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.