AtPP2CF1 had functional PP2C activity. (A) Complementation test of the yeast ptc1 mutation by AtPP2CF1. The yeast ptc1 knockout strain was transformed with constructs 1 (pYC2/CT, empty vector), 2 (pYC2/CT PTC1), 3 (pYC2/CT AtPP2CF1), or 4 (pYC2/CT ABI1) under the control of the galactose-inducible GAL1 promoter. Serial dilutions of exponentially growing yeast cell cultures were spotted on an SG plate lacking uracil, and growth was observed after 4 d at the permissive temperature (30°C, left) or the restrictive temperature (37°C, right). (B, C) Phosphatase activities of GST-AtPP2CF1 (B) and GST-ABI1 (C). Phosphatase assays were performed as described in the Materials and methods. Purified GST-AtPP2CF1 or GST-ABI1 was incubated with no substrate (No), 100 μM substrate (Su), 100 μM substrate plus 50mM NaF (Fl), 1mM NaVO3 (Va), 10 μM okadaic acid (Ok), or 10mM EDTA (Ed). Values represent the mean ± SD of three independent experiments.