FIG. 5.

MAPK signaling stimulates Mos mRNA polyadenylation and translation in the absence of MPF activity. Immature oocytes were injected with RNA encoding GST 107Wee, as indicated, and left for 14 h to express the protein. The oocytes were then either stimulated with progesterone (Prog) or injected with RNA encoding GST Mos. Pools of oocytes were taken when the controls were at GVBD₅₀ (progesterone at 4.5 h and GST Mos at 8 h). Protein lysates and total RNA were prepared from the same experiment. (A) Mos protein accumulation (top panel) and kinase activities (middle panels) are as described in the legend to Fig. 1. Expression of the GST-tagged proteins (bottom panel) was verified by Western blotting with GST antisera. The open arrowhead shows the position of GST 107Wee, and the solid arrowhead shows the position of GST Mos. (B) UTRX polyadenylation was analyzed as described in the legend to Fig. 2.