Which domain of myosin contains ATPase activity?
Myosin architecture dissected by limited proteolysis yields fragments S1 head, heavy meromyosin HMM containing two heads plus coiled tail portion, and light meromyosin LMM tail. Crystallographic structures of Dictyostelium and chicken myosin II S1 show N terminal globular domain 80 kilodalton comprising upper 50k lower 50k subdomains forming actin interface, central 25k P loop subdomain containing nucleotide binding site with Walker A motif GXXXXGKT, Switch I 200 to 205, Switch II 454 to 459 coordinating MgATP, converter domain linking to lever arm. ATPase activity measured by phosphate releas
Ref: Pollard and Earnshaw, Cell Biology, Chapter 12: Myosin Head Domain ATPase Activity.