Dimeric CPEBs do not cross-link to RNA. (A) Dimeric form of CPEB, i.e., tandem CPEB-CPEB and coiled-coil CPEB, were ectopically expressed in oocytes. The endogenous CPEB from the same lysate cross-linked to CPE-containing 32P-labeled RNA, while the dimeric CPEBs showed virtually no label transfer from the RNA. CPE2/1/0, radiolabeled RNA containing 2/1/0 CPE(s), CPE1 ×2, twice amount of CPE1 RNA that provides the same number of CPEs as CPE2 RNA in the cross-linking reaction. (B) Nontreated oocyte lysate was cross-linked to the radiolabeled RNA and analyzed on a mild denaturing SDS-PAGE. Although the dimeric CPEB was obvious on the Western blot, no corresponding cross-linking signal was detected by autoradiography.
