The multiple roles of titin in muscle contraction and force production
Titin is a filamentous protein spanning the half-sarcomere, with spring-like properties in the I-band region. Various structural, signaling, and mechanical functions have been associated with titin, but not all of these are fully elucidated and accepted in the scientific community. Here, I discuss the primary mechanical functions of titin, including its accepted role in passive force production, stabilization of half-sarcomeres and sarcomeres, and its controversial contribution to residual force enhancement, passive force enhancement, energetics, and work production in shortening muscle. Finally, I provide evidence that titin is a molecular spring whose stiffness changes with muscle activation and actin-myosin-based force production, suggesting a novel model of force production that, aside from actin and myosin, includes titin as a "third contractile" filament. Using this three-filament model of sarcomeres, the stability of (half-) sarcomeres, passive force enhancement, residual force enhancement, and the decrease in metabolic energy during and following eccentric contractions can be explained readily.
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Aiheet: | harjoittelu voima, vahvuus lihas biokemia supistus |
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Aihealueet: | biologiset ja lääketieteelliset tieteet |
Julkaisussa: | Biophysical Reviews |
Julkaistu: |
2018
|
Vuosikerta: | 10 |
Numero: | 4 |
Sivuja: | 1187-1199 |
Julkaisutyypit: | elektroninen julkaisu |
Kieli: | englanti (kieli) |
Taso: | keskitaso |