Cardiac titin isoforms are coexpressed in the half-sarcomere and extend independently

K. Trombitás, Y. Wu, D. Labeit, S. Labeit, H. Granzier

Research output: Contribution to journalArticlepeer-review

69 Scopus citations


Titin, the third myofilament type of cardiac muscle, contains a molecular spring segment that gives rise to passive forces in stretched myocardium and to restoring forces in shortened myocardium. We studied cardiac titin isoforms (N2B and N2BA) that contain length variants of the molecular spring segment. We investigated how coexpression of isoforms takes place at the level of the half-sarcomere, and whether coexpression affects the extensibility of the isoforms. Immunoelectron microscopy was used to study local coexpression of isoforms in a range of species. It was found that the cardiac sarcomere of large mammals coexpresses N2B and N2BA titin isoforms at the level of the half-sarcomere, and that when coexpressed, the isoforms act independently of one another. Coexpressing isoforms at varying ratios results in modulation of the passive mechanical behavior of the sarcomere without impacting other functions of titin and allows for adjustment of the diastolic properties of the myocardium.

Original languageEnglish (US)
Pages (from-to)H1793-H1799
JournalAmerican Journal of Physiology - Heart and Circulatory Physiology
Issue number4 50-4
StatePublished - 2001


  • Diastole
  • Elasticity
  • Mechanics
  • Physiology
  • Structure

ASJC Scopus subject areas

  • Physiology
  • Cardiology and Cardiovascular Medicine
  • Physiology (medical)


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