MYH7

From Wikipedia, the free encyclopedia
Jump to: navigation, search
Myosin, heavy chain 7, cardiac muscle, beta
PBB Protein MYH7 image.jpg
PDB rendering based on 2fxm.
Available structures
PDB Ortholog search: PDBe, RCSB
Identifiers
Symbols MYH7 ; CMD1S; CMH1; MPD1; MYHCB; SPMD; SPMM
External IDs OMIM160760 MGI2155600 HomoloGene68044 GeneCards: MYH7 Gene
RNA expression pattern
PBB GE MYH7 204737 s at tn.png
PBB GE MYH7 216265 x at tn.png
More reference expression data
Orthologs
Species Human Mouse
Entrez 4625 140781
Ensembl ENSG00000092054 ENSMUSG00000053093
UniProt P12883 Q91Z83
RefSeq (mRNA) NM_000257 NM_080728
RefSeq (protein) NP_000248 NP_542766
Location (UCSC) Chr 14:
23.41 – 23.44 Mb
Chr 14:
54.97 – 54.99 Mb
PubMed search [1] [2]

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).[1] 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 in cardiac muscle and plays a major role in cardiac muscle contraction.

Structure[edit]

MHC-β is a 223 kDa protein composed of 1935 amino acids.[2][3] MHC-β is a hexameric, asymmetric motor forming the bulk of the thick filament in cardiac muscle. MHC-β is composed of N-termimal 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. 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).[4] Approximately 300 myosin molecules constitute one thick filament.[5] 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.[6][7] MHC-β is predominately expressed in the human ventricle, while MHC-α is predominantly expressed in human atria.[citation needed]

Function[edit]

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,[8] then the S1-S2 myosin lever arm rotates ~70° about the converter domain and drives actin filaments towards the M-line.[9]

Clinical significance[edit]

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.[10] 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.[11]

A myopathy caused by a MYH7 mutation in pigs.

References[edit]

  1. ^ Quiat D, Voelker KA, Pei J, Grishin NV, Grange RW, Bassel-Duby R, Olson EN (Jun 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). doi:10.1073/pnas.1107413108. PMID 21633012. 
  2. ^ http://www.heartproteome.org/copa/ProteinInfo.aspx?QType=Protein%20ID&QValue=P12883.  Missing or empty |title= (help)
  3. ^ Zong, N. C.; Li, H; Li, H; Lam, M. P.; Jimenez, R. C.; Kim, C. S.; Deng, N; Kim, A. K.; Choi, J. H.; Zelaya, I; Liem, D; Meyer, D; Odeberg, J; Fang, C; Lu, H. J.; Xu, T; Weiss, J; Duan, H; Uhlen, M; Yates Jr, 3rd; Apweiler, R; Ge, J; Hermjakob, H; Ping, P (2013). "Integration of cardiac proteome biology and medicine by a specialized knowledgebase". Circulation Research 113 (9): 1043–53. doi:10.1161/CIRCRESAHA.113.301151. PMC 4076475. PMID 23965338.  edit
  4. ^ Palmer BM (Sep 2005). "Thick filament proteins and performance in human heart failure". Heart Failure Reviews 10 (3). doi:10.1007/s10741-005-5249-1. PMID 16416042. 
  5. ^ Harris SP, Lyons RG, Bezold KL (Mar 2011). "In the thick of it: HCM-causing mutations in myosin binding proteins of the thick filament". Circulation Research 108 (6). doi:10.1161/CIRCRESAHA.110.231670. PMID 21415409. 
  6. ^ Palmer BM (Sep 2005). "Thick filament proteins and performance in human heart failure". Heart Failure Reviews 10 (3). doi:10.1007/s10741-005-5249-1. PMID 16416042. 
  7. ^ Alpert NR, Brosseau C, Federico A, Krenz M, Robbins J, Warshaw DM (Oct 2002). "Molecular mechanics of mouse cardiac myosin isoforms". American Journal of Physiology. Heart and Circulatory Physiology 283 (4). doi:10.1152/ajpheart.00274.2002. PMID 12234796. 
  8. ^ McKillop DF, Geeves MA (Aug 1993). "Regulation of the interaction between actin and myosin subfragment 1: evidence for three states of the thin filament". Biophysical Journal 65 (2). doi:10.1016/S0006-3495(93)81110-X. PMID 8218897. 
  9. ^ Tyska MJ, Warshaw DM (Jan 2002). "The myosin power stroke". Cell Motility and the Cytoskeleton 51 (1). doi:10.1002/cm.10014. PMID 11810692. 
  10. ^ Geisterfer-Lowrance, A. A.; Kass, S; Tanigawa, G; Vosberg, H. P.; McKenna, W; Seidman, C. E.; Seidman, J. G. (1990). "A molecular basis for familial hypertrophic cardiomyopathy: A beta cardiac myosin heavy chain gene missense mutation". Cell 62 (5): 999–1006. PMID 1975517.  edit
  11. ^ Park JM, Kim YJ, Yoo JH, Hong YB, Park JH, Koo H, Chung KW, Choi BO (Jul 2013). "A novel MYH7 mutation with prominent paraspinal and proximal muscle involvement". Neuromuscular Disorders 23 (7). doi:10.1016/j.nmd.2013.04.003. PMID 23707328. 

Further reading[edit]

  • Jaaskelainen P, Miettinen R, Karkkainen P, Toivonen L, Laakso M, Kuusisto J (2004). "Genetics of hypertrophic cardiomyopathy in eastern Finland: few founder mutations with benign or intermediary phenotypes". Annals of Medicine 36 (1): 23–32. doi:10.1080/07853890310017161. PMID 15000344. 
  • Kamisago M, Schmitt JP, McNamara D, Seidman C, Seidman JG (2007). "Sarcomere protein gene mutations and inherited heart disease: a beta-cardiac myosin heavy chain mutation causing endocardial fibroelastosis and heart failure". Novartis Foundation Symposium 274: 176–89; discussion 189–95, 272–6. doi:10.1002/0470029331.ch11. PMID 17019812. 

External links[edit]

  1. ^ Zong, N. C.; Li, H; Li, H; Lam, M. P.; Jimenez, R. C.; Kim, C. S.; Deng, N; Kim, A. K.; Choi, J. H.; Zelaya, I; Liem, D; Meyer, D; Odeberg, J; Fang, C; Lu, H. J.; Xu, T; Weiss, J; Duan, H; Uhlen, M; Yates Jr, 3rd; Apweiler, R; Ge, J; Hermjakob, H; Ping, P (2013). "Integration of cardiac proteome biology and medicine by a specialized knowledgebase". Circulation Research 113 (9): 1043–53. doi:10.1161/CIRCRESAHA.113.301151. PMC 4076475. PMID 23965338.  edit