biostudies-literatureAgafonov RVNIAMS NIH HHS13397-402https://www.ebi.ac.uk/biostudies/studies/S-EPMC2533201biostudies-literatureUnknown105(36)We have engineered a mutant of Dictyostelium discoideum (Dicty) myosin II that contains the same fast-reacting "SH1" thiol as in muscle myosin, spin-labeled it, and performed electron paramagnetic resonance (EPR) to compare the structure of the force-generating region of the two myosins. Dicty myosin serves as a model system for muscle myosin because of greater ease of mutagenesis, expression, and crystallization. The catalytic domains of these myosins have nearly identical crystal structures in the apo state, but there are significant differences in ATPase kinetics, and there are no crystal structures of skeletal muscle myosin with bound nucleotides, so another structural technique is needed. Previous EPR studies, with a spin label attached to SH1 in muscle myosin, have resolved the key sProceedings of the National Academy of Sciences of the United States of AmericaMuscle and nonmuscle myosins probed by a spin label at equivalent sites in the force-generating domain.PMC2533201R37 AR032961AR53562K25 AR053562R01 AR032961AR32961Thomas DDNesmelov YEAgafonov RVTitus MAfalseMuscle and nonmuscle myosins probed by a spin label at equivalent sites in the force-generating domain.We have engineered a mutant of Dictyostelium discoideum (Dicty) myosin II that contains the same fast-reacting "SH1" thiol as in muscle myosin, spin-labeled it, and performed electron paramagnetic resonance (EPR) to compare the structure of the force-generating region of the two myosins. Dicty myosin serves as a model system for muscle myosin because of greater ease of mutagenesis, expression, and crystallization. The catalytic domains of these myosins have nearly identical crystal structures in the apo state, but there are significant differences in ATPase kinetics, and there are no crystal structures of skeletal muscle myosin with bound nucleotides, so another structural technique is needed. Previous EPR studies, with a spin label attached to SH1 in muscle myosin, have resolved the key s2008-01-01T00:00:00Z2008 Sep2026-05-03T20:57:07.558Z2019-03-27T00:16:33ZS-EPMC25332011876579910.1073/pnas.0801342105