Comparison of the specific activities and response to lipid of Ppt1p and PP5. (A) Recombinant Ppt1p (lane 1) and Ppt1p (1–504) (lane 2) were expressed in Escherichia coli, purified by GST-agarose chromatography and cleaved with thrombin. Samples containing approximately 7.5 μg of protein were resolved by SDS-PAGE on a 10% polyacrylamide gel and visualized by Coomassie staining. The migration of molecular weight standards is indicated to the left. (B) Phosphatase activity of Ppt1p or PP5 was assayed for 10 min at 30°C in the absence (□) or presence (■) of 250 μM AA using 10 μM 32P-MBP or 32P-casein as substrate. Data are the average ± S.D. from assays performed in triplicate. Three independent experiments performed under similar conditions yielded similar results.