FIG. 4.

Phosphorylation of synthetic peptide substrates by Pho85p-Pcl10p. (A) Kinetics of peptide phosphorylation. The indicated concentrations of synthetic peptides Gsy2-654 (○), Gsy2-667 (□), and Pho4-114 (●) were incubated with 50 nM Pho85p and 2 μM Pcl10p, and the initial rate of peptide phosphorylation was determined. Data were analyzed as described in Materials and Methods. (B) Phosphorylation of synthetic peptides by Pho85p shows a dependence upon Pcl10p. Synthetic peptide Gsy2-654 (2.5 mM) was incubated with 50 nM Pho85p and the indicated concentrations of Pcl10p. The data were analyzed as described in Materials and Methods. The concentration of Pcl10p required to give half-maximal peptide phosphorylation was calculated to be ∼0.2 μM.