A cDNA encoding a muscle-type tropomyosin cloned from a human epithelial cell line: identity with human fibroblast tropomyosin TM1.

Tropomyosins (TM) expressed by human epithelial cells have only recently been characterized, and no sequence data for them has appeared. We cloned a cDNA encoding a high molecular weight, muscle-type TM from a LS174T human colon carcinoma epithelial cell cDNA library. On sequence analysis this cDNA (TMe1) was virtually identical to the previously reported sequence for human fibroblast TM1 encoded by the hTM beta gene. Expression of TM1/TMe1 mRNA and protein are low in epithelial cells compared with fibroblasts. The results indicate that cells of different developmental lineages (entodermal and mesodermal) can produce identical TM beta gene splice products while regulating expression of those transcripts in a lineage-specific way.