Tropomyosin alpha-3 chain （TPM3） belongs to the tropomyosin family of actin-binding proteins involved in the contractile system of striated and smooth muscles and the cytoskeleton of non-muscle cells. Tropomyosins are dimers of coiled-coil proteins which polymerize end-to-end along the major groove in most actin filaments. Tropomyosins give stability to the filaments and regulate access of other actin-binding proteins. In muscle cells， tropomyosins regulate muscle contraction by controlling the binding of myosin heads to the actin filament. Mutations in the TPM3 gene cause autosomal dominant nemaline myopathy， and oncogenes formed by chromosomal translocations involving this locus are linked with cancer.
