ribosome

GO:0005840 · RIBONUCLEOPROTEIN · RIBONUCLEOPROTEIN_COMPLEX · PROPOSED

The ribonucleoprotein particle that translates mRNA into protein. The bacterial (70S) ribosome comprises a small (30S) subunit built on 16S rRNA, which decodes the mRNA, and a large (50S) subunit built on 23S and 5S rRNA, whose 23S rRNA catalyses peptide bond formation. Archaeal and eukaryotic cytosolic ribosomes are homologous but larger. [GO:0005840]

Rendering of the cryo-EM structure of a Psychrobacter urativorans 70S ribosome in complex with the hibernation factors Balon and RaiA (PDB 8RD8). A model derived from the cryo-EM map, not a raw micrograph. CRYO_EM · *Psychrobacter urativorans* (`NCBITaxon:45610`) · Helena-Bueno, K., Rybak, M.Y., Gagnon, M.G., Hill, C.H., Melnikov, S.V.; CC0, via Wikimedia Commons · CC0 · source: WIKIMEDIA_COMMONS File:P. urativorans 70S ribosome with Balon and RaiA.jpg (M149208035) · `DOI:10.1038/s41586-024-07041-8`

Synonyms: 70S ribosome

Has part: GO:0015935 GO:0015934

Components

Component	Type	Grounding	Genes	Stoichiometry	Essential	Role
16S rRNA (small-subunit rRNA)	RNA	`SO:0000650`	rrs	1	ESSENTIAL	Structural core of the 30S subunit; carries the decoding centre that monitors codon–anticodon pairing. `DOI:10.1038/35030006` Wimberly et al. 2000 report the 3.05 Å structure of the Thermus thermophilus 30S subunit, with 16S rRNA forming the body, platform and head.
23S rRNA (large-subunit rRNA)	RNA	`SO:0000651`	rrl	1	ESSENTIAL	Structural core of the 50S subunit; forms the peptidyl transferase centre. `DOI:10.1126/science.289.5481.920` Nissen et al. 2000 show the peptidyl transferase centre of the Haloarcula marismortui 50S subunit is composed entirely of RNA — the ribosome is a ribozyme.
5S rRNA	RNA	`SO:0000652`	rrf	1	ESSENTIAL	Small RNA of the 50S central protuberance. `DOI:10.1126/science.289.5481.905` Ban et al. 2000 resolve 5S rRNA within the 2.4 Å structure of the H. marismortui large subunit.
small-subunit ribosomal proteins (uS2–uS21, bS6, bS16, bS18, bS20, bS21)	PROTEIN	REVIEWED_LABEL_ONLY		~21 in Escherichia coli	CONDITIONAL	Stabilise 16S rRNA folding; several are individually dispensable. `DOI:10.1038/35030006` Wimberly et al. 2000 place 20 proteins in the T. thermophilus 30S structure, mostly on the solvent-exposed surface.
large-subunit ribosomal proteins (uL1–uL30, bL9, bL12, bL17…)	PROTEIN	REVIEWED_LABEL_ONLY		~33 in Escherichia coli	CONDITIONAL	Stabilise 23S/5S rRNA; bL12 stalk recruits translation GTPases. `DOI:10.1126/science.289.5481.905` Ban et al. 2000 describe the protein complement of the large subunit and its distribution over the rRNA surface.

Taxonomic distribution

NCBITaxon:2 Bacteria — UNIVERSAL: 70S form. [DOI:10.1038/nature08403]
NCBITaxon:2157 Archaea — UNIVERSAL: 70S sedimentation but with additional proteins; the large-subunit structure of H. marismortui is the archetypal high-resolution model. [DOI:10.1126/science.289.5481.905]
NCBITaxon:2759 Eukaryota — UNIVERSAL: Cytosolic 80S ribosome; this record covers the bacterial/archaeal 70S form and the shared core. [DOI:10.1038/nature08403]
NCBITaxon:45610 Psychrobacter urativorans — UNIVERSAL: Organism of the hosted cryo-EM structure (PDB 8RD8), a dormant 70S ribosome bound by hibernation factors Balon and RaiA. [DOI:10.1038/s41586-024-07041-8]

Canonical examples

NCBITaxon:274 Thermus thermophilus — Source of the first complete 70S and 30S crystal structures. [DOI:10.1126/science.1060089]
NCBITaxon:83333 Escherichia coli K-12 — The genetic and biochemical reference system for bacterial translation. [DOI:10.1038/nature08403]

Functions

translation GO:0006412 — Template-directed synthesis of polypeptides from mRNA.
- DOI:10.1038/nature08403 Schmeing & Ramakrishnan 2009 review how ribosome structures explain decoding, peptidyl transfer and translocation.
peptidyltransferase activity GO:0000048 — Peptide bond formation catalysed by 23S rRNA in the large subunit.
- DOI:10.1126/science.289.5481.920 Nissen et al. 2000 locate the catalytic site entirely within 23S rRNA.

Physical properties

SEDIMENTATION_COEFFICIENT: 70 (bacterial ribosome (Svedberg units)) [DOI:10.1126/science.1060089]
DIAMETER: ~20 UO:0000018 (intact 70S particle) [GO:0005840]
MOLECULAR_MASS: ~2500 UO:0000222 (Escherichia coli 70S) [DOI:10.1038/nature08403]

Mechanism graphs

How the ribosome makes a peptide bond and moves along the mRNA (FUNCTION)

Core elongation-cycle mechanism common to all ribosomes.

Subject	Predicate	Object	Evidence
small ribosomal subunit	decodes	mRNA codon	`DOI:10.1126/science.1060612` Ogle et al. 2001 show 16S rRNA bases A1492, A1493 and G530 flip out to read the minor groove of the codon–anticodon helix.
aminoacyl-tRNA	substrate of	peptidyltransferase activity	`DOI:10.1038/nature08403` Aminoacyl-tRNA in the A site donates its amino group to the peptidyl-tRNA ester in the P site.
23S rRNA peptidyl transferase centre	catalyses `RO:0002327`	peptidyltransferase activity	`DOI:10.1126/science.289.5481.920` Nissen et al. 2000, the ribozyme result.
elongation factor G	drives	ribosomal translocation	`DOI:10.1038/nature08403` Schmeing & Ramakrishnan 2009 summarise EF-G-driven translocation.
ribosomal translocation	occurs in `BFO:0000066`	ribosome	`DOI:10.1038/nature08403` Translocation is an intrinsic ribosomal motion accelerated by EF-G.

Discussions

CURATION_TODO (OPEN): Should each ribosomal protein family be its own component with an InterPro grounding, rather than the two paralogue-set components used here? Per-protein components are what ProteinTraitsMech can link to; the set-level components are a placeholder.

Evidence

DOI:10.1126/science.1060089 Yusupov et al. 2001 — 5.5 Å structure of the complete T. thermophilus 70S ribosome with mRNA and tRNAs.
DOI:10.1126/science.289.5481.905 Ban et al. 2000 — 2.4 Å structure of the H. marismortui large subunit.
DOI:10.1038/35030006 Wimberly et al. 2000 — structure of the T. thermophilus 30S subunit.

Curation history

2026-08-29T00:00:00Z claude · CREATED_RECORD — Drafted composition, distribution, functions and elongation-cycle mechanism graph from the cited structural literature. Not yet human-reviewed.
2026-08-29T01:00:00Z claude · FIX_REVIEW_FINDINGS — PR #1 review: removed unresolvable xref ComplexPortal:CPX-3802 (#2); molecular-mass unit UO:0000021 (gram) -> UO:0000222 (kilodalton) (#3); Ogle 2001 DOI corrected to 10.1126/science.1060612 (#4). Every CURIE and DOI in the record was resolved against OLS/Crossref.
2026-08-29T03:00:00Z claude · ADD_IMAGE — Added Commons CC0 rendering of PDB 8RD8 (P. urativorans 70S ribosome, cryo-EM, DOI:10.1038/s41586-024-07041-8); organism and citation verified via RCSB and Crossref. Added P. urativorans to taxonomic_distribution as the imaged organism.
2026-08-30T05:00:00Z claude · FIX_ID_LABEL_FINDINGS — Vendored id-label gate (#48): removed GO:0003735 from the two ribosomal-protein set components (a molecular-function term cannot ground a protein set); removed SO:0000651 from the peptidyl-transferase-centre node (a part, not the whole 23S rRNA); relabelled GO:0000048 uses to the canonical 'peptidyltransferase activity'.
2026-08-30T19:08:35Z fetch_commons_image · ADD_IMAGE — Updated Commons image File:P. urativorans 70S ribosome with Balon and RaiA.jpg (CC0, Psychrobacter urativorans); licence, attribution and taxon read from the Commons and Wikidata APIs at retrieval.
2026-08-30T19:11:14Z fetch_commons_image · ADD_IMAGE — Updated Commons image File:P. urativorans 70S ribosome with Balon and RaiA.jpg (CC0, Psychrobacter urativorans); licence, attribution and taxon read from the Commons and Wikidata APIs at retrieval.

Source: data/structures/ribonucleoprotein/ribosome.yaml