Tropomyosin, in association with the troponin complex, plays a central role in the calcium dependent regulation of muscle contraction. Homodimer. Expressed in muscle (at protein level) (PubMed:23840718, PubMed:23018510). Expressed in pincer muscles (PubMed:23840718). 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. Natural and recombinant protein binds to IgE of patients allergic to crabs (PubMed:23840718, PubMed:23393908, PubMed:23018510). Recombinant protein binds to IgE in 75% of the 12 shellfish-allergic patients tested. Heating increases IgE-binding activity. Cross-reacts with giant tiger prawn tropomyosin allergen Pen m 1.0101 (PubMed:23840718). Cross-reacts with crucifix crab tropomyosin allergen Cha f 1 (PubMed:23393908). Belongs to the tropomyosin family.