, Wu Y, Irving T, Gotthardt M, et al. Functional genomics of chicken, mouse, and human titin supports splice diversity as an important mechanism for regulating biomechanics of striated muscle. Am J Physiol Regul Integr Comp Physiol. 2007;293:R557-67 pubmed
    b>Titin is a giant filamentous elastic protein that spans from the Z-disk to M-band regions of the sarcomere. The I-band region of titin is extensible and develops passive force in stretched sarcomeres...
  9. Herman D, Lam L, Taylor M, Wang L, Teekakirikul P, Christodoulou D, et al. Truncations of titin causing dilated cardiomyopathy. N Engl J Med. 2012;366:619-28 pubmed publisher
    ..TTN, the gene encoding the sarcomere protein titin, has been insufficiently analyzed for cardiomyopathy mutations because of its enormous size...

More Information

Publications63

  1. Miller M, Bang M, Witt C, Labeit D, Trombitas C, Watanabe K, et al. The muscle ankyrin repeat proteins: CARP, ankrd2/Arpp and DARP as a family of titin filament-based stress response molecules. J Mol Biol. 2003;333:951-64 pubmed
    ..MARP family members contain within their ankyrin repeat region a binding site for the myofibrillar elastic protein titin. Within the myofibril, MARPs, myopalladin, and the calpain protease p94 appear to be components of a titin N2A-..
  2. Guo W, Schafer S, Greaser M, Radke M, Liss M, Govindarajan T, et al. RBM20, a gene for hereditary cardiomyopathy, regulates titin splicing. Nat Med. 2012;18:766-73 pubmed publisher
    ..has a major role in cardiac adaptive responses, as exemplified by the isoform switch of the sarcomeric protein titin, which adjusts ventricular filling...
  3. Lee E, Gao M, Pinotsis N, Wilmanns M, Schulten K. Mechanical strength of the titin Z1Z2-telethonin complex. Structure. 2006;14:497-509 pubmed
    Using molecular dynamics simulations, we have explored the mechanical strength of the titin Z1Z2-telethonin complex, namely, its ability to bear strong forces such as those encountered during passive muscle stretch...
  4. Lange S, Auerbach D, McLoughlin P, Perriard E, Schafer B, Perriard J, et al. Subcellular targeting of metabolic enzymes to titin in heart muscle may be mediated by DRAL/FHL-2. J Cell Sci. 2002;115:4925-36 pubmed
    ..enzymes creatine kinase, adenylate kinase and phosphofructokinase by interaction with the elastic filament protein titin in cardiomyocytes...
  5. Labeit S, Gautel M, Lakey A, Trinick J. Towards a molecular understanding of titin. EMBO J. 1992;11:1711-6 pubmed
    b>Titin is at present the largest known protein (M(r) 3000 kDa) and its expression is restricted to vertebrate striated muscle. Single molecules span from M- to Z-lines and therefore over 1 micron...
  6. Makarenko I, Opitz C, Leake M, Neagoe C, Kulke M, Gwathmey J, et al. Passive stiffness changes caused by upregulation of compliant titin isoforms in human dilated cardiomyopathy hearts. Circ Res. 2004;95:708-16 pubmed
    ..In this study, we analyzed titin expression in left ventricles of 19 control human donors and 9 severely diseased (nonischemic) dilated ..
  7. Nagy A, Cacciafesta P, Grama L, Kengyel A, Málnási Csizmadia A, Kellermayer M. Differential actin binding along the PEVK domain of skeletal muscle titin. J Cell Sci. 2004;117:5781-9 pubmed
    Parts of the PEVK (Pro-Glu-Val-Lys) domain of the skeletal muscle isoform of the giant intrasarcomeric protein titin have been shown to bind F-actin. However, the mechanisms and physiological function of this are poorly understood...
  8. Zou P, Pinotsis N, Lange S, Song Y, Popov A, Mavridis I, et al. Palindromic assembly of the giant muscle protein titin in the sarcomeric Z-disk. Nature. 2006;439:229-33 pubmed
    ..using X-ray crystallography, how the amino terminus of the longest filament component, the giant muscle protein titin, is assembled into an antiparallel (2:1) sandwich complex by the Z-disk ligand telethonin...
  9. Muhle Goll C, Habeck M, Cazorla O, Nilges M, Labeit S, Granzier H. Structural and functional studies of titin's fn3 modules reveal conserved surface patterns and binding to myosin S1--a possible role in the Frank-Starling mechanism of the heart. J Mol Biol. 2001;313:431-47 pubmed
    The A-band part of titin, a striated-muscle specific protein spanning from the Z-line to the M-line, mainly consists of a well-ordered super-repeat array of immunoglobulin-like and fibronectin-type III (fn3)-like domains...
  10. Mrosek M, Labeit D, Witt S, Heerklotz H, von Castelmur E, Labeit S, et al. Molecular determinants for the recruitment of the ubiquitin-ligase MuRF-1 onto M-line titin. FASEB J. 2007;21:1383-92 pubmed
    b>Titin forms an intrasarcomeric filament system in vertebrate striated muscle, which has elastic and signaling properties and is thereby central to mechanotransduction...
  11. Hidalgo C, Hudson B, Bogomolovas J, Zhu Y, Anderson B, Greaser M, et al. PKC phosphorylation of titin's PEVK element: a novel and conserved pathway for modulating myocardial stiffness. Circ Res. 2009;105:631-8, 17 p following 638 pubmed publisher
    ..Myocardial sarcomeres also contain a third myofilament, titin, and it is unknown whether titin can be phosphorylated by PKC and whether it affects passive tension...
  12. Laure L, Daniele N, Suel L, Marchand S, Aubert S, Bourg N, et al. A new pathway encompassing calpain 3 and its newly identified substrate cardiac ankyrin repeat protein is involved in the regulation of the nuclear factor-?B pathway in skeletal muscle. FEBS J. 2010;277:4322-37 pubmed publisher
    ..CARP), and the calpain 3 protease was identified in the N2A elastic region of the giant sarcomeric protein titin. The present study aimed to investigate the function(s) of this complex in the skeletal muscle...
  13. Gautel M, Lakey A, Barlow D, Holmes Z, Scales S, Leonard K, et al. Titin antibodies in myasthenia gravis: identification of a major immunogenic region of titin. Neurology. 1993;43:1581-5 pubmed
    ..Analysis of the isolated cDNAs show that all share a common sequence encoding a distinct region of the titin gene...
  14. Houmeida A, Holt J, Tskhovrebova L, Trinick J. Studies of the interaction between titin and myosin. J Cell Biol. 1995;131:1471-81 pubmed
    The interaction of titin with myosin has been studied by binding assays and electron microscopy. Electron micrographs of the titin-myosin complex suggest a binding site near the tip of the tail of the myosin molecule...
  15. Young P, Ferguson C, Banuelos S, Gautel M. Molecular structure of the sarcomeric Z-disk: two types of titin interactions lead to an asymmetrical sorting of alpha-actinin. EMBO J. 1998;17:1614-24 pubmed
    The sarcomeric Z-disk, the anchoring plane of thin (actin) filaments, links titin (also called connectin) and actin filaments from opposing sarcomere halves in a lattice connected by alpha-actinin...
  16. Goll C, Pastore A, Nilges M. The three-dimensional structure of a type I module from titin: a prototype of intracellular fibronectin type III domains. Structure. 1998;6:1291-302 pubmed
    b>Titin is a huge protein ( approximately 3 MDa) that is present in the contractile unit (sarcomere) of striated muscle and has a key role in muscle assembly and elasticity. Titin is mainly composed of two types of module (type I and II)...
  17. Nagueh S, Shah G, Wu Y, Torre Amione G, King N, Lahmers S, et al. Altered titin expression, myocardial stiffness, and left ventricular function in patients with dilated cardiomyopathy. Circulation. 2004;110:155-62 pubmed
    The role of the giant protein titin in patients with heart failure is not well established...
  18. Musco G, Tziatzios C, Schuck P, Pastore A. Dissecting titin into its structural motifs: identification of an alpha-helix motif near the titin N-terminus. Biochemistry. 1995;34:553-61 pubmed
    Titin, also known as connectin, is a giant modular protein specifically found in vertebrate striated muscle...
  19. Eilertsen K, Kazmierski S, Keller T. Cellular titin localization in stress fibers and interaction with myosin II filaments in vitro. J Cell Biol. 1994;126:1201-10 pubmed
    We previously discovered a cellular isoform of titin (originally named T-protein) colocalized with myosin II in the terminal web domain of the chicken intestinal epithelial cell brush border cytoskeleton (Eilertsen, K.J., and T.C.S...
  20. von Castelmur E, Marino M, Svergun D, Kreplak L, Ucurum Fotiadis Z, Konarev P, et al. A regular pattern of Ig super-motifs defines segmental flexibility as the elastic mechanism of the titin chain. Proc Natl Acad Sci U S A. 2008;105:1186-91 pubmed publisher
    Myofibril elasticity, critical to muscle function, is dictated by the intrasarcomeric filament titin, which acts as a molecular spring...
  21. Müller S, Lange S, Gautel M, Wilmanns M. Rigid conformation of an immunoglobulin domain tandem repeat in the A-band of the elastic muscle protein titin. J Mol Biol. 2007;371:469-80 pubmed
    Most of the structure of the giant muscle protein titin is formed by small modular domains. Many of them are predicted to be arranged in repeats with short linkers that may be key determinants of the peculiar elastic properties of titin...
  22. Lee E, Hsin J, Mayans O, Schulten K. Secondary and tertiary structure elasticity of titin Z1Z2 and a titin chain model. Biophys J. 2007;93:1719-35 pubmed
    The giant protein titin, which is responsible for passive elasticity in muscle fibers, is built from approximately 300 regular immunoglobulin-like (Ig) domains and FN-III repeats...
  23. Gregorio C, Trombitas K, Centner T, Kolmerer B, Stier G, Kunke K, et al. The NH2 terminus of titin spans the Z-disc: its interaction with a novel 19-kD ligand (T-cap) is required for sarcomeric integrity. J Cell Biol. 1998;143:1013-27 pubmed
    b>Titin is a giant elastic protein in vertebrate striated muscles with an unprecedented molecular mass of 3-4 megadaltons. Single molecules of titin extend from the Z-line to the M-line...
  24. Cazorla O, Freiburg A, Helmes M, Centner T, McNabb M, Wu Y, et al. Differential expression of cardiac titin isoforms and modulation of cellular stiffness. Circ Res. 2000;86:59-67 pubmed
    Extension of the I-band segment of titin gives rise to part of the diastolic force of cardiac muscle...
  25. Freiburg A, Trombitas K, Hell W, Cazorla O, Fougerousse F, Centner T, et al. Series of exon-skipping events in the elastic spring region of titin as the structural basis for myofibrillar elastic diversity. Circ Res. 2000;86:1114-21 pubmed
    Titins are megadalton-sized filamentous polypeptides of vertebrate striated muscle. The I-band region of titin underlies the myofibrillar passive tension response to stretch...
  26. Ottenheijm C, Voermans N, Hudson B, Irving T, Stienen G, van Engelen B, et al. Titin-based stiffening of muscle fibers in Ehlers-Danlos Syndrome. J Appl Physiol (1985). 2012;112:1157-65 pubmed publisher
    ..EDS patients, intracellular adaptations take place in the elastic properties of the giant muscle protein titin. we performed extensive single muscle fiber mechanical studies to determine active and passive properties in TNX-..
  27. Gerull B, Gramlich M, Atherton J, McNabb M, Trombitas K, Sasse Klaassen S, et al. Mutations of TTN, encoding the giant muscle filament titin, cause familial dilated cardiomyopathy. Nat Genet. 2002;30:201-4 pubmed
    ..in the gene encoding giant-muscle filament titin (TTN) cause autosomal dominant DCM linked to chromosome 2q31 (CMD1G; MIM 604145)...
  28. Li H, Linke W, Oberhauser A, Carrion Vazquez M, Kerkvliet J, Lu H, et al. Reverse engineering of the giant muscle protein titin. Nature. 2002;418:998-1002 pubmed
    ..The protein titin provides muscle with its passive elasticity...
  29. Freiburg A, Gautel M. A molecular map of the interactions between titin and myosin-binding protein C. Implications for sarcomeric assembly in familial hypertrophic cardiomyopathy. Eur J Biochem. 1996;235:317-23 pubmed
    ..proteins is believed to be due partly to their interaction with the giant muscle protein titin (also called connectin), which spans the entire sarcomere and may act as a molecular ruler...
  30. Puchner E, Alexandrovich A, Kho A, Hensen U, Schäfer L, Brandmeier B, et al. Mechanoenzymatics of titin kinase. Proc Natl Acad Sci U S A. 2008;105:13385-90 pubmed publisher
    ..In vertebrate muscle, the giant elastic protein titin is involved in strain sensing via its C-terminal kinase domain (TK) at the sarcomeric M-band and contributes to ..
  31. Centner T, Yano J, Kimura E, McElhinny A, Pelin K, Witt C, et al. Identification of muscle specific ring finger proteins as potential regulators of the titin kinase domain. J Mol Biol. 2001;306:717-26 pubmed
    The giant myofibrillar protein titin contains within its C-terminal region a serine-threonine kinase of unknown function...
  32. Bang M, Centner T, Fornoff F, Geach A, Gotthardt M, McNabb M, et al. The complete gene sequence of titin, expression of an unusual approximately 700-kDa titin isoform, and its interaction with obscurin identify a novel Z-line to I-band linking system. Circ Res. 2001;89:1065-72 pubmed
    b>Titin is a giant vertebrate striated muscle protein with critical importance for myofibril elasticity and structural integrity...
  33. Nicolao P, Xiang F, Gunnarsson L, Giometto B, Edstrom L, Anvret M, et al. Autosomal dominant myopathy with proximal weakness and early respiratory muscle involvement maps to chromosome 2q. Am J Hum Genet. 1999;64:788-92 pubmed
    ..The affected individuals from these two families share an identical haplotype, which suggests a common origin. ..
  34. Pfuhl M, Pastore A. Tertiary structure of an immunoglobulin-like domain from the giant muscle protein titin: a new member of the I set. Structure. 1995;3:391-401 pubmed
    b>Titin is a gigantic protein located in the thick filament of vertebrate muscles. The putative functions of titin range from interactions with myosin and other muscle proteins to a role in muscle recoil...
  35. Kolmerer B, Olivieri N, Witt C, Herrmann B, Labeit S. Genomic organization of M line titin and its tissue-specific expression in two distinct isoforms. J Mol Biol. 1996;256:556-63 pubmed
    b>Titin is a 3000 kDa large protein of vertebrate striated muscle which extends from Z discs to M lines...
  36. Ohlsson M, Hedberg C, Brådvik B, Lindberg C, Tajsharghi H, Danielsson O, et al. Hereditary myopathy with early respiratory failure associated with a mutation in A-band titin. Brain. 2012;135:1682-94 pubmed publisher
    ..274375T>C; p.Cys30071Arg, in the titin gene (TTN)...
  37. Nagy A, Grama L, Huber T, Bianco P, Trombitas K, Granzier H, et al. Hierarchical extensibility in the PEVK domain of skeletal-muscle titin. Biophys J. 2005;89:329-36 pubmed
    b>Titin is the main determinant of passive muscle force. Physiological extension of titin derives largely from its PEVK (Pro-Glu-Val-Lys) domain, which has a different length in different muscle types...
  38. Lange S, Xiang F, Yakovenko A, Vihola A, Hackman P, Rostkova E, et al. The kinase domain of titin controls muscle gene expression and protein turnover. Science. 2005;308:1599-603 pubmed
    The giant sarcomeric protein titin contains a protein kinase domain (TK) ideally positioned to sense mechanical load...
  39. Labeit S, Kolmerer B. Titins: giant proteins in charge of muscle ultrastructure and elasticity. Science. 1995;270:293-6 pubmed
    ..thick and thin filaments, vertebrate striated muscle contains a third filament system formed by the giant protein titin. Single titin molecules extend from Z discs to M lines and are longer than 1 micrometer...
  40. Trinick J, Tskhovrebova L. Titin: a molecular control freak. Trends Cell Biol. 1999;9:377-80 pubmed
    Recent studies of the giant protein titin have shed light on its roles in muscle assembly and elasticity and include the surprising findings described here...
  41. Mues A, van der Ven P, Young P, Fürst D, Gautel M. Two immunoglobulin-like domains of the Z-disc portion of titin interact in a conformation-dependent way with telethonin. FEBS Lett. 1998;428:111-4 pubmed
    The giant muscle protein titin/connectin plays a crucial role in myofibrillogenesis as a molecular ruler for sarcomeric protein sorting...
  42. Knoll R, Hoshijima M, Hoffman H, Person V, Lorenzen Schmidt I, Bang M, et al. The cardiac mechanical stretch sensor machinery involves a Z disc complex that is defective in a subset of human dilated cardiomyopathy. Cell. 2002;111:943-55 pubmed
    ..MLP interacts with and colocalizes with telethonin (T-cap), a titin interacting protein...
  43. Hackman P, Vihola A, Haravuori H, Marchand S, Sarparanta J, De Seze J, et al. Tibial muscular dystrophy is a titinopathy caused by mutations in TTN, the gene encoding the giant skeletal-muscle protein titin. Am J Hum Genet. 2002;71:492-500 pubmed
    ..The linked region includes the giant TTN gene, which encodes the central sarcomeric protein, titin. We have previously shown a secondary calpain-3 defect to be associated with TMD, which further underscored that ..
  44. Izumi R, Niihori T, Aoki Y, Suzuki N, Kato M, Warita H, et al. Exome sequencing identifies a novel TTN mutation in a family with hereditary myopathy with early respiratory failure. J Hum Genet. 2013;58:259-66 pubmed publisher
    ..groups reported three mutations in TTN in patients with hereditary myopathy with early respiratory failure (HMERF, MIM #603689), which is characterized by overlapping pathologic findings with MFMs...
  45. Taylor M, Graw S, Sinagra G, Barnes C, Slavov D, Brun F, et al. Genetic variation in titin in arrhythmogenic right ventricular cardiomyopathy-overlap syndromes. Circulation. 2011;124:876-85 pubmed publisher
    ..We evaluated the cardiomyopathy gene titin (TTN) as a candidate ARVC gene because of its proximity to an ARVC locus at position 2q32 and the connection of ..
  46. Pfeffer G, Elliott H, Griffin H, Barresi R, Miller J, Marsh J, et al. Titin mutation segregates with hereditary myopathy with early respiratory failure. Brain. 2012;135:1695-713 pubmed publisher
    ..A combination of genome-wide linkage and whole exome sequencing revealed the likely causal genetic variant in the titin (TTN) gene (g.274375T>C; p.Cys30071Arg) within a shared haplotype of 2.93 Mbp on chromosome 2...
  47. Zou P, Gautel M, Geerlof A, Wilmanns M, Koch M, Svergun D. Solution scattering suggests cross-linking function of telethonin in the complex with titin. J Biol Chem. 2003;278:2636-44 pubmed
    Telethonin interacts specifically with the two Z-disk IG-like domains (Z1Z2) at the N terminus of titin, the largest presently known protein...
  48. Ali M, Cho W, Hudson B, Kassiri Z, Granzier H, Schulz R. Titin is a target of matrix metalloproteinase-2: implications in myocardial ischemia/reperfusion injury. Circulation. 2010;122:2039-47 pubmed publisher
    b>Titin is the largest mammalian (?3000 to 4000 kDa) and myofilament protein that acts as a molecular spring in the cardiac sarcomere and determines systolic and diastolic function...
  49. Carmignac V, Salih M, Quijano Roy S, Marchand S, Al Rayess M, Mukhtar M, et al. C-terminal titin deletions cause a novel early-onset myopathy with fatal cardiomyopathy. Ann Neurol. 2007;61:340-51 pubmed
    The giant protein titin is essential for striated muscle development, structure, and elasticity. All titin mutations reported to date cause late-onset, dominant disorders involving either skeletal muscle or the heart...
  50. Kulke M, Fujita Becker S, Rostkova E, Neagoe C, Labeit D, Manstein D, et al. Interaction between PEVK-titin and actin filaments: origin of a viscous force component in cardiac myofibrils. Circ Res. 2001;89:874-81 pubmed
    The giant muscle protein titin contains a unique sequence, the PEVK domain, the elastic properties of which contribute to the mechanical behavior of relaxed cardiomyocytes...
  51. Linke W, Ivemeyer M, Labeit S, Hinssen H, Ruegg J, Gautel M. Actin-titin interaction in cardiac myofibrils: probing a physiological role. Biophys J. 1997;73:905-19 pubmed
    The high stiffness of relaxed cardiac myofibrils is explainable mainly by the expression of a short-length titin (connectin), the giant elastic protein of the vertebrate myofibrillar cytoskeleton...
  52. Kinbara K, Sorimachi H, Ishiura S, Suzuki K. Muscle-specific calpain, p94, interacts with the extreme C-terminal region of connectin, a unique region flanked by two immunoglobulin C2 motifs. Arch Biochem Biophys. 1997;342:99-107 pubmed
    ..two-hybrid system, we have recently reported that skeletal muscle-specific calpain, p94, binds specifically to connectin (or titin), a gigantic muscle elastic protein...
  53. Gautel M, Goulding D, Bullard B, Weber K, Fürst D. The central Z-disk region of titin is assembled from a novel repeat in variable copy numbers. J Cell Sci. 1996;109 ( Pt 11):2747-54 pubmed
    The giant sarcomeric protein titin (also described as connectin) is composed mainly of immunoglobulin (Ig)-like and fibronectin type III (fn3)-like domains arranged consecutively...
  54. Labeit S, Barlow D, Gautel M, Gibson T, Holt J, Hsieh C, et al. A regular pattern of two types of 100-residue motif in the sequence of titin. Nature. 1990;345:273-6 pubmed
    b>Titin is the largest polypeptide yet described (relative molecular mass approximately 3 x 10(6); refs 1, 2) and an abundant protein of striated muscle. Its molecules are string-like and in vivo span from the M to Z-lines...