FIG. 7.
Polyadenylation and cap methylation stimulate translation synergistically in maturing oocytes. (A) Schematic diagram of mRNAs. LUC/B1wt and LUC/B1mut mRNAs were prepared and manipulated in oocytes as described in the text. LUC/B1wt carries AAUAAA, while LUC/B1mut carries AAgAAA. (B) N-7 methylation of the cap and polyadenylation stimulate translation. The y axis indicates luciferase activity (arbitrary units, corrected for the amount of mRNA injected). Each value is an average of two samples (five oocytes each) which were incubated in the absence or presence of progesterone, as indicated. The ratio of luciferase activity observed in mature versus nonmature oocytes (+P/−P) is indicated. (C) Comparison of mRNA stability. mRNAs were analyzed as described in the text. Samples were taken immediately following injection (lanes 1, 4, 7, and 10), following incubation in the absence of progesterone (lanes 2, 5, 8, and 11), or following incubation in the presence of progesterone (lane 3, 6, 9, and 12).