The mammalian large ribosomal subunit (60S) is the larger subunit of the mammalian 80S ribosomes, with the other major component being the small ribosomal subunit (40S). The 60S subunit consists of a 28S ribosomal RNA (rRNA), a 5.8S rRNA, a short 5S rRNA, and ~47 ribosomal proteins. The 60S subunit catalyzes peptide bond formation and contains the nascent polypeptide exit tunnel.