Figure 2

PEITC inhibits wild type MEKK1, but not the C1238V mutant in cells and in vitro. A. CV-1 cells expressing the catalytic domain fragment of wild type MEKK1 (top panel) or the C1238V mutant (bottom panel) were treated with PEITC at the indicated concentrations for 1 hour at 37°C. Kinases were purified on chitin beads and assayed for activity by in vitro kinase assay. B. Purified wild type MEKK1 (top panel) or the C1238V mutant (bottom panel) were treated with PEITC at the indicated concentrations for 30 minutes at room temperature. PEITC inhibited wild type MEKK1, but not the C1238V mutant both after treatment of intact cells and treatment of purified protein in vitro, indicating that the inhibition of MEKK1 is a direct effect on the kinase itself and requires the cysteine at position 1238.