title: Location of the ATPase site of myosin determined by three-dimensional electron microscopy.
abstract: Both ATP hydrolysis by myosin and the accompanying cyclic association-dissociation of actin and myosin are essential for muscle contraction. It is important for understanding the molecular mechanism of contraction to know the three-dimensional locations of the two major functional sites of myosin: the ATPase site and the actin-binding site. We have determined the position of the ATPase site of myosin using three-dimensional image reconstruction from electron micrographs and site-specific labelling with the avidin-biotin system. The ATPase site is about 5 nm from the tip of the myosin head and is about 4 nm away from the actin-binding site of myosin. This is the first report of the three-dimensional location of an enzyme active site by electron microscopy.
mesh_terms: D000199:Actins / Q000378:metabolism; D000244:Adenosine Diphosphate / Q000378:metabolism; D000251:Adenosine Triphosphatases; D001360:Avidin / Q000378:metabolism; D001665:Binding Sites; D055598:Chemical Phenomena; D002627:Chemistry, Physical; D008854:Microscopy, Electron; D008958:Models, Molecular; D008961:Models, Structural; D014961:X-Ray Diffraction
chemical_list: D000199:Actins; D001360:Avidin; D000244:Adenosine Diphosphate; D000251:Adenosine Triphosphatases