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BTAF1

TATA-binding protein-associated factor 172 · UniProt O14981

Length
1849 aa
Mass
206.9 kDa
Annotated
2026-06-09
9 papers in source corpus 8 papers cited in narrative 8 extracted findings
Cross-family judge vs UniProt: Affinage preferred faithfulness: 6/6 claims corpus-supported (100%)

Mechanistic narrative

Synthesis pass · prose summary of the discoveries below

BTAF1 (TAFII170/TAF-172) is an ATP-dependent regulator of TBP that governs RNA polymerase II transcription by controlling the availability of TBP on promoter DNA (PMID:1387711, PMID:14557059). It is the 170 kDa TAF subunit of the two-subunit B-TFIID complex, which it forms with TBP and which carries intrinsic (d)ATPase activity (PMID:1387711, PMID:9342322); recombinant BTAF1 reconstitutes this enzymatic activity and is the orthologue of yeast MOT1 and Drosophila moira, marking it as a global transcriptional regulator (PMID:8083216, PMID:9342322). BTAF1 engages TBP through three amino-terminal HEAT-repeat regions that target the concave DNA-binding surface of TBP, and one of these regions (residues 290–381) competitively inhibits TBP–TATA box complex formation, providing the structural basis for reversible occupancy of TBP's DNA-binding face (PMID:11585931). Using ATP hydrolysis, BTAF1 dissociates TBP from TATA DNA, dynamically redistributing TBP on promoters and thereby acting as both a repressor and a positive regulator of pol II transcription (PMID:14557059). This activity is modulated by NC2alpha (DRAP1), which physically interacts with BTAF1 and stimulates its ATP-dependent association with TBP independently of BTAF1 ATPase activity, whereas NC2beta does not bind and instead interferes with the BTAF1–TBP interaction (PMID:15509807). Single-particle electron microscopy resolved the B-TFIID architecture, placing the BTAF1 C-terminus in the large 170 kDa domain and the BTAF1 N-terminus together with TBP at the tip of a protruding thumb (PMID:14988402).

Mechanistic history

Synthesis pass · year-by-year structured walk · 7 steps
  1. 1992 High

    Established that a distinct TBP-containing complex, B-TFIID, exists as a two-subunit assembly with enzymatic activity, defining BTAF1 as a novel 170 kDa TAF rather than part of canonical TFIID.

    Evidence Biochemical purification of B-TFIID from mammalian extracts with subunit composition and ATPase assays

    PMID:1387711

    Open questions at the time
    • Did not assign the ATPase activity to a specific subunit
    • No sequence or domain identity for the 170 kDa TAF
  2. 1994 High

    Identified the yeast counterpart as MOT1-encoded Taf170 forming a binary TBP complex separate from TFIID, anchoring BTAF1 in a conserved regulatory framework.

    Evidence Protein sequencing, co-fractionation, and complex resolution in yeast

    PMID:8083216

    Open questions at the time
    • Mechanism by which the binary complex regulates transcription not resolved here
    • Human orthologue not yet cloned
  3. 2000 Medium

    Characterized the human BTAF1 gene structure and minimal promoter, providing genomic context for the transcript.

    Evidence Genomic cloning, ribonuclease-protection, promoter deletion analysis, and chromosomal mapping

    PMID:10642510

    Open questions at the time
    • No functional consequence of promoter elements on BTAF1 expression in vivo
    • Regulatory inputs to the TATA-less promoter unknown
  4. 1997 High

    Cloned human BTAF1 and demonstrated that the recombinant protein itself carries the (d)ATPase activity and is the TAF subunit of B-TFIID, with homology marking it as a global pol II regulator.

    Evidence cDNA cloning, recombinant expression, ATPase assays, co-fractionation and co-precipitation

    PMID:9342322

    Open questions at the time
    • Substrate or function of the ATPase activity not yet defined
    • No domain mapping of the TBP interaction
  5. 2001 High

    Mapped the TBP-binding determinants to three N-terminal HEAT-repeat regions targeting TBP's concave DNA-binding surface, explaining how BTAF1 competes with TATA-box binding.

    Evidence Deletion mutagenesis, altered-specificity TBP mutant binding, and competitive TBP-DNA binding assays

    PMID:11585931

    Open questions at the time
    • Did not directly demonstrate ATP-dependent dissociation in this study
    • Contribution of each region to full-length function not quantified
  6. 2004 High

    Resolved the B-TFIID molecular architecture and positioned BTAF1 termini and TBP within the structure, linking domain organization to function.

    Evidence Single-particle electron microscopy with immunolabeling of native and recombinant complexes

    PMID:14988402

    Open questions at the time
    • No atomic-resolution structure of the BTAF1–TBP interface
    • DNA-bound or ATP-bound conformational states not captured
  7. 2004 Medium

    Defined NC2alpha (DRAP1) as a positive modulator that stimulates BTAF1–TBP association, while NC2beta antagonizes it, adding a regulatory layer to BTAF1 function.

    Evidence Reciprocal co-immunoprecipitation, ATP-dependent binding assays, and ATPase-deficient BTAF1 mutants

    PMID:15509807

    Open questions at the time
    • Functional transcriptional consequence of NC2alpha stimulation not demonstrated on promoters
    • Single-lab data without reciprocal cross-validation in other systems

Open questions

Synthesis pass · forward-looking unresolved questions
  • How BTAF1-mediated TBP redistribution is targeted to specific promoters genome-wide and integrated with other transcription regulators remains unresolved.
  • No genome-wide promoter occupancy mapping in the corpus
  • Physiological gene targets of BTAF1 regulation not defined
  • No atomic structure of the ATP-driven TBP dissociation reaction

Mechanism profile

Synthesis pass · controlled-vocabulary classification · explore literature graph →
Molecular activity
GO:0016787 hydrolase activity 3 GO:0098772 molecular function regulator activity 2 GO:0140110 transcription regulator activity 2 GO:0140657 ATP-dependent activity 2
Localization
GO:0005634 nucleus 2
Pathway
R-HSA-74160 Gene expression (Transcription) 2
Partners
DRAP1TBP
Complex memberships
B-TFIID

Evidence

Reading pass · 8 per-paper findings extracted from the source corpus
Year Finding Method Journal Conf PMIDs
1992 B-TFIID, purified from mammalian cell extracts, consists of two subunits: TBP and a 170 kDa TAF (BTAF1/TAFII170); the highly purified B-TFIID fractions possess (d)ATPase activity. Biochemical purification, subunit composition analysis, ATPase activity assay Proceedings of the National Academy of Sciences of the United States of America High 1387711
1994 Yeast TAFII170 (Taf170) is encoded by MOT1 and forms a distinct TBP-Taf170 binary complex separate from the multisubunit TFIID complex, establishing it as a bona fide TAF with a unique role in transcriptional regulation. Protein sequencing of purified TAF, co-fractionation, complex resolution by biochemical methods The Journal of biological chemistry High 8083216
1997 Recombinant human TAFII170 (BTAF1) has (d)ATPase activity, and co-fractionation/co-precipitation experiments confirmed it is the TAF subunit of B-TFIID. Its primary structure shows homology to yeast MOT1 and Drosophila moira, consistent with a role as a global regulator of pol II transcription. cDNA cloning, recombinant protein expression, ATPase assay, co-fractionation, co-precipitation Proceedings of the National Academy of Sciences of the United States of America High 9342322
2001 BTAF1 (TAFII170) interacts with TBP via three amino-terminal regions (residues 2–137, 290–381, and 380–460), each containing HEAT repeats; the interaction targets the concave DNA-binding surface of TBP, and region 290–381 inhibits TBP–TATA box complex formation, supporting a mechanism by which BTAF1 induces high-mobility TBP–DNA binding through reversible competition for TBP's concave surface. Deletion mutagenesis, binding assays with altered-specificity TBP mutant (TBPAS), competitive inhibition assays with TAFII230, TBP-DNA binding assays Molecular and cellular biology High 11585931
2003 BTAF1 (and its yeast ortholog Mot1p) can dissociate TBP from TATA DNA complexes in an ATP hydrolysis-dependent manner, functioning both as a repressor and positive regulator of pol II transcription by dynamically redistributing TBP on promoters. Review synthesizing genetic and biochemical experiments (ATP-dependent TBP dissociation assays, genetic repressor/activator analyses) Gene Medium 14557059
2004 NC2alpha (DRAP1) physically interacts with BTAF1 and stimulates BTAF1's ATP-dependent association with TBP; NC2beta does not associate with BTAF1 and interferes with the BTAF1–TBP interaction. The stimulatory effect of NC2alpha does not require BTAF1's ATPase activity or phosphorylation of NC2alpha. Co-immunoprecipitation, cell extract binding assays with ATP, ATPase-deficient BTAF1 mutants, domain-specific interaction experiments Molecular and cellular biology Medium 15509807
2004 Electron microscopy single-particle analysis of native and recombinant B-TFIID determined its molecular architecture at 28 Å resolution: a 15×9 nm structure with a large ~170 kDa domain subdivided into two subdomains and a protruding thumb. Immunolabeling localized the C-terminus of BTAF1 in the 170-kDa domain, the N-terminus and TBP at the end of the thumb, and the central portion of BTAF1 at the base of the thumb. Electron microscopy, single-particle image analysis, immunolabeling with antibodies against BTAF1 termini and TBP The Journal of biological chemistry High 14988402
2000 The human BTAF1 (TAFII170) gene contains 37 introns, lacks a canonical TATA box and initiator element at its promoter, maps to chromosome 10q22-q23, and a 264 bp promoter fragment is sufficient to direct transcription as shown by deletion analysis. Genomic cloning, ribonuclease-protection assays, promoter deletion analysis, chromosomal mapping by two independent methods The Biochemical journal Medium 10642510

Source papers

Stage 0 corpus · 9 papers · ranked by NIH iCite citations
Year Title Journal Citations PMID
1994 Yeast Taf170 is encoded by MOT1 and exists in a TATA box-binding protein (TBP)-TBP-associated factor complex distinct from transcription factor IID. The Journal of biological chemistry 78 8083216
1992 Composition of transcription factor B-TFIID. Proceedings of the National Academy of Sciences of the United States of America 77 1387711
2003 Roles for BTAF1 and Mot1p in dynamics of TATA-binding protein and regulation of RNA polymerase II transcription. Gene 46 14557059
1997 Cloning of the cDNA for the TATA-binding protein-associated factorII170 subunit of transcription factor B-TFIID reveals homology to global transcription regulators in yeast and Drosophila. Proceedings of the National Academy of Sciences of the United States of America 41 9342322
2001 TAF(II)170 interacts with the concave surface of TATA-binding protein to inhibit its DNA binding activity. Molecular and cellular biology 30 11585931
2004 NC2alpha interacts with BTAF1 and stimulates its ATP-dependent association with TATA-binding protein. Molecular and cellular biology 25 15509807
2003 Polyhomeotic stably associates with molecular chaperones Hsc4 and Droj2 in Drosophila Kc1 cells. Developmental biology 16 14550797
2004 Molecular architecture of the basal transcription factor B-TFIID. The Journal of biological chemistry 10 14988402
2000 The gene for human TATA-binding-protein-associated factor (TAFII) 170: structure, promoter and chromosomal localization. The Biochemical journal 5 10642510

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