Using selection-amplification, we have isolated RNAs
with affinity for translation termination factors eRF1
and eRF1[bull ]eRF3 complex. Individual RNAs not only
bind, but inhibit eRF1-mediated release of a model nascent
chain from 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[bull ]eRF3 interactions.
Finally, four RNA inhibitors of release suppress a UAG
stop codon in mammalian extracts dependent for termination
on eRF1 from several metazoan species. These RNAs are therefore
new specific inhibitors for the analysis of eukaryotic
termination, and potentially a new class of omnipotent
termination suppressors with possible therapeutic significance.