Striated muscle tropomyosin is classically described as consisting of 10 exons, 1a, 2b, 3, 4, 5, 6b, 7, 8, and 9a/b, in both skeletal and cardiac muscle. Experiments in our laboratory have demonstrated expression of a naturally occurring chimeric isoform of tropomyosin that has both smooth and striated muscle exons. The chimeric isoform has a replacement of exon 2a for 2b that is commonly found in striated isoforms. GFP constructs were used to demonstrate translation and incorporation into organized myofibrils. Antisense oligonucleotide transfection decreased the expression of this isoform and disrupted organization and function.
Wang J., H. Thurston, E. Essandoh, M. Otto, M. Han, A. Rajan, S. Dube, R. W. Zajdel, J. M. Sanger, K.K. Linask, D.K. Dube, J.W. Sanger. (2008) Tropomyosin expression and dynamics in developing avian embryonic muscles. Cell Motil. Cytoskel. 65:379-392.
Zajdel, R. W., H. Thurston, S. Prayaga, S. Dube, B.J. Poiesz, D. K. Dube. (2007). A reduction of tropomyosin limits development of sarcomeric structures in cardiac mutant hearts of the Mexican axolotl. Cardiovasc Toxicol. 7:235-246.
Zajdel, R. W., M. D. McLean, Denz, C.R., Dube S., Thurston H. L., Poiesz, B. J., D. K. Dube. (2006). Differential expression of tropomyosin during segmental heart development in Mexican axolotl. J. Cell Biochem. 99: 952-965.
Zajdel, R. W., C. R. Denz, A. Narshi, Syamalima Dube, D. K. Dube. (2005). Anti-sense mediated inhibition of expression of the novel striated tropomyosin isoform TPM1κ disrupts myofibril organization in embryonic axolotl hearts. J. Cell. Biochem. 95: 840-848.
Denz, C. R., A. Narshi, R. W. Zajdel, D. K. Dube. (2004). Expression of a novel cardiac-specific tropomyosin isoform in humans.Biochem. Biophys. Res. Commun. 320: 1291-129.