FIG. 7.

Binding of ³H-PD 184352 to MEK variants. A scintillation proximity assay was used to assess binding of ³H-PD 184352 to different MEK mutants. (A) A 1 μM concentration of ³H-PD 184352 was incubated with 200 or 500 nM wild-type MEK or L115P MEK, and the amount of bound ³H was determined as described elsewhere. (B) A 500 nM concentration of MEK proteins was incubated with 300 nM ³H-PD 184352, and the amount of associated ³H was determined. Nonspecific values were determined in the absence of MEK protein and subtracted from the values shown. Values are averages of four replicate samples are presented. Error bars reflect the standard error of the mean.