U12-type spliceosomal complex

GO:0005689 · Ribonucleoprotein · Ribonucleoprotein complex · Proposed

Any spliceosomal complex that forms during the splicing of a messenger RNA primary transcript to excise an intron; the series of U12-type spliceosomal complexes is involved in the splicing of the majority of introns that contain atypical AT-AC terminal dinucleotides, as well as other non-canonical introns. The entire splice site signal, not just the terminal dinucleotides, is involved in determining which spliceosome utilizes the site. [GO:0005689]

Synonyms: minor (U12-type) spliceosomal complex; minor spliceosomal complex; AT-AC spliceosomal complex

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
U12-type spliceosomal snRNPs	Protein complex	part of	Reviewed label only (reviewed name; no accession asserted)				State-variable small nuclear ribonucleoprotein constituents of U12-type spliceosomal complexes. `GO:0005689` GO:0005689 is the Gene Ontology cellular-component term for the series of spliceosomal complexes that form during U12-type splicing. `GO:0071015` GO:0071015 defines the U12-type prespliceosome by cooperative binding of heterodimeric U11/U12 snRNP. `GO:0071016` GO:0071016 defines the U12-type precatalytic spliceosome by U4atac/U6atac.U5 tri-snRNP recruitment to the U12-type prespliceosome. `GO:0071017` GO:0071017 defines the U12-type catalytic step 1 spliceosome as the state that retains U12, U5 and U6atac snRNPs after U11 and U4atac snRNP displacement.

Mechanism graphs

U12-type spliceosomal complexes use state-variable snRNPs (ASSEMBLY)

U12-type spliceosomal complexes are the series of minor-spliceosome complexes with snRNP constituents that vary by splicing-cycle state.

Subject	Predicate	Object	Evidence
U12-type spliceosomal snRNPs	contributes state-dependent constituents to	U12-type spliceosomal complex	`GO:0005689` GO:0005689 describes U12-type spliceosomal complexes as the series of spliceosomal complexes that form during U12-type splicing. `GO:0071015` GO:0071015 grounds one child state with U11/U12 snRNP bound to splice signals. `GO:0071017` GO:0071017 grounds one downstream child state that retains U12, U5 and U6atac snRNPs after U11 and U4atac displacement.

Discussions

CURATION_TODO (OPEN): Resolve exact source-neutral snRNP membership for each U12-type spliceosomal state. The first GO:0005689 parent record captures only the state-variable minor-spliceosome snRNP cohort supported by GO. Child records for the U12-type prespliceosome, precatalytic complex, catalytic step 1 and step 2 complexes, post-spliceosomal complex and post-mRNA release complex should carry the exact U11/U12, U4atac/U6atac.U5, U12, U5 and U6atac constituent boundaries that apply to those specific states.

Evidence

GO:0005689 Gene Ontology cellular-component term for U12-type spliceosomal complex and its GO synonyms.
GO:0005681 Gene Ontology cellular-component parent term for spliceosomal complex.
GO:0071015 Gene Ontology cellular-component term for the U12-type prespliceosome child state.
GO:0071016 Gene Ontology cellular-component term for the U12-type precatalytic spliceosome child state.
GO:0071017 Gene Ontology cellular-component term for the U12-type catalytic step 1 spliceosome child state.
GO:0071018 Gene Ontology cellular-component term for the U12-type catalytic step 2 spliceosome child state.
GO:0071022 Gene Ontology cellular-component term for the U12-type post-spliceosomal complex child state.
GO:0071019 Gene Ontology cellular-component term for the U12-type post-mRNA release spliceosomal complex child state.

Curation history

2026-09-25T07:22:36Z codex · CREATED_RECORD — Scaffolded by scripts/new_record.py
2026-09-25T07:23:21Z codex · EXPANDED_RECORD — Added GO exact and narrow synonyms, spliceosomal-complex parentage, a reviewed-label-only state-variable U12-type snRNP cohort, a conservative parent-level snRNP graph and a TODO for exact state-specific U12-type snRNP boundaries.
2026-09-25T07:35:13Z codex · ADDRESS_REVIEW — #1559: widened the state-boundary TODO and record-level evidence to cover all six GO:0005689 child states.

Source: data/structures/ribonucleoprotein/u12_type_spliceosomal_complex.yaml