Polymorphism in tropomyosin structure and function

  • Miro Janco
  • Worawit Suphamungmee
  • Xiaochuan Li
  • William Lehman
  • Sherwin S. Lehrer
  • Michael A. Geeves


Tropomyosins (Tm) in humans are expressed from four distinct genes and by alternate splicing >40 different Tm polypeptide chains can be made. The functional Tm unit is a dimer of two parallel polypeptide chains and these can be assembled from identical (homodimer) or different (heterodimer) polypeptide chains provided both chains are of the same length. Since most cells express multiple isoforms of Tm, the number of different homo and heterodimers that can be assembled becomes very large. We review the mechanism of dimer assembly and how preferential assembly of some heterodimers is driven by thermodynamic stability. We examine how in vitro studies can reveal functional differences between Tm homo and heterodimers (stability, actin affinity, flexibility) and the implication for how there could be selection of Tm isomers in the assembly on to an actin filament. The role of Tm heterodimers becomes more complex when mutations in Tm are considered, such as those associated with cardiomyopathies, since mutations can appear in only one of the chains.


Heterodimers and homodimers Tropomyosin isoforms Coiled-coils Actin Cardiomyopathy mutations 







Hypertrophic cardiomyopathy


Dilated cardiomyopathy


Heterodimer of αTm where one chain carries the mutation


High molecular weight


Low molecular weight


Chicken gizzard αTm


Rabbit skeletal αTm


Apparent persistence length


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Copyright information

© Springer Science+Business Media Dordrecht 2013

Authors and Affiliations

  • Miro Janco
    • 1
  • Worawit Suphamungmee
    • 2
  • Xiaochuan Li
    • 2
  • William Lehman
    • 2
  • Sherwin S. Lehrer
    • 3
  • Michael A. Geeves
    • 1
  1. 1.School of BiosciencesUniversity of KentCanterburyUK
  2. 2.Department of Physiology and BiophysicsBoston University School of MedicineBostonUSA
  3. 3.Boston Biomedical Research InstituteWatertownUSA

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