Tropomyosin: Difference between revisions

'''Tropomyosin (TPM)''' has a 4-helix coiled structure.  It regulates the binding of myosin thus regulating muscle contraction <ref>PMID:9108196</ref>. In its locked conformation it binds troponin T (TnnT) and prevents the binding of myosin to actin. When Ca++ ions bind to TnnT, the TPM assumes an open conformation and myosin can bind to actin. The images at the top and at the right correspond to one representative TPM structure, ''i.e.'' Tropomyosin from pig ([[1c1g]]). You can  <scene name='Tropomyosin/Cv/2'>enlarge the image</scene> at the right for clarity. The dimers of TPM in the asymmetric unit ([[1c1g]]) are <scene name='Tropomyosin/Cv/6'>antiparallel</scene>, with their C-terminal ends overlapping by about 2/3 of the molecular length. This suggests head-to-tail packing of TPM, which is very important for its interaction with actin <ref>PMID:10651038</ref>.