Figure 1.

Xenopus CPEB recognizes the mouse c-mos CPEs. (A) Polyadenylylation of c-mos mRNA 3′-UTR in Xenopus egg extracts. Radiolabeled c-mos 3′-UTR was incubated with egg extracts that were untreated (control), mock-depleted (preimm), or immunodepleted of CPEB (anti-XCPEB, αXCPEB). The RNA was then extracted and analyzed for polyadenylylation by denaturing gel electrophoresis and autoradiography. Polyadenylylation assays were performed with wild-type RNA (lanes 1–4) or a mutant RNA that lacked CPEs (lanes 5 and 6). (B) Gel mobility-shift assay with His-tagged XCPEB. Radiolabeled wild-type (lanes 1–3) or cpe− (lanes 4–6) c-mos 3′-UTR was incubated with protein preparations from bacteria expressing (lanes 3 and 6) or lacking (lanes 2 and 5) XCPEB or was incubated without protein (lanes 1 and 4). The RNA was resolved in a 4% polyacrylamide gel containing 1 M urea.