<p>Peptide chain release factor 3 increases the formation of ribosomal termination complexes and stimulates activity of RF-1 and RF-2. It binds to guanine nucleotides and has a strong preference for UGA stop codons. This translation releasing factor, RF-3 (prfC) was originally described as stopcodon-independent, in contrast to peptide chain release factor 1 (RF-1, prfA) and RF-2 (prfB). RF-1 and RF-2 are closely related to each other, while RF-3 is similar to elongation factors EF-Tu and EF-G; RF-1 is active at UAA and UAG and RF-2 is active at UAA and UGA. All bacteria and organelles have RF-1. The Mycoplasmas and organelles, which translate UGA as Trp rather than as a stop codon, lack RF-2. RF-3, in contrast, seems to be rare among bacteria and is found so far only in <taxon tax_id="562">Escherichia coli</taxon> and some other gamma subdivision Proteobacteria, in <taxon tax_id="1148">Synechocystis sp.</taxon> (strain PCC 6803), and in <taxon tax_id="1280">Staphylococcus aureus</taxon>.</p>