Extraction and Replacement of the Tropomyosin–Troponin Complex in Isolated Myofibrils

  • Beatrice Scellini
  • Nicoletta Piroddi
  • Corrado Poggesi
  • Chiara Tesi
Part of the Advances in Experimental Medicine and Biology book series (AEMB, volume 682)


Tropomyosin (Tm) is an essential component in the regulation of striated muscle contraction. Questions about Tm functional role have been difficult to study because sarcomere Tm content is not as easily manipulated as Troponin (Tn). Here we describe the method we recently developed to replace Tm-Tn of skeletal and cardiac myofibrils from animals and humans to generate an experimental model of homogeneous Tm composition and giving the possibility to measure a wide range of mechanical parameters of contraction (e.g. maximal force and kinetics of force generation). The success of the exchange was determined by SDS–PAGE and by mechanical measurements of calcium dependent force activation on the reconstituted myofibrils. In skeletal and cardiac myofibrils, the percentage of Tm replacement was higher than 90%. Maximal isometric tension was 30–35% lower in the reconstituted myofibrils than in control myofibrils but the rate of force activation (kACT) and that of force redevelopment (kTR) were not significantly changed. Preliminary results show the effectiveness of Tm replacement in human cardiac myofibrils. This approach can be used to test the functional impact of Tm mutations responsible for human cardiomyopathies.


Regulatory proteins Tropomyosin Troponin Myofibrils Cardiac Skeletal 



This work was supported by 7th Framework Programs of the European Union (STREP Project “BIG-HEART”, grant agreement 241577) and by Telethon-Italy (GGP07133). Authors gratefully acknowledge Dr. Earl Homsher for helpful discussion and technical advice.


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Copyright information

© Springer Science+Business Media, LLC 2010

Authors and Affiliations

  • Beatrice Scellini
  • Nicoletta Piroddi
  • Corrado Poggesi
  • Chiara Tesi
    • 1
  1. 1.Dipartimento di Scienze FisiologicheUniversità di FirenzeFirenzeItaly

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