Fig. 5. CE¹⁶ RNA affinity isolation of candidate silencer protein(s). (A) Coomassie Blue stain of proteins eluted from CE¹⁶ RNA after incubation in HeLa nuclear extract. Bands of ∼33–35 kDa are hnRNP A/B proteins (lane 1) as identified by nanospray mass spectrometry. SA, streptavidin from magnetic beads. Lane 2 shows molecular weight standards. (B) Western blot analysis of HeLa nuclear extract (lanes 3 and 6) and of proteins eluted from CE¹⁶ and control RNAs performed with antibody against hnRNP A1/A1^B (lanes 3–5) and hnRNP A2/B1 proteins (lanes 6–8). (C) Western blot of proteins eluted from biotinylated CE¹⁶ and silencer mutant RNAs performed with antibodies against hnRNP A1 and A2.