This gene encodes beta-tropomyosin; a member of the actin filament binding protein family; and mainly expressed in slow; type 1 muscle fibers. Mutations in this gene can alter the expression of other sarcomeric tropomyosin proteins; and cause cap disease; nemaline myopathy and distal arthrogryposis syndromes. Alternatively spliced transcript variants encoding different isoforms have been found for this gene.