A novel, RNA-containing splicing factor is purified on the basis of its physical interaction with a previously known subunit of the spliceosome. You sequence the RNA within the new factor, and identify a region that is perfectly complementary to a stretch of the RNA from the previously known subunit with which it interacts. You suspect that the interaction between the new factor and the subunit is mediated by hybridization between these complementary RNA sequences, but would like to be sure. How could you test this experimentally

The systematic evolution of ligands by exponential enrichment (SELEX) is a widely used technique in molecular biology to produce specific small DNA/RNA fragments (aptamers) that interact with target molecules. RNA-RNA SELEX can be used to determine the specificity of RNA-RNA interactions. The RNA-RNA SELEX technique involves generating an aptamer RNA library. Subsequently, these RNA aptamers are exposed to the target molecule (in this case spliceosome). Finally, RNA sequences that don't bind to the target molecule can be eliminated by using affinity chromatography, thus identifying RNA-RNA hybridization sites at the target molecule.