Is the expression of TPM1kappa, a novel sarcomeric tropomyosin isoform, developmentally regulated in vertebrate hearts?
Dipak. K.Dube (1,2), Elisabeth Ehle (3), Christopher R. Denz (1,2), Arun Rajan (1), Syamalima Dube (1), and Robert W. Zajdel (2) Departments of (1) Medicine and (2) Cell & Developmental Biology, SUNY Upstate Medical University, Syracuse, New York 13210; (3) The Randall Center, Guy’s Campus, King’s College London, UK Tropomyosin (TM) is one of six proteins comprising the thin filaments of sarcomeres. In vertebrates, there are four tropomyosin genes (TPM1, TPM2, TPM3, and TPM4), each being capable of generating more than one isoforms via alternative splicing. Previous studies of the TPM1 gene using Northern blot and ribonuclease protection assays identified the expression of nine isoforms generated by the alternate splicing of exons. Of the nine, one isoform, TPM1alpha, with exons 1a, 2b, 3, 4, 5, 6b, 7, 8, and 9a/b is known to be specifically expressed in human striated muscles. However, we have identified and characterized an alternatively spliced isoform of the TPM1 gene, which is exp
