Journal of Molecular Evolution

, Volume 27, Issue 3, pp 228–235

Evolution of tropomyosin functional domains: Differential splicing and genomic constraints


  • S. Colote
    • INSERM U-249, CRBM du CNRSUniversité de Montpellier I
  • J. Sri Widada
    • INSERM U-249, CRBM du CNRSUniversité de Montpellier I
  • C. Ferraz
    • INSERM U-249, CRBM du CNRSUniversité de Montpellier I
  • F. Bonhomme
    • Institut des Sciences de l'Évolution, CNRS UA 327USTL pl. E. Bataillon
  • J. Marti
    • INSERM U-65Institut de Biologie Bd Henri IV
  • J. -P. Liautard
    • INSERM U-249, CRBM du CNRSUniversité de Montpellier I

DOI: 10.1007/BF02100079

Cite this article as:
Colote, S., Widada, J.S., Ferraz, C. et al. J Mol Evol (1988) 27: 228. doi:10.1007/BF02100079


We have cloned and determined the nucleotide sequence of a complementary DNA (cDNA) encoded by a newly isolated human tropomyosin gene and expressed in liver. Using the leastsquare method of Fitch and Margoliash, we investigated the nucleotide divergences of this sequence and those published in the literature, which allowed us to clarify the classification and evolution of the tropomyosin genes expressed in vertebrates. Tropomyosin undergoes alternative splicing on three of its nine exons. Analysis of the exons not involved in differential splicing showed that the four human tropomyosin genes resulted from a duplication that probably occurred early, at the time of the amphibian radiation. The study of the sequences obtained from rat and chicken allowed a classification of these genes as one of the types identified for humans.

The divergence of exons 6 and 9 indicates that functional pressure was exerted on these sequences, probably by an interaction with proteins in skeletal muscle and perhaps also in smooth muscle; such a constraint was not detected in the sequences obtained from nonmuscle cells. These results have led us to postulate the existence of a protein in smooth muscle that may be the counterpart of skeletal muscle troponin.

We show that different kinds of functional pressure were exerted on a single gene, resulting in different evolutionary rates and different convergences in some regions of the same molecule.

Codon usage analysis indicates that there is no strict relationship between tissue types (and hence the tRNA precursor pool) and codon usage. G+C content is characteristic of a gene and does not change significantly during evolution. These results are in good agreement with an isochore composition of the genome, and thus suggest a similar chromosomal environment in chicken, rat, and human.

Key words

TropomyosinDifferential splicingEvolutionIsochoreCodon usageSequence convergenceFunctional constraints

Copyright information

© Springer-Verlag New York Inc 1988