Involved in translation termination. Stimulates the activity of ERF1. Binds guanine nucleotides. Recruited by polyadenylate-binding protein PAB1 to poly(A)-tails of mRNAs. Interaction with PAB1 is also required for regulation of normal mRNA decay through translation termination-coupled poly(A) shortening. Heterodimer of two subunits, one of which binds GTP. Interacts with polyadenylate-binding protein PAB1, and TPA1. The prion domain (PrD) is a Gln/Asn (Q/N)-rich domain, which is unstructured in its native, soluble form, and which forms a parallel in-register beta-sheet in its amyloid form. [PSI+] is the prion form of SUP35 (PubMed:8978027). [PSI+] is the result of a conformational change of the cellular SUP35 protein that becomes self-propagating and infectious. This conformational change generates a form of SUP35 that assembles into amyloid fibrils. [PSI+]-aggregates sequester soluble SUP35, resulting in defects in faithful translation termination by read-through of translation termination codons (PubMed:8670813). [PSI+] can be cured by GdnHCl and by deletion of the molecular chaperone HSP104, which is required for [PSI+] propagation (PubMed:9335589). It is speculated that the prion form would be at least mildly deleterious in most environments, but it might sometimes increase evolvability in certain harsh environments (PubMed:19917766). Present with 78900 molecules/cell in log phase SD medium. Belongs to the TRAFAC class translation factor GTPase superfamily. Classic translation factor GTPase family. ERF3 subfamily.