(A) and (B), Single turnover GTP binding assay. Time-course of [35S]GTPγS binding to 100 nM purified 6xHIS-Gpa1 in the presence of 200 nM GST-Arr4. Results are the mean ± SEM of duplicate samples, and are presented as percent of maximum bound (saturated binding occurred between 50-75%).
(A) with 500 nM CuSO4 added.
(B) Same as in A, but no copper added to the reaction.
(C) Steady state GTP hydrolysis assay. Time-course of Pi released in the presence or absence of 6xHIS-Gpa1 (250 nM), GST-Arr4 (500 nM), and copper (500 nM). Results are the mean ± SEM of duplicate samples.