Suppression of eukaryotic translation termination by selected RNAs

Using selection-amplification, we have isolated RNAs with affinity for tran slation termination factors eRF1 and eRF1(.)eRF3 complex, Individual RNAs n ot only bind, but inhibit eRf1-mediated release of a model nascent chain fr om eukaryotic ribosomes, There is also significant but weaker inhibition of eRF1-stimulated eRF3 GTPase and eRF3 stimulation of eRF1 release activity, These latter selected RNAs therefore hinder eRF1(.)eRF3 interactions, Fina lly, four RNA inhibitors of release suppress a UAG stop codon in mammalian extracts dependent for termination on eRF1 from several metazoan species. T hese RNAs are therefore new specific inhibitors for the analysis of eukaryo tic termination, and potentially a new class of omnipotent termination supp ressors with possible therapeutic significance.