Characterization of a cDNA defining a gene family encoding TM30p1, a human fibroblast tropomyosin.

We have isolated a cDNA that contains the complete coding sequence of a 3.0 X 10(3) base human fibroblast mRNA together with a large part of its 3' untranslated sequence. The deduced protein sequence is very similar if not identical to the sequence of horse platelet tropomyosin, a 247 amino acid protein. In vitro translation of an SP6 transcript of this cDNA reveals that the protein product of the 3.0 X 10(3) base mRNA is TM30p1, one of the five proteins in human fibroblasts that have been shown to possess the physical and chemical characteristics of tropomyosin. This mRNA is encoded by a gene family that consists of a functional gene and multiple RNA-copy pseudogenes. This family of sequences is distinct from the gene family encoding TM30nm, a cytoskeletal tropomyosin very similar in electrophoretic mobility to TM30p1, but which shows significant differences in primary structure.