Tropomyosin, in association with the troponin complex, plays a central role in the calcium dependent regulation of muscle contraction. Homodimer. Ubiquitous, but especially prevalent in the anterior muscle bundles associated with legs. Expression in the mid and posterior regions is probably related to the numerous, small muscle bundles associated with the digestive and reproductive systems (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 sheep (PubMed:16817997, PubMed:15679630). Binds to IgE of sheep allergic to scab mites (PubMed:15679630). Belongs to the tropomyosin family.