U4/U6 snRNP

GO:0071001 · Ribonucleoprotein · Ribonucleoprotein complex · Proposed

A ribonucleoprotein complex that contains the extensively base paired small nuclear RNAs U4 and U6, a heptameric ring of Sm proteins associated with U4, the Lsm2-8 heptameric ring complex associated with U6, as well as several proteins that are unique to the U4 snRNP or U6 snRNPs, some of which remain associated with the U4/U6 snRNA both while the U4 snRNP is free or assembled into a series of spliceosomal complexes. [GO:0071001]

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
U4 snRNP	Protein complex	part of	`GO:0005687`				U4 small nuclear ribonucleoprotein subcomplex that contributes U4 snRNA, its Sm protein ring and U4-associated proteins to U4/U6 snRNP. `GO:0071001` GO:0071001 defines the U4/U6 snRNP as containing small nuclear RNA U4, a U4-associated heptameric Sm ring and U4- or U6-specific proteins. `GO:0005687` GO:0005687 is the Gene Ontology cellular-component term for the U4 snRNP.
U6 snRNP	Protein complex	part of	`GO:0005688`				U6 small nuclear ribonucleoprotein subcomplex that contributes U6 snRNA, its Lsm2-8 ring and U6-associated proteins to U4/U6 snRNP. `GO:0071001` GO:0071001 defines the U4/U6 snRNP as containing small nuclear RNA U6, a U6-associated Lsm2-8 heptameric ring and U4- or U6-specific proteins. `GO:0005688` GO:0005688 is the Gene Ontology cellular-component term for the U6 snRNP.

Taxonomic distribution

NCBITaxon:4932 Saccharomyces cerevisiae — COMMON: The U4/U6 snRNP subcomplex is represented in budding-yeast U4/U6.U5 tri-snRNP cryo-EM structures; broader eukaryotic distribution is left for follow-up curation. [DOI:10.1038/nature16940]

Canonical examples

NCBITaxon:4932 Saccharomyces cerevisiae — Budding-yeast model whose U4/U6 small nuclear RNAs and associated U4/U6 snRNP proteins were resolved inside U4/U6.U5 tri-snRNP cryo-EM structures. [DOI:10.1038/nature16940]

Mechanism graphs

U4 and U6 snRNP constituents define the U4/U6 snRNP (ASSEMBLY)

The U4/U6 snRNP contains extensively base-paired U4 and U6 small nuclear RNAs together with the U4-associated Sm ring, the U6-associated Lsm2-8 ring and U4/U6-associated proteins.

Subject	Predicate	Object	Evidence
U4 snRNP	contributes constituents to	U4/U6 snRNP	`GO:0071001` GO:0071001 defines the U4/U6 snRNP as containing small nuclear RNA U4 and a heptameric ring of Sm proteins associated with U4.
U6 snRNP	contributes constituents to	U4/U6 snRNP	`GO:0071001` GO:0071001 defines the U4/U6 snRNP as containing small nuclear RNA U6 and the Lsm2-8 heptameric ring associated with U6.

Discussions

CURATION_TODO (OPEN): Resolve exact source-neutral groundings for the Sm ring, Lsm2-8 ring, Prp3, Prp4, Prp31 and other protein families that form the U4/U6 snRNP. The first GO:0071001 record captures the U4 and U6 snRNP subcomplexes at GO-grounded granularity. Individual ribonucleoprotein rings and U4/U6-specific protein-family boundaries should be resolved before splitting this inventory.

Evidence

GO:0071001 Gene Ontology cellular-component term for the U4/U6 snRNP.
GO:0097525 Gene Ontology cellular-component parent term for spliceosomal snRNP complex.
GO:0005687 Gene Ontology cellular-component term for the U4 snRNP.
GO:0005688 Gene Ontology cellular-component term for the U6 snRNP.
DOI:10.1038/nature14548 Nguyen, Galej, Bai and colleagues 2015, The architecture of the spliceosomal U4/U6.U5 tri-snRNP, Nature.
PMID:26106855 PubMed identifier for Nguyen, Galej, Bai and colleagues 2015 as reported by PubMed.
DOI:10.1038/nature16940 Nguyen, Galej, Bai and colleagues 2016, Cryo-EM structure of the yeast U4/U6.U5 tri-snRNP at 3.7 Angstrom resolution, Nature.
PMID:26829225 PubMed identifier for Nguyen, Galej, Bai and colleagues 2016 as reported by PubMed.

Curation history

2026-09-24T14:00:48Z codex · CREATED_RECORD — Scaffolded by scripts/new_record.py
2026-09-24T14:01:43Z codex · EXPANDED_RECORD — Added spliceosomal snRNP parentage, GO-grounded U4 and U6 snRNP components, budding-yeast distribution, Nguyen/Galej/Nagai yeast U4/U6.U5 tri-snRNP cryo-EM evidence, a minimal U4/U6 assembly graph and a protein-component grounding TODO.
2026-09-24T14:16:41Z codex · ADDRESS_REVIEW — #1495: reworded the U4/U6 graph from a subcomplex assembly transition to GO-defined constituent contributions; #1496: trimmed record-level GO evidence notes for U4 and U6 snRNP so component exact synonyms are not implied to be U4/U6 snRNP aliases.

Source: data/structures/ribonucleoprotein/u4_u6_snrnp.yaml