60s

60S is the large subunit of the cytoplasmic eukaryotic ribosome. In most eukaryotes, the 60S subunit pairs with the small 40S subunit to form the 80S ribosome, the molecular machine that synthesizes proteins. The designation 60S distinguishes the eukaryotic large subunit from prokaryotic large subunits such as the bacterial 50S.

Composition and structure: The 60S subunit comprises ribosomal RNA and ribosomal proteins. Its RNA components include 28S, 5.8S, and 5S rRNA, which together form the catalytic core and structural framework. The subunit also contains numerous ribosomal proteins; in humans the 60S subunit includes about 46 ribosomal proteins. These components assemble into functional centers that coordinate translation.

Function: During translation, the 60S subunit participates in peptide bond formation at the peptidyl transferase center and provides binding sites for transfer RNA and translation factors. It forms the peptidyl transferase center and the polypeptide exit tunnel, enabling synthesis and egress of the growing polypeptide. The 60S works in concert with the 40S subunit to ensure correct decoding, translocation, and proofreading during elongation and termination.

Biogenesis and maturation: Ribosome assembly begins in the nucleolus with transcription and processing of rRNA and the import or synthesis of ribosomal proteins. Large subunit assembly involves the formation of pre-60S particles, maturation steps in the nucleus, and eventual export to the cytoplasm where final maturation occurs before participation in translation.

Clinical and research notes: Defects in 60S biogenesis or mutations in ribosomal protein genes can contribute to ribosomopathies and other disorders. Certain inhibitors, such as cycloheximide, target the eukaryotic 60S subunit to block translation, and are used in laboratory research to study ribosome function.