Fig. 4. Determination of nos-2 3'UTR regions that are critical for interaction with the various proteins. (A) Schematic illustration of the five regions of nos-2 3'UTR that were mutated by substitution. SubA begins immediately downstream of the stop codon. (B-E) Electrophoretic mobility shifts of various mutant versions of radiolabeled nos-2 3'UTR by MBP:MEX-3 (B), GST:SPN-4 (C) and GST:OMA-2 (D,E). The first lane in each set is the mobility of RNA in the absence of protein. Radiolabeled RNA used in D contained the wild-type version of the following regions only: 1, SubA-C; 2, SubB-E; 3, SubA-D; 4, SubD-E, whereas those in other panels contained the 200 bp nos-2 3'UTR with the indicated regions substituted with (TG)₁₅. WT in all panels indicate the wild-type version of the 200 bp nos-2 3'UTR. (F) Binding of radiolabeled WT and mutant nos-2 3'UTR RNA to solid matrix in presence of the indicated components (see Materials and methods for details). L RNA, radiolabeled RNA; UL RNA, unlabeled RNA.