Directs the termination of nascent peptide synthesis (translation) in response to the termination codons UAA, UAG and UGA (PubMed:7990965). 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 (By similarity). Required for SHFL-mediated translation termination which inhibits programmed ribosomal frameshifting (-1PRF) of mRNA from viruses and cellular genes. Heterodimer of two subunits, one of which binds GTP (By similarity). Component of the transient SURF (SMG1-UPF1-eRF1-eRF3) complex (By similarity). Belongs to the eukaryotic release factor 1 family.