Tropomyosin, in association with the troponin complex, plays a central role in the calcium dependent regulation of muscle contraction. Homodimer. 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 7% of the 133 patients allergic to arthropods including shrimp, house fly, household insects, mosquito, cockroach, spider and mites. Induces histamine release from basophils that are passively sensitized with IgE from silverfish tropomyosin-allergic patient. Belongs to the tropomyosin family.