Figure 3.
Synergistic activation of JNK1 and ERK2 by Ras-GRF1 and Gβγ. (A) Effect of dominant-negative small GTP-binding proteins on Ras-GRF1 and Gβγ-induced JNK1 activation. Activities of HA-tagged JNK1 immunoprecipitated from 293 cells expressing indicated proteins were assessed. Relative values compared with the activity from Ras-GRF1 plus Gβγ-expressing cells are shown as mean ± SE (n = 3). (B) Effect of DH domain mutation and deletion of the amino-terminal PH domain of Ras-GRF1 on Ras-GRF1 and Gβγ-induced JNK1 activation. Activities of HA-tagged JNK1 immunoprecipitated from 293 cells expressing indicated proteins were assessed. Relative values compared with the activity from mock-transfected cells are shown as mean ± SE (n = 3). (C) Effect of dominant-negative small GTP-binding proteins on Ras-GRF1 and Gβγ-induced ERK2 activation. Activities of HA-tagged ERK2 immunoprecipitated from 293 cells expressing indicated proteins were assessed. Data are shown as described in A. (D) Effect of DH domain mutation and deletion of the amino-terminal PH domain of Ras-GRF1 on Ras-GRF1 and Gβγ-induced ERK2 activation. Activities of HA-tagged ERK2 immunoprecipitated from 293 cells expressing indicated proteins were assessed. Data are shown as described in B.