Directs the termination of nascent peptide synthesis (translation) in response to the termination codons UAA, UAG and UGA (PubMed:7990965, PubMed:24486019). Component of the transient SURF complex which recruits UPF1 to stalled ribosomes in the context of nonsense-mediated decay (NMD) of mRNAs containing premature stop codons. Required for SHFL-mediated translation termination which inhibits programmed ribosomal frameshifting (-1PRF) of mRNA from viruses and cellular genes (PubMed:30682371). Heterodimer of two subunits, one of which binds GTP (PubMed:19417104). Component of the transient SURF (SMG1-UPF1-eRF1-eRF3) complex (PubMed:19417104). Interacts with JMJD4 (PubMed:24486019). The ETF1-GSPT1 complex interacts with JMJD4 (PubMed:24486019). Methylated at Gln-185 by N6AMT1. Hydroxylation at Lys-63 by JMJD4 promotes its translational termination efficiency. Belongs to the eukaryotic release factor 1 family.