MYH7

MYH7
Available structures
PDB	Ortholog search: PDBe RCSB
List of PDB id codes
	3DTP, 4DB1, 4P7H, 4XA1, 4XA3, 4XA4, 4XA6, 4PA0, 5CHX, 5CJ0, 5CJ4, 5CJ1, 2FXO, 2FXM
Identifiers
Aliases	MYH7, CMD1S, CMH1, MPD1, MYHCB, SPMD, SPMM, myosin, heavy chain 7, cardiac muscle, beta, myosin heavy chain 7
External IDs	OMIM: 160760; MGI: 2155600; HomoloGene: 68044; GeneCards: MYH7; OMA:MYH7 - orthologs
Gene location (Human)
Chr.	Chromosome 14 (human)
End	23,435,660 bp
Gene location (Mouse)
Chr.	Chromosome 14 (mouse)
End	55,232,083 bp
RNA expression pattern
	Top expressed in
	apex of heart; ; muscle of thigh; ; Skeletal muscle tissue of biceps brachii; ; gastrocnemius muscle; ; right ventricle; ; left ventricle; ; glutes; ; triceps brachii muscle; ; myocardium of left ventricle; ; vastus lateralis muscle;
	Top expressed in
	soleus muscle; ; atrioventricular valve; ; endocardial cushion; ; ankle; ; plantaris muscle; ; cardiac muscle tissue of left ventricle; ; extraocular muscle; ; thoracic diaphragm; ; intercostal muscle; ; internal carotid artery;
	More reference expression data
	; ;
	More reference expression data
Gene ontology
Molecular function	nucleotide binding; calmodulin binding; protein binding; actin binding; cytoskeletal motor activity; ATP binding; ATPase activity; microfilament motor activity; actin filament binding; microtubule motor activity; microtubule binding;
Cellular component	cytoplasm; stress fiber; Z discdkac; myosin filament; myosin complex; muscle myosin complex; myofibril; sarcomere;
Biological process	cardiac muscle contraction; adult heart development; transition between fast and slow fiber; regulation of the force of heart contraction; skeletal muscle contraction; regulation of slow-twitch skeletal muscle fiber contraction; regulation of heart rate; ventricular cardiac muscle tissue morphogenesis; ATP metabolic process; muscle filament sliding; striated muscle contraction; regulation of the force of skeletal muscle contraction; muscle contraction; cardiac muscle hypertrophy in response to stress; microtubule-based movement;
	Sources:Amigo / QuickGO
Orthologs
	4625
	140781
	ENSG00000092054
	ENSMUSG00000053093
	P12883
	Q91Z83
	NM_000257
	NM_080728; NM_001361607
	NP_000248
	NP_542766; NP_001348536
	Wikidata
View/Edit Human	View/Edit Mouse

MYH7 is a gene encoding a myosin heavy chain beta (MHC-β) isoform (slow twitch) expressed primarily in the heart, but also in skeletal muscles (type I fibers).^[5] This isoform is distinct from the fast isoform of cardiac myosin heavy chain, MYH6, referred to as MHC-α. MHC-β is the major protein comprising the thick filament that forms the sarcomeres in cardiac muscle and plays a major role in cardiac muscle contraction.^[6]

Structure

MHC-β is a 223 kDa protein composed of 1935 amino acids.^[7]^[8] MHC-β is a hexameric, asymmetric motor forming the bulk of the thick filament in cardiac muscle. MHC-β is composed of N-terminal globular heads (20 nm) that project laterally, and alpha helical tails (130 nm) that dimerize and multimerize into a coiled-coil motif to form the light meromyosin (LMM), thick filament rod.^[9] The 9 nm alpha-helical neck region of each MHC-β head non-covalently binds two light chains, essential light chain (MYL3) and regulatory light chain (MYL2).^[10] Approximately 300 myosin molecules constitute one thick filament.^[11] There are two isoforms of cardiac MHC, α and β, which display 93% homology. MHC-α and MHC-β display significantly different enzymatic properties, with α having 150-300% the contractile velocity and 60-70% actin attachment time as that of β.^[12]^[13] MHC-β is predominately expressed in the human ventricle, while MHC-α is predominantly expressed in human atria.^{[citation needed]}

Function

It is the enzymatic activity of the ATPase in the myosin head that cyclically hydrolyzes ATP, fueling the myosin power stroke. This process converts chemical to mechanical energy, and propels shortening of the sarcomeres in order to generate intraventricular pressure and power. An accepted mechanism for this process is that ADP-bound myosin attaches to actin while thrusting tropomyosin inwards,^[14] then the S1-S2 myosin lever arm rotates ~70° about the converter domain and drives actin filaments towards the M-line.^[15]

Clinical significance

Several mutations in MYH7 have been associated with inherited cardiomyopathies. Lowrance et al. were the first to identify the causative mutation Arg403Gln for hypertrophic cardiomyopathy (HCM) in the MYH7 gene.^[16] Studies have since identified several more MYH7 mutations, that are estimated to be causal in approximately 40% of HCM cases. This condition is an autosomal-dominant disease, in which a single copy of the variant gene causes enlargement of the left ventricle of the heart. Disease onset usually occurs later in life, perhaps triggered by changes in thyroid hormone function and/or physical stress.

Another condition associated to mutations in this gene is paraspinal and proximal muscle atrophy.^[17]

A myopathy caused by a MYH7 mutation in pigs.

References

^ ^a ^b ^c GRCh38: Ensembl release 89: ENSG00000092054 – Ensembl, May 2017
^ ^a ^b ^c GRCm38: Ensembl release 89: ENSMUSG00000053093 – Ensembl, May 2017
^ "Human PubMed Reference:". National Center for Biotechnology Information, U.S. National Library of Medicine.
^ "Mouse PubMed Reference:". National Center for Biotechnology Information, U.S. National Library of Medicine.
^ Quiat D, Voelker KA, Pei J, Grishin NV, Grange RW, Bassel-Duby R, et al. (June 2011). "Concerted regulation of myofiber-specific gene expression and muscle performance by the transcriptional repressor Sox6". Proceedings of the National Academy of Sciences of the United States of America. 108 (25): 10196–10201. Bibcode:2011PNAS..10810196Q. doi:10.1073/pnas.1107413108. PMC 3121857. PMID 21633012.
^ Wang L, Geist J, Grogan A, Hu LR, Kontrogianni-Konstantopoulos A (March 2018). "Thick Filament Protein Network, Functions, and Disease Association". Comprehensive Physiology. 8 (2): 631–709. doi:10.1002/cphy.c170023. ISBN 9780470650714. PMC 6404781. PMID 29687901.
^ "Cardiac Organellar Protein Atlas Knowledgebase (COPaKB)". heartproteome.org. Archived from the original on 4 March 2016. Retrieved 14 October 2015.
^ Zong NC, Li H, Li H, Lam MP, Jimenez RC, Kim CS, et al. (October 2013). "Integration of cardiac proteome biology and medicine by a specialized knowledgebase". Circulation Research. 113 (9): 1043–1053. doi:10.1161/CIRCRESAHA.113.301151. PMC 4076475. PMID 23965338.
^ Tamborrini D, Wang Z, Wagner T, Tacke S, Stabrin M, Grange M, et al. (November 2023). "Structure of the native myosin filament in the relaxed cardiac sarcomere". Nature. 623 (7988): 863–871. Bibcode:2023Natur.623..863T. doi:10.1038/s41586-023-06690-5. PMC 10665186. PMID 37914933.
^ Palmer BM (September 2005). "Thick filament proteins and performance in human heart failure". Heart Failure Reviews. 10 (3): 187–197. doi:10.1007/s10741-005-5249-1. PMID 16416042. S2CID 20691228.
^ Harris SP, Lyons RG, Bezold KL (March 2011). "In the thick of it: HCM-causing mutations in myosin binding proteins of the thick filament". Circulation Research. 108 (6): 751–764. doi:10.1161/CIRCRESAHA.110.231670. PMC 3076008. PMID 21415409.
^ Palmer BM (September 2005). "Thick filament proteins and performance in human heart failure". Heart Failure Reviews. 10 (3): 187–197. doi:10.1007/s10741-005-5249-1. PMID 16416042. S2CID 20691228.
^ Alpert NR, Brosseau C, Federico A, Krenz M, Robbins J, Warshaw DM (October 2002). "Molecular mechanics of mouse cardiac myosin isoforms". American Journal of Physiology. Heart and Circulatory Physiology. 283 (4): H1446–H1454. doi:10.1152/ajpheart.00274.2002. PMID 12234796.
^ McKillop DF, Geeves MA (August 1993). "Regulation of the interaction between actin and myosin subfragment 1: evidence for three states of the thin filament". Biophysical Journal. 65 (2): 693–701. Bibcode:1993BpJ....65..693M. doi:10.1016/S0006-3495(93)81110-X. PMC 1225772. PMID 8218897.
^ Tyska MJ, Warshaw DM (January 2002). "The myosin power stroke". Cell Motility and the Cytoskeleton. 51 (1): 1–15. doi:10.1002/cm.10014. PMID 11810692.
^ Geisterfer-Lowrance AA, Kass S, Tanigawa G, Vosberg HP, McKenna W, Seidman CE, et al. (September 1990). "A molecular basis for familial hypertrophic cardiomyopathy: a beta cardiac myosin heavy chain gene missense mutation". Cell. 62 (5): 999–1006. doi:10.1016/0092-8674(90)90274-i. PMID 1975517. S2CID 45182243.
^ Park JM, Kim YJ, Yoo JH, Hong YB, Park JH, Koo H, et al. (July 2013). "A novel MYH7 mutation with prominent paraspinal and proximal muscle involvement". Neuromuscular Disorders. 23 (7): 580–586. doi:10.1016/j.nmd.2013.04.003. PMID 23707328. S2CID 6194064.