transcription factor TFIIK complex

GO:0070985 · Other · Multiprotein complex · Proposed

A transcription factor complex that forms part of the holo TFIIH complex. In Saccharomyces/human, TFIIK contains Ccl1p/Cyclin H, Tfb3p/MAT1 and Kin28p/CDK7. [GO:0070985]

Synonyms: TFIIK complex; cyclin H-CDK7 complex; Mcs6/Mcs2/Pmh1 complex

Part of: transcription factor TFIIH holo complex (GO:0005675)

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
Ccl1/Cyclin H TFIIK subunit	Protein	part of	Reviewed label only (reviewed name; no accession asserted)	CCL1	UNKNOWN	Cyclin subunit of the TFIIK kinase module. `GO:0070985` GO:0070985 defines TFIIK as containing Ccl1p/Cyclin H in Saccharomyces/human.
Tfb3/MAT1 TFIIK subunit	Protein	part of	Reviewed label only (reviewed name; no accession asserted)	TFB3	UNKNOWN	MAT1-family constituent of the TFIIK kinase module. `GO:0070985` GO:0070985 defines TFIIK as containing Tfb3p/MAT1 in Saccharomyces/human.
Kin28/CDK7 TFIIK subunit	Protein	part of	Reviewed label only (reviewed name; no accession asserted)	KIN28	UNKNOWN	Cyclin-dependent kinase catalytic subunit of the TFIIK kinase module. `GO:0070985` GO:0070985 defines TFIIK as containing Kin28p/CDK7 in Saccharomyces/human.

Taxonomic distribution

NCBITaxon:4932 Saccharomyces cerevisiae — COMMON: GO:0070985 explicitly defines TFIIK with the Saccharomyces Ccl1p, Tfb3p, and Kin28p subunit names. [GO:0070985]

Canonical examples

NCBITaxon:4932 Saccharomyces cerevisiae — GO:0070985 names the budding-yeast TFIIK subunits Ccl1p, Tfb3p, and Kin28p. [GO:0070985]

Mechanism graphs

Ccl1, Tfb3, and Kin28 form TFIIK (ASSEMBLY)

The TFIIK kinase subcomplex of holo TFIIH contains Ccl1p/Cyclin H, Tfb3p/MAT1, and Kin28p/CDK7.

Subject	Predicate	Object	Evidence
Ccl1/Cyclin H TFIIK subunit	contributes to	transcription factor TFIIK complex	`GO:0070985` GO:0070985 names Ccl1p/Cyclin H as a TFIIK subunit.
Tfb3/MAT1 TFIIK subunit	contributes to	transcription factor TFIIK complex	`GO:0070985` GO:0070985 names Tfb3p/MAT1 as a TFIIK subunit.
Kin28/CDK7 TFIIK subunit	contributes to	transcription factor TFIIK complex	`GO:0070985` GO:0070985 names Kin28p/CDK7 as a TFIIK subunit.

Discussions

CURATION_TODO (OPEN): Resolve exact source-neutral family groundings for the curated TFIIK protein constituents. GO:0070985 defines Saccharomyces and human names for three TFIIK complex subunits. Exact cross-eukaryotic InterPro, Pfam, NCBIfam, or UniProt family boundaries for these TFIIK classes need narrower curation before the component labels can be grounded.
INTERPRETATION (RESOLVED): Model TFIIK as the holo-TFIIH kinase subcomplex without merging it into whole holo TFIIH. GO:0070985 denotes the TFIIK complex that forms part of the broader GO:0005675 holo TFIIH complex and defines it as containing the Ccl1p/Cyclin H, Tfb3p/MAT1, and Kin28p/CDK7 protein constituents.

Evidence

GO:0070985 Gene Ontology cellular-component term for the TFIIK subcomplex of the TFIIH holo complex, including exact, related, and narrow synonymy.
GO:0005675 Gene Ontology cellular-component term for the TFIIH holo complex that contains TFIIK.
GO:0090575 OLS reports GO:0090575 RNA polymerase II transcription regulator complex as a GO:0070985 is-a parent.
PMID:19818408 PubMed identifier cited by GO:0070985 for TFIIK.
PMID:22572993 PubMed identifier cited by GO:0070985 for TFIIK.

Curation history

2026-10-01T01:54:33Z codex · CREATED_RECORD — Scaffolded by scripts/new_record.py
2026-10-01T01:56:28Z codex · EXPANDED_RECORD — Added GO synonymy, the direct RNA polymerase II transcription regulator complex parent, holo-TFIIH parthood, three TFIIK protein components, Saccharomyces scope, a nonmechanistic subunit assembly graph, and grounding/boundary discussions.

Source: data/structures/other/transcription_factor_tfiik_complex.yaml