FIGURE 9.

Arginine 336 of Aup1, within the RXKL motif, is required for phosphatase activity. A, the purified C-terminal PP2C motif iteration (amino acids 213–419) shows PP2C-type phosphatase activity. 2 μg of purified Aup1 (amino acids 213–419) or purified GFP control were assayed for phosphatase activity in the presence of Mg²⁺ or Mn²⁺, as detailed under “Experimental Procedures.” B, steady state kinetic analysis of purified Aup1 (amino acids 213–419) versus the D306A and R336A variants. Results are representative of three independent determinations.