SAGA complex

GO:0000124 · Other · Multiprotein complex · Proposed

A SAGA-type histone acetyltransferase complex that deubiquitinates H2A and/or H2B. This complex is organized into several functional submodules: a structural core including the activator binding module and consisting of ADA1 or a homolog, members of the SPT and TAF protein families as well as promotor recruitment factor TRRAP/TRA1, a histone acetyltransferase (HAT) module consisting of GCN5/KAT2A or PCAF/KAT2B, ADA2, ADA3/NGG1, and SGF29 or homologues thereof, a histone deubiquitinase (DUB) module consisting of ATXN7/SGF73, ATXN7L3/SGF11, ENY2/SUS1 and USP22/UBP8 or homologues thereof, and in some taxa a splicing module consisting of SF3B3 and SF3B5 or homologues thereof (not in fungi). In budding yeast also contains Spt8 which distinguishes it from SAGA-like (SLIK) complex (GO:0046695). [GO:0000124]

Synonyms: Spt-Ada-Gcn5-acetyltransferase complex

Has part: DUBm complex (GO:0071819)

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

Components

Component	Type	Part of / acts on	Grounding	Genes	Essential	Role
Tra1 SAGA subunit	Protein	part of	Reviewed label only (reviewed name; no accession asserted)	TRA1	UNKNOWN	Activator-binding module constituent of the budding-yeast SAGA coactivator complex. `DOI:10.1038/s41586-020-1933-5` Wang et al. 2020 purified endogenous Saccharomyces cerevisiae SAGA, reported all 19 subunits, and resolved the Tra1, core, HAT and DUB module architecture.
Taf5 SAGA core subunit	Protein	part of	Reviewed label only (reviewed name; no accession asserted)	TAF5	UNKNOWN	WD40-propeller core-module constituent that links the octamer-like fold to the SAGA core. `DOI:10.1038/s41586-020-1933-5` Wang et al. 2020 purified endogenous Saccharomyces cerevisiae SAGA, reported all 19 subunits, and resolved the Tra1, core, HAT and DUB module architecture.
Taf6 SAGA core subunit	Protein	part of	Reviewed label only (reviewed name; no accession asserted)	TAF6	UNKNOWN	Core-module constituent of the Taf6-Taf9 histone-fold pair in budding-yeast SAGA. `DOI:10.1038/s41586-020-1933-5` Wang et al. 2020 purified endogenous Saccharomyces cerevisiae SAGA, reported all 19 subunits, and resolved the Tra1, core, HAT and DUB module architecture.
Taf9 SAGA core subunit	Protein	part of	Reviewed label only (reviewed name; no accession asserted)	TAF9	UNKNOWN	Core-module constituent of the Taf6-Taf9 histone-fold pair in budding-yeast SAGA. `DOI:10.1038/s41586-020-1933-5` Wang et al. 2020 purified endogenous Saccharomyces cerevisiae SAGA, reported all 19 subunits, and resolved the Tra1, core, HAT and DUB module architecture.
Taf10 SAGA core subunit	Protein	part of	Reviewed label only (reviewed name; no accession asserted)	TAF10	UNKNOWN	Core-module constituent of the Taf10-Spt7 histone-fold pair in budding-yeast SAGA. `DOI:10.1038/s41586-020-1933-5` Wang et al. 2020 purified endogenous Saccharomyces cerevisiae SAGA, reported all 19 subunits, and resolved the Tra1, core, HAT and DUB module architecture.
Taf12 SAGA core subunit	Protein	part of	Reviewed label only (reviewed name; no accession asserted)	TAF12	UNKNOWN	Core-module constituent of the Taf12-Ada1 histone-fold pair that also tethers the Tra1 module. `DOI:10.1038/s41586-020-1933-5` Wang et al. 2020 purified endogenous Saccharomyces cerevisiae SAGA, reported all 19 subunits, and resolved the Tra1, core, HAT and DUB module architecture.
Spt3 SAGA core subunit	Protein	part of	Reviewed label only (reviewed name; no accession asserted)	SPT3	UNKNOWN	TBP-interacting core-module constituent that contributes two histone-fold domains. `DOI:10.1038/s41586-020-1933-5` Wang et al. 2020 purified endogenous Saccharomyces cerevisiae SAGA, reported all 19 subunits, and resolved the Tra1, core, HAT and DUB module architecture.
Spt7 SAGA core subunit	Protein	part of	Reviewed label only (reviewed name; no accession asserted)	SPT7	UNKNOWN	Core-module constituent of the Taf10-Spt7 histone-fold pair in budding-yeast SAGA. `DOI:10.1038/s41586-020-1933-5` Wang et al. 2020 purified endogenous Saccharomyces cerevisiae SAGA, reported all 19 subunits, and resolved the Tra1, core, HAT and DUB module architecture.
Spt20 SAGA core subunit	Protein	part of	Reviewed label only (reviewed name; no accession asserted)	SPT20	UNKNOWN	Core-module constituent that stabilizes the Taf5-Taf6 submodule and tethers Tra1. `DOI:10.1038/s41586-020-1933-5` Wang et al. 2020 purified endogenous Saccharomyces cerevisiae SAGA, reported all 19 subunits, and resolved the Tra1, core, HAT and DUB module architecture.
Ada1 SAGA core subunit	Protein	part of	Reviewed label only (reviewed name; no accession asserted)	ADA1	UNKNOWN	Core-module constituent of the Taf12-Ada1 histone-fold pair in budding-yeast SAGA. `DOI:10.1038/s41586-020-1933-5` Wang et al. 2020 purified endogenous Saccharomyces cerevisiae SAGA, reported all 19 subunits, and resolved the Tra1, core, HAT and DUB module architecture.
Spt8 SAGA TBP-interacting subunit	Protein	part of	Reviewed label only (reviewed name; no accession asserted)	SPT8	UNKNOWN	TBP-interacting budding-yeast SAGA constituent flexibly connected to the core module. `DOI:10.1038/s41586-020-1933-5` Wang et al. 2020 purified endogenous Saccharomyces cerevisiae SAGA, reported all 19 subunits, and resolved the Tra1, core, HAT and DUB module architecture.
Gcn5 SAGA HAT subunit	Protein	part of	Reviewed label only (reviewed name; no accession asserted)	GCN5	UNKNOWN	Catalytic histone acetyltransferase constituent of the SAGA HAT module. `DOI:10.1038/s41586-020-1933-5` Wang et al. 2020 purified endogenous Saccharomyces cerevisiae SAGA, reported all 19 subunits, and resolved the Tra1, core, HAT and DUB module architecture.
Ada2 SAGA HAT subunit	Protein	part of	Reviewed label only (reviewed name; no accession asserted)	ADA2	UNKNOWN	Adaptor constituent of the SAGA histone acetyltransferase module. `DOI:10.1038/s41586-020-1933-5` Wang et al. 2020 purified endogenous Saccharomyces cerevisiae SAGA, reported all 19 subunits, and resolved the Tra1, core, HAT and DUB module architecture.
Ada3 SAGA HAT subunit	Protein	part of	Reviewed label only (reviewed name; no accession asserted)	ADA3	UNKNOWN	Adaptor constituent of the SAGA histone acetyltransferase module. `DOI:10.1038/s41586-020-1933-5` Wang et al. 2020 purified endogenous Saccharomyces cerevisiae SAGA, reported all 19 subunits, and resolved the Tra1, core, HAT and DUB module architecture.
Sgf29 SAGA HAT subunit	Protein	part of	Reviewed label only (reviewed name; no accession asserted)	SGF29	UNKNOWN	SGF-family constituent of the SAGA histone acetyltransferase module. `DOI:10.1038/s41586-020-1933-5` Wang et al. 2020 purified endogenous Saccharomyces cerevisiae SAGA, reported all 19 subunits, and resolved the Tra1, core, HAT and DUB module architecture.
Ubp8 SAGA DUB subunit	Protein	part of	Reviewed label only (reviewed name; no accession asserted)	UBP8	UNKNOWN	Catalytic histone H2B deubiquitinase constituent of the SAGA DUB module. `DOI:10.1038/s41586-020-1933-5` Wang et al. 2020 purified endogenous Saccharomyces cerevisiae SAGA, reported all 19 subunits, and resolved the Tra1, core, HAT and DUB module architecture.
Sgf11 SAGA DUB subunit	Protein	part of	Reviewed label only (reviewed name; no accession asserted)	SGF11	UNKNOWN	SGF-family constituent of the SAGA deubiquitinating module. `DOI:10.1038/s41586-020-1933-5` Wang et al. 2020 purified endogenous Saccharomyces cerevisiae SAGA, reported all 19 subunits, and resolved the Tra1, core, HAT and DUB module architecture.
Sus1 SAGA DUB subunit	Protein	part of	Reviewed label only (reviewed name; no accession asserted)	SUS1	UNKNOWN	ENY2/Sus1-family constituent of the SAGA deubiquitinating module. `DOI:10.1038/s41586-020-1933-5` Wang et al. 2020 purified endogenous Saccharomyces cerevisiae SAGA, reported all 19 subunits, and resolved the Tra1, core, HAT and DUB module architecture.
Sgf73 SAGA DUB-anchor subunit	Protein	part of	Reviewed label only (reviewed name; no accession asserted)	SGF73	UNKNOWN	SAGA constituent whose N-terminal region belongs to the DUB module and whose central residues anchor DUBm to the core. `DOI:10.1038/s41586-020-1933-5` Wang et al. 2020 purified endogenous Saccharomyces cerevisiae SAGA, reported all 19 subunits, and resolved the Tra1, core, HAT and DUB module architecture.

Taxonomic distribution

NCBITaxon:4932 Saccharomyces cerevisiae — COMMON: Budding yeast is the organism from which Wang et al. 2020 purified endogenous 19-subunit SAGA for cryo-EM structure determination. [DOI:10.1038/s41586-020-1933-5]

Canonical examples

NCBITaxon:4932 Saccharomyces cerevisiae — Wang et al. 2020 purified Saccharomyces cerevisiae SAGA through tagged Spt20 and resolved its Tra1, core, HAT and DUB module organization. [DOI:10.1038/s41586-020-1933-5]

Functions

histone acetyltransferase activity GO:0004402 — The SAGA HAT module contains the Gcn5 catalytic subunit and supports histone acetylation by the complex.
- GO:0004402 GO:0004402 is the Gene Ontology molecular-function term for histone acetyltransferase activity.
- GO:0000124 GO:0000124 defines SAGA as a SAGA-type histone acetyltransferase complex.
- DOI:10.1038/s41586-020-1933-5 Wang et al. 2020 describe the SAGA HAT module as containing the histone H3 acetyltransferase Gcn5.
cysteine-type deubiquitinase activity GO:0004843 — The SAGA DUB module deubiquitinates histone H2B through the Ubp8 catalytic subunit.
- GO:0004843 GO:0004843 is the Gene Ontology molecular-function term for cysteine-type deubiquitinase activity.
- GO:0000124 GO:0000124 asserts that the SAGA complex is capable of cysteine-type deubiquitinase activity.
- DOI:10.1101/gad.1144003 Henry et al. 2003 identified SAGA-associated Ubp8 as a mediator of histone H2B deubiquitylation during transcriptional activation.

Mechanism graphs

SAGA supports histone acetylation and deubiquitination (FUNCTION)

In Saccharomyces cerevisiae, the Gcn5-containing HAT module and Ubp8-containing DUB module contribute the histone acetyltransferase and H2B deubiquitinating activities of the SAGA coactivator complex.

Subject	Predicate	Object	Evidence
Gcn5 SAGA HAT subunit	contributes to	SAGA complex	`DOI:10.1038/s41586-020-1933-5` Wang et al. 2020 describe the SAGA HAT module as containing the histone H3 acetyltransferase Gcn5.
Ubp8 SAGA DUB subunit	contributes to	SAGA complex	`GO:0000124` GO:0000124 lists USP22/UBP8 homologues as members of the SAGA DUB module.
SAGA complex	supports	histone acetyltransferase activity	`GO:0000124` GO:0000124 defines SAGA as a SAGA-type histone acetyltransferase complex.
SAGA complex	supports	cysteine-type deubiquitinase activity	`DOI:10.1101/gad.1144003` Henry et al. 2003 identified SAGA-associated Ubp8 as a mediator of histone H2B deubiquitylation.

Discussions

CURATION_TODO (OPEN): Resolve exact source-neutral family groundings for the curated budding-yeast SAGA constituents.

Evidence

GO:0000124 Gene Ontology cellular-component term for SAGA complex and its Spt-Ada-Gcn5-acetyltransferase complex exact synonym.
GO:0070461 Gene Ontology cellular-component parent term for SAGA-type histone acetyltransferase complexes.
GO:0071819 Gene Ontology cellular-component term for the DUBm complex that GO models as a part of SAGA.
GO:0004402 Gene Ontology molecular-function term for histone acetyltransferase activity.
GO:0004843 Gene Ontology molecular-function term for cysteine-type deubiquitinase activity.
PMID:31969703 PubMed identifier for Wang et al. 2020, the budding-yeast SAGA cryo-EM architecture paper.
DOI:10.1038/s41586-020-1933-5 DOI for Wang et al. 2020, 'Structure of the transcription coactivator SAGA', verified through NCBI E-utilities.
PMID:33004486 PubMed identifier for Soffers and Workman 2020, a SAGA chromatin-modifying-complex review cited by GO:0000124.
DOI:10.1101/gad.341156.120 DOI for Soffers and Workman 2020, the SAGA review cited by GO:0000124, verified through NCBI E-utilities.
PMID:14563679 PubMed identifier for Henry et al. 2003, the SAGA-associated Ubp8 histone H2B deubiquitylation paper.
DOI:10.1101/gad.1144003 DOI for Henry et al. 2003, 'Transcriptional activation via sequential histone H2B ubiquitylation and deubiquitylation, mediated by SAGA-associated Ubp8', verified through NCBI E-utilities.

Curation history

2026-09-26T07:19:25Z codex · CREATED_RECORD — Scaffolded by scripts/new_record.py
2026-09-26T07:21:17Z codex · EXPANDED_RECORD — Added SAGA exact synonymy, SAGA-type-complex parentage, DUBm has-part structure, 19 budding-yeast constituent rows, yeast scope, histone acetyltransferase and cysteine-type deubiquitinase activities, GO/PubMed/DOI evidence, a nonmechanistic function graph, and a SAGA subunit-grounding TODO.

Source: data/structures/other/saga_complex.yaml