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. 2004 Apr 1;18(7):755–768. doi: 10.1101/gad.286404

Figure 2.

Figure 2.

Tethered SR proteins stimulate translation in Xenopus oocytes. (A) mRNAs encoding either the MS2 protein alone, or fusions between MS2-U1A, MS2-SF2/ASF, and MS2-PABP were coinjected into the cytoplasm of Xenopus oocyctes with a luciferase reporter mRNA containing MS2p-binding sites within its 3′UTR and a β-galactosidase mRNA lacking MS2-binding sites. The injected fusion proteins did not significantly affect β-galactosidase levels and nonspecific effects of the fusion proteins on translation were taken into account by normalizing luciferase activity to β-galactosidase activity. These data represent the average stimulation from three independent experiments. (B) Northern blot analysis showing constant levels of mRNA reporter upon injection of MS2-U1A (lanes 1,2) and MS2-SF2/ASF (lanes 3,4). (t) Time after injection (0 and 16 h, respectively). (C) The effect of the MS2-SF2/ASF fusion protein is specific to reporter mRNAs containing cognate MS2-binding sites. Microinjection experiments were performed using a luciferase reporter mRNA containing (white bars) or lacking (black bars) functional MS2-binding sites. (D) The RS domain of SR proteins is sufficient to stimulate translation in vivo. mRNAs encoding MS2, MS2-U1A, MS2-SF2/ASF, MS2-SF2 FF-DD, MS2-RS SF2/ASF, or MS2-RS SC35 were injected into the cytoplasm of Xenopus oocytes along with reporter mRNAs as described above. These data represents the average stimulation from three independent experiments.