Translation termination factor eRF3; has a role in mRNA deadenylation and decay; altered protein conformation creates the [PSI(+)] prion, self-perpetuating amyloid fibrils that modify cellular fitness, alter translational fidelity by affecting reading frame selection, and result in a nonsense suppressor phenotype; forms reversible liquid condensates in response to both acidic and osmotic stress to promote survival; many stress-response genes are repressed in the presence of [PSI(+)]