Fig. 1. Isolation of Drosophila Rump by tandem RNA-affinity purification. (A) TRAP-tagged RNAs with the streptavidin-binding S1 aptamer and six tandem copies of the MS2 stem-loop (MS2x6). TRAP+2'-3X RNA contains three tandem copies of the nos +2' localization element, whereas the TRAP-ctrl RNA contains transcribed vector sequence. (B) SYPRO Ruby-stained SDS-PAGE gel showing the final RNase eluates from purifications performed in parallel with TRAP+2'-3X and TRAP-ctrl RNAs. The protein band enriched for Rump is marked with an asterisk. The faint band of similar size in the control purification contains contaminating E. coli Hsp70. GST-MCP that elutes non-specifically is marked with an arrowhead. To permit comparison between the two samples, the amount of protein eluate loaded was adjusted according to the pre-elution RNA recovery for each sample. Molecular mass standards are indicated in kDa.