large ribosomal subunit

GO:0015934 · Ribonucleoprotein · Ribonucleoprotein complex · Proposed

The larger of the two subunits of a ribosome. Two sites on the ribosomal large subunit are involved in translation, namely the aminoacyl site (A site) and peptidyl site (P site). [GO:0015934]

Synonyms: ribosomal large subunit

Part of: ribosome (GO:0005840)

UniProt location names: UniProt Consortium, CC BY 4.0. Reference label and route sources.

Components

Component	Type	Part of / acts on	Grounding	Stoichiometry	Essential	Role
major large-subunit rRNA	Rna	part of	Reviewed label only (reviewed name; no accession asserted)	1	ESSENTIAL	Catalytic rRNA scaffold of the large ribosomal subunit that forms the peptidyl transferase center. `DOI:10.1126/science.289.5481.920` Nissen et al. 2000 located the Haloarcula marismortui 50S peptidyl transferase center in 23S rRNA. `DOI:10.1126/science.289.5481.905` Ban et al. 2000 resolved the Haloarcula marismortui 50S large subunit with 23S and 5S rRNAs in the RNA core.
5S rRNA	Rna	part of	`SO:0000652`	1 in archaeal and bacterial 50S subunits	CONDITIONAL	Small structural RNA of the large-subunit central protuberance. `DOI:10.1126/science.289.5481.905` Ban et al. 2000 resolved 5S rRNA within the Haloarcula marismortui 50S large-subunit central protuberance.
large-subunit ribosomal proteins	Protein	part of	Reviewed label only (reviewed name; no accession asserted)	33 proteins in Escherichia coli	CONDITIONAL	Proteins that bind and stabilize the folded large-subunit rRNA scaffold to form a functional peptidyl-transferase subunit. `DOI:10.1126/science.289.5481.905` Ban et al. 2000 describe proteins decorating the Haloarcula marismortui 50S rRNA surface. `DOI:10.1128/MMBR.00013-07` Kaczanowska and Ryden-Aulin 2007 report 33 protein constituents for the Escherichia coli 50S subunit.

Canonical examples

NCBITaxon:2238 Haloarcula marismortui — Archaeal source of the 2.4 A 50S large-subunit crystal structure that resolved the 23S/5S rRNA core and its ribosomal proteins. [DOI:10.1126/science.289.5481.905]
NCBITaxon:83333 Escherichia coli K-12 — Reference bacterial strain for the curated Complex Portal 50S large ribosomal subunit composition, CPX-3807. [ComplexPortal:CPX-3807]

Functions

peptidyltransferase activity GO:0000048 — The 50S peptidyl transferase center forms peptide bonds on the large-subunit rRNA scaffold during translation.
- DOI:10.1126/science.289.5481.920 Nissen et al. 2000 showed that the peptidyl transferase center of the 50S subunit is made entirely of RNA.

Mechanism graphs

50S peptidyl transferase center forms peptide bonds (FUNCTION)

In the archaeal 50S subunit, large-subunit rRNA forms a peptidyl transferase center where peptide bonds are made.

Subject	Predicate	Object	Evidence
major large-subunit rRNA	forms peptidyl transferase center of	large ribosomal subunit	`DOI:10.1126/science.289.5481.920` Nissen et al. 2000 localized all 50S peptidyl-transferase-center contacts to 23S rRNA.

Discussions

CURATION_TODO (OPEN): Split exact large-subunit rRNA and protein families across bacterial, archaeal, eukaryotic, and organellar ribosomes. The cross-lineage GO:0015934 term covers homologous large ribosomal subunits with different catalytic rRNAs, 5S or 5.8S-family RNAs, and many distinct ribosomal protein families. This first standalone record keeps the composition at coarse reviewed-label-only granularity until each exact source-neutral family is split and grounded.
INTERPRETATION (RESOLVED): Keep ComplexPortal:CPX-3807 scoped to the E. coli 50S source composition instead of making it an equivalent xref. ComplexPortal:CPX-3807 is the Escherichia coli K-12 50S large ribosomal subunit composition, whereas GO:0015934 denotes large ribosomal subunits across bacteria, archaea, eukaryotes, and organelles.

Evidence

GO:0015934 Gene Ontology cellular-component term for the large ribosomal subunit.
GO:0005840 Gene Ontology cellular-component term for the containing ribosome.
DOI:10.1126/science.289.5481.905 Ban et al. 2000, The complete atomic structure of the large ribosomal subunit at 2.4 A resolution, Science.
DOI:10.1126/science.289.5481.920 Nissen et al. 2000, The structural basis of ribosome activity in peptide bond synthesis, Science.

Curation history

2026-09-15T18:27:08Z codex · CREATED_RECORD — Scaffolded by scripts/new_record.py
2026-09-15T18:28:40Z codex · EXPANDED_RECORD — Added GO synonymy, ribosome parthood, broad catalytic rRNA and protein-cohort components, Haloarcula and E. coli exemplars, peptide bond formation function, GO/literature evidence, a 50S peptidyl transferase graph, and component-grounding and CPX-3807 scope discussions.
2026-09-15T18:36:34Z codex · REVIEW_FIX — Resolved PR #1012 review issues #1013 and #1014 by adding a grounded 5S rRNA constituent, attaching the component-splitting TODO to it, and removing the redundant peptidyltransferase activity graph node and large-subunit activity edge.

Source: data/structures/ribonucleoprotein/large_ribosomal_subunit.yaml