U6atac snRNP

GO:0005691 · Ribonucleoprotein · Ribonucleoprotein complex · Proposed

A ribonucleoprotein complex that contains small nuclear RNA U6atac, the Lsm2-8 heptameric ring complex, as well as several proteins that are unique to the U6atac snRNP, most of which remain associated with the U6atac snRNA both while the U6atac snRNP is free or assembled into the U4atac/U6atac snRNP or into a series of spliceosomal complexes. [GO:0005691]

Synonyms: snRNP U6atac

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
U6atac snRNA	Rna	part of	`SO:0000397`				U6atac small nuclear RNA constituent named in the U6atac snRNP definition and grounded to the U6atac snRNA Sequence Ontology term. `GO:0005691` GO:0005691 defines the U6atac snRNP as containing small nuclear RNA U6atac. `SO:0000397` SO:0000397 is the Sequence Ontology term for U6atac snRNA.
Lsm2-8 complex	Protein complex	part of	`GO:0120115`				Lsm2-8 heptameric ring complex constituent named in the U6atac snRNP definition. `GO:0005691` GO:0005691 defines the U6atac snRNP as containing the Lsm2-8 heptameric ring complex. `GO:0120115` GO:0120115 defines the Lsm2-8 complex as the heteroheptameric complex composed of Lsm2, Lsm3, Lsm4, Lsm5, Lsm6, Lsm7 and Lsm8 or their orthologs.

Taxonomic distribution

NCBITaxon:9606 Homo sapiens — COMMON: The U6atac snRNP subcomplex is represented in human U4atac/U6atac.U5 tri-snRNPs analyzed biochemically by Schneider, Will, Makarova and colleagues; broader eukaryotic distribution is left for follow-up curation. [DOI:10.1128/MCB.22.10.3219-3229.2002]

Canonical examples

NCBITaxon:9606 Homo sapiens — Human minor-spliceosome U6atac snRNP represented inside U4atac/U6atac.U5 tri-snRNPs in the Schneider, Will and Makarova comparative composition study. [DOI:10.1128/MCB.22.10.3219-3229.2002]

Mechanism graphs

U6atac snRNA and the Lsm2-8 complex are U6atac snRNP constituents (ASSEMBLY)

The U6atac snRNP contains U6atac small nuclear RNA and the GO-grounded Lsm2-8 heptameric ring complex; GO:0005691 also states that additional U6atac-specific proteins are present, with exact family boundaries still to be resolved.

Subject	Predicate	Object	Evidence
U6atac snRNA	contributes constituents to	U6atac snRNP	`GO:0005691` GO:0005691 defines the U6atac snRNP as containing small nuclear RNA U6atac.
Lsm2-8 complex	contributes constituents to	U6atac snRNP	`GO:0005691` GO:0005691 defines the U6atac snRNP as containing the Lsm2-8 heptameric ring complex. `GO:0120115` GO:0120115 is the Gene Ontology cellular-component term for the Lsm2-8 complex.

Discussions

CURATION_TODO (OPEN): Review whether the GO:0120115 Lsm2-8 complex should be split into individual Lsm family components, and resolve exact source-neutral groundings for U6atac-specific protein families that form the U6atac snRNP. The first GO:0005691 record captures U6atac snRNA and the GO-defined Lsm2-8 complex at coarse granularity. GO:0120115 already grounds the Lsm2-8 complex, so follow-up curation should decide whether the Lsm2-8 ring should remain one complex component or be split into individual Lsm-family components and should resolve U6atac-specific protein-family boundaries before splitting that protein inventory.

Evidence

GO:0005691 Gene Ontology cellular-component term for the U6atac snRNP and its exact synonym.
GO:0097525 Gene Ontology cellular-component parent term for spliceosomal snRNP complex.
SO:0000397 Sequence Ontology term for U6atac snRNA.
GO:0120115 Gene Ontology cellular-component term for the Lsm2-8 complex.
DOI:10.1128/MCB.22.10.3219-3229.2002 Schneider, Will, Makarova and colleagues 2002, Human U4/U6.U5 and U4atac/U6atac.U5 tri-snRNPs exhibit similar protein compositions, Molecular and Cellular Biology.
PMID:11971955 PubMed identifier for Schneider, Will, Makarova and colleagues 2002 as reported by NCBI E-utilities.
DOI:10.1515/BC.2005.084 Will and Luehrmann 2005, Splicing of a rare class of introns by the U12-dependent spliceosome, Biological Chemistry.
PMID:16201866 PubMed identifier for Will and Luehrmann 2005 as reported by NCBI E-utilities.

Curation history

2026-09-24T21:04:31Z codex · CREATED_RECORD — Scaffolded by scripts/new_record.py
2026-09-24T21:05:10Z codex · EXPANDED_RECORD — Added the GO exact synonym, spliceosomal snRNP parentage, U6atac snRNA and Lsm2-8 components, human Schneider/Will/Makarova tri-snRNP evidence, a minimal U6atac snRNP constituent graph and a protein-component grounding TODO.
2026-09-24T21:16:33Z codex · ADDRESS_REVIEW — #1525: narrowed the U6atac snRNP protein-component TODO so it frames the already GO:0120115-grounded Lsm2-8 complex as a possible split target rather than an ungrounded component.
2026-09-24T21:17:04Z codex · ADDRESS_REVIEW — #1525: tightened grammar in the Lsm2-8 split rationale.

Source: data/structures/ribonucleoprotein/u6atac_snrnp.yaml