Telethonin is a 19.0 kDa protein composed of 167 amino acids.[8]Telethonin has a unique β-sheet structure, which enables antiparallel association with theTitin Z1-Z2 domains incardiac andskeletal muscle.[9] Structural analysis of full-length Telethonin with theN-terminal region ofTitin indicate that theC-terminus of Telethonin is critical for the dimerization of two Telethonin/Titin complexes into a higher oligomeric structure.[10]
Telethonin expression is developmentally regulated in bothcardiac andskeletal muscle and is thought to be critical to sarcomere assembly.[11] Telethonin was found to be a late assembling protein only present in maturemyofibrils atZ-discs.[12]
Telethonin forms a complex withmuscle LIM protein (MLP) atsarcomere Z-discs, which constitutes part of thecardiomyocyte stretch sensory mechanism.[13] It has also been shown that Telethonin binds to the beta-subunit of the slow activating component of thedelayed rectifier potassium channel, MinK, in areas localized toT-tubule membranes surroundingZ-lines in the innermyocardium.[14] In addition, Telethonin interacts with the sodium channelNa(v)1.5, and alters the activation kinetics via doubling the window current.[15] These data suggest that Telethonin may constitute a mechano-electrical links betweenZ-lines andT-tubules. Further functional evidence for this has come from studies utilizing a Telethonin-knockout mouse (KO), which have shown that Telethonin is involved inT-tubule structure and function, as well as apoptosis in the heart. Telethonin KO animals showed preservedTitin anchoring at baseline, and instead showed a profound deficit duringnuclear biomechanical stress in modulating the turnover of the proapoptoticp53 protein.[16] Telethonin KO animals also displayedcalcium transient dysynchrony,T-tubule loss and depressedL-type calcium channel function.[17]
The intracellular degradation of Telethonin is regulated byMDM2 in aproteasomal-dependent yetubiquitin-independent manner.[21] Telethonin specifically interacts with the pro-apoptotic proteinSiva, suggesting that Telethonin may be involved in the mechanism underlyingCoxsackievirus B3 infection in acute and chronicmyocarditis[22]
Telethonin was also identified to be targeted and regulated by transcriptional activatorsCLOCK andBMAL1, thus demonstrating thatTCAP is a circadian regulated gene.[23]
^Pinotsis N, Petoukhov M, Lange S, Svergun D, Zou P, Gautel M, Wilmanns M (Aug 2006). "Evidence for a dimeric assembly of two titin/telethonin complexes induced by the telethonin C-terminus".Journal of Structural Biology.155 (2):239–50.doi:10.1016/j.jsb.2006.03.028.PMID16713295.
^Mason P, Bayol S, Loughna PT (Apr 1999). "The novel sarcomeric protein telethonin exhibits developmental and functional regulation".Biochemical and Biophysical Research Communications.257 (3):699–703.doi:10.1006/bbrc.1999.0531.PMID10208846.
^abFurukawa T, Ono Y, Tsuchiya H, Katayama Y, Bang ML, Labeit D, Labeit S, Inagaki N, Gregorio CC (Nov 2001). "Specific interaction of the potassium channel beta-subunit minK with the sarcomeric protein T-cap suggests a T-tubule-myofibril linking system".Journal of Molecular Biology.313 (4):775–84.doi:10.1006/jmbi.2001.5053.PMID11697903.
^abMayans O, van der Ven PF, Wilm M, Mues A, Young P, Fürst DO, Wilmanns M, Gautel M (Oct 1998). "Structural basis for activation of the titin kinase domain during myofibrillogenesis".Nature.395 (6705):863–9.Bibcode:1998Natur.395..863M.doi:10.1038/27603.PMID9804419.S2CID4426977.
^Tian LF, Li HY, Jin BF, Pan X, Man JH, Zhang PJ, Li WH, Liang B, Liu H, Zhao J, Gong WL, Zhou T, Zhang XM (Jun 2006). "MDM2 interacts with and downregulates a sarcomeric protein, TCAP".Biochemical and Biophysical Research Communications.345 (1):355–61.doi:10.1016/j.bbrc.2006.04.108.PMID16678796..
^Andersen PS, Havndrup O, Hougs L, Sørensen KM, Jensen M, Larsen LA, Hedley P, Thomsen AR, Moolman-Smook J, Christiansen M, Bundgaard H (Mar 2009). "Diagnostic yield, interpretation, and clinical utility of mutation screening of sarcomere encoding genes in Danish hypertrophic cardiomyopathy patients and relatives".Human Mutation.30 (3):363–70.doi:10.1002/humu.20862.PMID19035361.S2CID30898294.
^Itoh-Satoh M, Hayashi T, Nishi H, Koga Y, Arimura T, Koyanagi T, Takahashi M, Hohda S, Ueda K, Nouchi T, Hiroe M, Marumo F, Imaizumi T, Yasunami M, Kimura A (Feb 2002). "Titin mutations as the molecular basis for dilated cardiomyopathy".Biochemical and Biophysical Research Communications.291 (2):385–93.doi:10.1006/bbrc.2002.6448.PMID11846417.S2CID1824336.
^Nakano N, Hori H, Abe M, Shibata H, Arimura T, Sasaoka T, Sawabe M, Chida K, Arai T, Nakahara K, Kubo T, Sugimoto K, Katsuya T, Ogihara T, Doi Y, Izumi T, Kimura A (Dec 2007). "Interaction of BMP10 with Tcap may modulate the course of hypertensive cardiac hypertrophy".American Journal of Physiology. Heart and Circulatory Physiology.293 (6): H3396–403.doi:10.1152/ajpheart.00311.2007.PMID17921333.S2CID45084505.
^Kojic S, Medeot E, Guccione E, Krmac H, Zara I, Martinelli V, Valle G, Faulkner G (May 2004). "The Ankrd2 protein, a link between the sarcomere and the nucleus in skeletal muscle".Journal of Molecular Biology.339 (2):313–25.doi:10.1016/j.jmb.2004.03.071.PMID15136035.
^Nakano N, Hori H, Abe M, Shibata H, Arimura T, Sasaoka T, Sawabe M, Chida K, Arai T, Nakahara K, Kubo T, Sugimoto K, Katsuya T, Ogihara T, Doi Y, Izumi T, Kimura A (Dec 2007). "Interaction of BMP10 with Tcap may modulate the course of hypertensive cardiac hypertrophy".American Journal of Physiology. Heart and Circulatory Physiology.293 (6): H3396–403.doi:10.1152/ajpheart.00311.2007.PMID17921333.S2CID45084505.
^Tian LF, Li HY, Jin BF, Pan X, Man JH, Zhang PJ, Li WH, Liang B, Liu H, Zhao J, Gong WL, Zhou T, Zhang XM (Jun 2006). "MDM2 interacts with and downregulates a sarcomeric protein, TCAP".Biochemical and Biophysical Research Communications.345 (1):355–61.doi:10.1016/j.bbrc.2006.04.108.PMID16678796.
Mayans O, van der Ven PF, Wilm M, Mues A, Young P, Fürst DO, Wilmanns M, Gautel M (Oct 1998). "Structural basis for activation of the titin kinase domain during myofibrillogenesis".Nature.395 (6705):863–9.Bibcode:1998Natur.395..863M.doi:10.1038/27603.PMID9804419.S2CID4426977.
Moreira ES, Wiltshire TJ, Faulkner G, Nilforoushan A, Vainzof M, Suzuki OT, Valle G, Reeves R, Zatz M, Passos-Bueno MR, Jenne DE (Feb 2000). "Limb-girdle muscular dystrophy type 2G is caused by mutations in the gene encoding the sarcomeric protein telethonin".Nature Genetics.24 (2):163–6.doi:10.1038/72822.PMID10655062.S2CID8698402.
Schröder R, Reimann J, Iakovenko A, Mues A, Bönnemann CG, Matten J, Gautel M (2002). "Early and selective disappearance of telethonin protein from the sarcomere in neurogenic atrophy".Journal of Muscle Research and Cell Motility.22 (3):259–64.doi:10.1023/A:1012242011109.PMID11763198.S2CID22553971.
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Kojic S, Medeot E, Guccione E, Krmac H, Zara I, Martinelli V, Valle G, Faulkner G (May 2004). "The Ankrd2 protein, a link between the sarcomere and the nucleus in skeletal muscle".Journal of Molecular Biology.339 (2):313–25.doi:10.1016/j.jmb.2004.03.071.PMID15136035.