Effects of cpFtsY mutations on its stimulated GTPase reaction with cpSRP54. (A, B) The stimulated GTPase reactions of wildtype cpFtsY (○), and mutants cpFtsY(A169W) (part A, ● and inset) and cpFtsY(A168W) (part B, ● and inset). (C) Inhibition assays for determining the affinities of mutants cpFtsY(A168W) (○) and cpFtsY(A169W) (●) for cpSRP54. The figures show representative data, and Table 1 summarizes the average values from two or more measurements. (D) Gel filtration analyses of stable complex formation of cpSRP54 with wildtype cpFtsY (black) and mutants cpFtsY D163A (blue), R166A (green), A168W (red), A169L (magenta) and A169W (cyan).