that tropomyosins have the highest number of such motifs, and thus a very high propensity to act as autoantigens. In addition to the role tropomyosins play in ulcerative colitis, tropomyosin antibodies have also been reported in acute rheumatic fever and the inflammatory disorder Behcet's syndrome. In both instances, it is unclear as to whether these antibodies play a direct role in the pathogenesis of these human conditions or reflect the high antigenicity of tropomyosins released from compromised cells. Muscle diseases Nemaline myopathy is a muscle disease that is characterised by the presence of electron-dense rod bodies in skeletal muscle fibers. These electron-dense rod bodies are composed mainly of α-actinin and actin. The disorder is often clinically categorized into several groups, including mild (typical), intermediate, severe, and adult-onset; however, these distinctions are somewhat ambiguous, as the categories frequently overlap. Causative mutations have been detected in skeletal α-actinin, tropomyosin, nebulin, and troponin. Within humans, mutations in both the γ-Tropomyosin and β-Tropomyosin genes have been identified. No mutations in the α-Tropomyosin gene have been identified in this condition for humans. Allergies Tropomyosin is the primary protein responsible for shellfish allergies, including crustaceans and molluscs. Tropomyosin also causes some cases of cockroach allergy. Tools and technologies to study tropomyosins Antibodies Given the vast array of processes that this protein has been reported to be involved with, there is great interest in tropomyosin isoforms within the scientific community. One way in which specific isoforms of this protein can be studied in detail is through the use of antibodies. These specific antibodies can be used in protein-blotting experiments and applied to cells or tissue sections and observed under a microscope. This allows researchers not only to determine the level or concentration of an isoform or a group of isoforms, but to also identify the cellular location of a particular isoform and associations with other cellular structures or proteins. At the present time, there are many commercially available antibodies; however, many of these antibodies are sold with minimal information regarding the antigen used to raise the antibody and therefore, the isoform specificity; as such, some research groups develop their own antibodies. Before these antibodies can be used, they must be extensively characterised, a process whereby the specificity of the antibody is examined to ensure that the antibody does not cross-react with other tropomyosins or other proteins. References External links Diagrams and explanations at biomol.uci.edu Muscular system