title: The molecular basis of muscle contraction.
abstract: Muscle contraction takes place by the cyclic interaction of two-stranded helical actin filaments with protuberances from the myosin filaments known as cross-bridges. The nature of the contractile process demands that the myosin cross-bridge be highly polymorphic. Biochemical evidence points to the cross-bridge having a domain structure such that contraction may be a manifestation of the rearrangement of these subunits. An essential step in contraction may be the initial binding of a small hinged domain of the cross-bridge (the 'nose-cone') to actin, followed by a series of changes ending in the formation of a second union (the rigor bond) with an actin monomer in the neighbouring strand of the actin helix.
mesh_terms: D000199:Actins / Q000378:metabolism*; D000205:Actomyosin / Q000378:metabolism; D000255:Adenosine Triphosphate / Q000378:metabolism; D000818:Animals; D046911:Macromolecular Substances; D008958:Models, Molecular; D009119:Muscle Contraction; D009132:Muscles / Q000378:metabolism*; D009218:Myosins / Q000378:metabolism*; D011487:Protein Conformation
chemical_list: D000199:Actins; D046911:Macromolecular Substances; D000255:Adenosine Triphosphate; D000205:Actomyosin; D009218:Myosins