transcription factor TFIIH core complex

GO:0000439 · Other · Multiprotein complex · Proposed

The 7 subunit core of TFIIH that is a part of either the general transcription factor holo-TFIIH or the nucleotide-excision repair factor 3 complex. In S. cerevisiae/humans the complex is composed of: Ssl2/XPB, Tfb1/p62, Tfb2/p52, Ssl1/p44, Tfb4/p34, Tfb5/p8 and Rad3/XPD. [GO:0000439]

Synonyms: SSL2-core TFIIH complex; core TFIIH complex

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
Ssl2/XPB TFIIH core subunit	Protein	part of	Reviewed label only (reviewed name; no accession asserted)	SSL2	UNKNOWN	Protein constituent of the seven-subunit TFIIH core complex. `GO:0000439` GO:0000439 defines the transcription factor TFIIH core complex as a seven-subunit S. cerevisiae/human complex.
Tfb1/p62 TFIIH core subunit	Protein	part of	Reviewed label only (reviewed name; no accession asserted)	TFB1	UNKNOWN	Protein constituent of the seven-subunit TFIIH core complex. `GO:0000439` GO:0000439 defines the transcription factor TFIIH core complex as a seven-subunit S. cerevisiae/human complex.
Tfb2/p52 TFIIH core subunit	Protein	part of	Reviewed label only (reviewed name; no accession asserted)	TFB2	UNKNOWN	Protein constituent of the seven-subunit TFIIH core complex. `GO:0000439` GO:0000439 defines the transcription factor TFIIH core complex as a seven-subunit S. cerevisiae/human complex.
Ssl1/p44 TFIIH core subunit	Protein	part of	Reviewed label only (reviewed name; no accession asserted)	SSL1	UNKNOWN	Protein constituent of the seven-subunit TFIIH core complex. `GO:0000439` GO:0000439 defines the transcription factor TFIIH core complex as a seven-subunit S. cerevisiae/human complex.
Tfb4/p34 TFIIH core subunit	Protein	part of	Reviewed label only (reviewed name; no accession asserted)	TFB4	UNKNOWN	Protein constituent of the seven-subunit TFIIH core complex. `GO:0000439` GO:0000439 defines the transcription factor TFIIH core complex as a seven-subunit S. cerevisiae/human complex.
Tfb5/p8 TFIIH core subunit	Protein	part of	Reviewed label only (reviewed name; no accession asserted)	TFB5	UNKNOWN	Protein constituent of the seven-subunit TFIIH core complex. `GO:0000439` GO:0000439 defines the transcription factor TFIIH core complex as a seven-subunit S. cerevisiae/human complex.
Rad3/XPD TFIIH core subunit	Protein	part of	Reviewed label only (reviewed name; no accession asserted)	RAD3	UNKNOWN	Protein constituent of the seven-subunit TFIIH core complex. `GO:0000439` GO:0000439 defines the transcription factor TFIIH core complex as a seven-subunit S. cerevisiae/human complex.

Taxonomic distribution

NCBITaxon:4932 Saccharomyces cerevisiae — COMMON: GO:0000439 defines the TFIIH core complex as a seven-subunit S. cerevisiae/human complex. [GO:0000439]

Canonical examples

NCBITaxon:4932 Saccharomyces cerevisiae — The Gene Ontology TFIIH core definition enumerates budding-yeast Ssl2, Tfb1, Tfb2, Ssl1, Tfb4, Tfb5, and Rad3 as the seven core constituents. [GO:0000439]

Mechanism graphs

Seven TFIIH core subunits form the TFIIH core complex (ASSEMBLY)

The Ssl2/XPB, Tfb1/p62, Tfb2/p52, Ssl1/p44, Tfb4/p34, Tfb5/p8, and Rad3/XPD subunit classes constitute the TFIIH core complex.

Subject	Predicate	Object	Evidence
Ssl2/XPB TFIIH core subunit	contributes to	transcription factor TFIIH core complex	`GO:0000439` GO:0000439 defines the seven S. cerevisiae/human TFIIH core complex constituents.
Tfb1/p62 TFIIH core subunit	contributes to	transcription factor TFIIH core complex	`GO:0000439` GO:0000439 defines the seven S. cerevisiae/human TFIIH core complex constituents.
Tfb2/p52 TFIIH core subunit	contributes to	transcription factor TFIIH core complex	`GO:0000439` GO:0000439 defines the seven S. cerevisiae/human TFIIH core complex constituents.
Ssl1/p44 TFIIH core subunit	contributes to	transcription factor TFIIH core complex	`GO:0000439` GO:0000439 defines the seven S. cerevisiae/human TFIIH core complex constituents.
Tfb4/p34 TFIIH core subunit	contributes to	transcription factor TFIIH core complex	`GO:0000439` GO:0000439 defines the seven S. cerevisiae/human TFIIH core complex constituents.
Tfb5/p8 TFIIH core subunit	contributes to	transcription factor TFIIH core complex	`GO:0000439` GO:0000439 defines the seven S. cerevisiae/human TFIIH core complex constituents.
Rad3/XPD TFIIH core subunit	contributes to	transcription factor TFIIH core complex	`GO:0000439` GO:0000439 defines the seven S. cerevisiae/human TFIIH core complex constituents.

Discussions

CURATION_TODO (OPEN): Resolve exact source-neutral family groundings for the curated TFIIH core protein constituents. GO:0000439 defines S. cerevisiae and human names for seven TFIIH core complex subunits. Exact cross-eukaryotic InterPro, Pfam, NCBIfam or UniProt family boundaries for these TFIIH core classes need narrower curation before the component labels can be grounded.
INTERPRETATION (RESOLVED): Keep generic GO:0000439 separate from its context-specific holo-TFIIH and NEF3 portion terms. GO:0000439 denotes the reusable seven-subunit TFIIH core. GO:0000438 and GO:0000440 denote that core only when it is part of the general transcription factor TFIIH or the NEF3 complex, respectively.

Evidence

GO:0000439 Gene Ontology cellular-component term for the seven-subunit transcription factor TFIIH core complex and its SSL2-core and core-TFIIH exact synonyms.
GO:0090575 OLS reports GO:0090575 RNA polymerase II transcription regulator complex as the GO:0000439 is-a parent.

Curation history

2026-09-30T23:47:58Z codex · CREATED_RECORD — Scaffolded by scripts/new_record.py
2026-09-30T23:49:03Z codex · EXPANDED_RECORD — Added GO synonymy, RNA polymerase II transcription regulator complex parentage, seven reviewed-label-only TFIIH core constituents, Saccharomyces scope, a nonmechanistic assembly graph, and TFIIH-core grounding and portion-boundary discussions.

Source: data/structures/other/transcription_factor_tfiih_core_complex.yaml