Fig. 3. MEX-3, SPN-4, OMA-1, OMA-2 and POS-1 physically interact with nos-2 3'UTR. (A) Electrophoretic mobility patterns of radiolabeled 200 bp nos-2 3'UTR RNA in the presence of MBP:MEX-3 (M), GST:SPN-4 (S), GST:OMA-1 (O1) and GST:OMA-2 (O2). L nos-2, radiolabeled 200 bp nos-2 3'UTR; UL nos-2, unlabeled nos-2 3'UTR; NS RNA, unlabeled non-specific RNA; 5x, 10x and 50x, number of times molar excess over L nos-2. (B) Electrophoretic mobility shift with GST:POS-1. Three different concentrations of GST-POS-1 were used: 75, 350 and 200 ng/µl. Comparison of lanes 2-4 indicates multimerization of this protein-RNA complex at higher protein concentrations. (C) Binding of radiolabeled nos-2 3'UTR RNA to solid matrix in presence of the indicated components (see Materials and methods for details).