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Cooperative activation of the cardiac myofilament: the pivotal role of tropomyosin.
| Content Provider | Semantic Scholar |
|---|---|
| Author | Vanburen, Peter C. Palmer, Bradley M. |
| Copyright Year | 2010 |
| Abstract | The contraction and relaxation of the beating heart are mediated by highly coordinated processes that allow rapid activation and deactivation of the myofilaments. The sarcomere is the fundamental contractile element, and its shortening is the result of the myosin-containing thick filament sliding past the actin-containing thin filament. Fueled by ATP hydrolysis, myosin is the molecular motor that drives sarcomere shortening through a cyclic, ratchet-like interaction with actin. A critical component of cardiac contraction is the regulation of myosin-actin interactions, which are governed predominantly by the thin-filament regulatory proteins troponin and tropomyosin. Article see p 410 A change in myofilament isoform composition is one mechanism by which myocardial contractile performance may be affected in heart failure. The fast isoform of myosin heavy chain, α-MHC, normally accounts for approximately 10% of the fractional content in healthy human myocardium compared with 90% β-MHC, but it is reduced to nearly undetectable concentrations during heart failure.1 In animal models, a change in myofilament performance can be detected with MHC isoform shifting, and the slight loss of α-MHC in human heart failure has been touted by some,2 although not by all,3 as an underlying factor in the reduced cardiac function. Enhanced incorporation of the atrial isoform of the myosin essential light chain in the failing human ventricle has been observed and correlates with an increase in myofilament calcium sensitivity.4 Finally, a shift in troponin T isoform composition is reported in human heart failure,5 with likely modest effects on contractility.6 In this issue of Circulation , Rajan et al7 identify a shift in tropomyosin isoform expression in human heart failure and investigate its possible functional consequences. As discussed, this study represents an important contribution to our understanding of how myofilament protein isoforms, through the cooperative activation of the thin filament, … |
| Starting Page | 109 |
| Ending Page | 116 |
| Page Count | 8 |
| File Format | PDF HTM / HTML |
| Alternate Webpage(s) | http://circ.ahajournals.org/content/circulationaha/121/3/351.full.pdf?download=true |
| PubMed reference number | 20100986v1 |
| Alternate Webpage(s) | https://doi.org/10.1161/CIR.0b013e3181d0b947 |
| DOI | 10.1161/cir.0b013e3181d0b947 |
| Journal | Circulation |
| Volume Number | 121 |
| Issue Number | 3 |
| Language | English |
| Access Restriction | Open |
| Subject Keyword | Actin myofilament Cytoskeletal Filaments Intrinsic drive Microfilaments Myocardial Contraction Myofilaments Myosin myofilament Sarcomeres Tropomyosin |
| Content Type | Text |
| Resource Type | Article |
