preribosome, large subunit precursor

GO:0030687 · Ribonucleoprotein · Ribonucleoprotein complex · Proposed

A preribosomal complex consisting of 27SA, 27SB, and/or 7S pre-rRNA, 5S rRNA, ribosomal proteins including late-associating large subunit proteins, and associated proteins; a precursor of the eukaryotic cytoplasmic large ribosomal subunit. [GO:0030687]

Synonyms: 66S preribosome

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

Components

Component	Type	Part of / acts on	Grounding	Genes	Stoichiometry	Essential	Role
large-subunit preribosome RNA cohort	Rna	part of	Reviewed label only (reviewed name; no accession asserted)				27SA, 27SB and/or 7S precursor rRNAs plus 5S rRNA assembled into a eukaryotic cytoplasmic large-subunit preribosomal precursor. `GO:0030687` GO:0030687 defines the large-subunit precursor preribosome as containing 27SA, 27SB and/or 7S pre-rRNA with 5S rRNA. `SO:0002393` SO:0002393 denotes the broader precursor_RNA class, not specific large-subunit precursor rRNA species.
large-subunit preribosome protein cohort	Protein	part of	Reviewed label only (reviewed name; no accession asserted)				Ribosomal proteins and associated assembly factors carried by eukaryotic large-subunit preribosome precursors. `GO:0030687` GO:0030687 defines the large-subunit precursor preribosome as containing ribosomal proteins, including late-associating large-subunit ribosomal proteins, and associated proteins.

Taxonomic distribution

NCBITaxon:4932 Saccharomyces cerevisiae — COMMON: GO:0030687 notes that this large-subunit precursor preribosome is a 66S complex in Saccharomyces; broader eukaryotic distribution is left for a follow-up curation pass. [GO:0030687]

Canonical examples

NCBITaxon:4932 Saccharomyces cerevisiae — Budding yeast is the model for the 66S large-subunit preribosome precursor described in the GO:0030687 comment. [GO:0030687]

Functions

ribosomal large subunit biogenesis GO:0042273 — As a precursor of the eukaryotic cytoplasmic large ribosomal subunit, the large-subunit preribosome participates in large-subunit biogenesis.
- GO:0042273 GO:0042273 is the Gene Ontology biological-process term for ribosomal large subunit biogenesis.
- GO:0030687 GO:0030687 defines this preribosome as a precursor of the eukaryotic cytoplasmic large ribosomal subunit.
ribosome biogenesis GO:0042254 — The large-subunit preribosome is a preribosomal complex formed as part of the broader ribosome-biogenesis program.
- GO:0042254 GO:0042254 is the Gene Ontology biological-process term for ribosome biogenesis.
- GO:0030684 GO:0030684 defines preribosomal complexes as being formed during ribosome biogenesis.

Mechanism graphs

RNA and protein cohorts form large-subunit preribosome precursors (ASSEMBLY)

GO defines the large-subunit precursor preribosome as a preribosomal complex containing large-subunit precursor rRNAs, 5S rRNA, ribosomal proteins including late-associating large-subunit proteins, and associated proteins.

Subject	Predicate	Object	Evidence
large-subunit preribosome RNA cohort	contributes constituents to	preribosome, large subunit precursor	`GO:0030687` GO:0030687 defines the complex as containing 27SA, 27SB and/or 7S pre-rRNA with 5S rRNA.
large-subunit preribosome protein cohort	contributes constituents to	preribosome, large subunit precursor	`GO:0030687` GO:0030687 defines the complex as containing ribosomal proteins and associated proteins.
preribosome, large subunit precursor	participates in	ribosomal large subunit biogenesis	`GO:0030687` GO:0030687 defines this preribosome as a precursor of the eukaryotic cytoplasmic large ribosomal subunit. `GO:0042273` GO:0042273 is the process term for ribosomal large subunit biogenesis.

Discussions

CURATION_TODO (OPEN): Resolve exact large-subunit preribosome precursor RNA, ribosomal-protein and associated assembly-factor boundaries. GO:0030687 defines a eukaryotic cytoplasmic large-subunit preribosome precursor with 27SA, 27SB and/or 7S pre-rRNA, 5S rRNA, ribosomal proteins including late-associating large-subunit proteins, and associated proteins. Exact source-neutral boundaries for those precursor RNAs and protein cohorts need narrower literature-backed curation.

Evidence

GO:0030687 Gene Ontology cellular-component term for the preribosome, large subunit precursor and its 66S preribosome narrow synonym.
GO:0030684 Gene Ontology cellular-component parent term for preribosomal complexes.
GO:0042273 Gene Ontology biological-process term for ribosomal large subunit biogenesis.
GO:0042254 Gene Ontology biological-process term for ribosome biogenesis.
SO:0002393 Sequence Ontology term for the broader precursor_RNA class, which is not specific to large-subunit precursor rRNAs.
SO:0000652 Sequence Ontology term for 5S_rRNA, which covers one RNA in the GO:0030687 precursor-rRNA cohort but not the full RNA cohort.
PMID:10567516 PubMed identifier for Kressler, Linder and de la Cruz 1999, the review publication cited in the GO:0030687 definition.
DOI:10.1128/MCB.19.12.7897 DOI for Kressler, Linder and de la Cruz 1999, 'Protein trans-Acting Factors Involved in Ribosome Biogenesis in Saccharomyces cerevisiae', verified through NCBI E-utilities.

Curation history

2026-09-25T19:33:37Z codex · CREATED_RECORD — Scaffolded by scripts/new_record.py
2026-09-25T19:34:23Z codex · EXPANDED_RECORD — Added 66S preribosome synonymy, preribosome parentage, reviewed-label-only large-subunit preribosome RNA and protein cohorts, a conservative budding-yeast example, ribosomal large-subunit biogenesis functions, GO/SO/PubMed evidence, a nonmechanistic constituent graph and a TODO for exact component boundaries.
2026-09-25T19:44:40Z codex · ADDRESS_REVIEW — Resolved PR #1598 review issue #1599 by renaming the large-subunit preribosome RNA cohort component so it no longer implies that mature 5S rRNA is a precursor rRNA.

Source: data/structures/ribonucleoprotein/preribosome_large_subunit_precursor.yaml