The S211F and H418R mutations alter GlyRS dimerization and the release kinetics of the cognate tRNA^Gly. (A), Size-exclusion chromatography of purified recombinant hGlyRS proteins. D:M, dimer-to-monomer ratio. (B), K_on and K_off values of tRNA^Gly-GCC binding and release, respectively, to the dimer form of the indicated hGlyRS variants. The percentage in parentheses denotes the frequency of a measured value.