Tropomyosin, in association with the troponin complex, plays a central role in the calcium dependent regulation of muscle contraction. Homodimer. Expressed in striated skeletal muscle (at protein level). The molecule is in a coiled coil structure that is formed by 2 polypeptide chains. The sequence exhibits a prominent seven-residues periodicity. Causes an allergic reaction in human. Binds to IgE in 50% of 53 cockroach-allergic patients living in Brazil. Belongs to the tropomyosin family.