Figure 2.

Phosphorylation of GST-1.1. (A) GST-1.1 expressed in Escherichia coli was purified and incubated with 1, 2, or 3 μl of JNK3 in the presence of γ-³³P-ATP at 30°C for 20 min. Reactions were stopped by the addition of SDS sample buffer and resolved on the gel (lanes 2, 3, and 4). The asterisk (∗) indicates the phosphorylated GST-1.1. GST–c-Jun (1 μg) is shown in lane 1 as a positive control. (B) Comparison of phosphorylation of GST-1.1, myelin basic protein, and GST–c-Jun by three different kinases: C (p34^cdc2/cyclinB), E (ERK2), or J (JNK3). Note that GST-1.1 is phosphorylated preferentially by JNK3 (lane 3).