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Isolation and characterization of two human transcription factor IIH (TFIIH)-related complexes: ERCC2/CAK and TFIIH.

Transcription factor IIH (TFIIH) is a multisubunit protein complex essential for both the initiation of RNA polymerase class II (pol II)-catalyzed transcription and nucleotide excision repair of DNA. Recent studies have shown that TFIIH copurifies with the cyclin-dependent kinase (cdk)-activating kinase complex (CAK) that includes cdk7, cyclin H, and p36/MAT1. Here we report the isolation of two TFIIH-related complexes: TFIIH* and ERCC2/CAK. TFIIH* consists of a subset of the TFIIH complex proteins including ERCC3 (XPB), p62, p44, p41, and p34 but is devoid of detectable levels of ERCC2 (XPD) and CAK. ERCC2/CAK was isolated as a complex that exhibits CAK activity that cosediments with the three CAK components (cdk7, cyclin H, and p36/MAT1) as well as the ERCC2 (XPD) protein. TFIIH* can support pol II-catalyzed transcription in vitro with lower efficiency compared with TFIIH. This TFIIH*-dependent transcription reaction was stimulated by ERCC2/CAK. The ERCC2/CAK and TFIIH* complexes are each active in DNA repair as shown by their ability to complement extracts prepared from ERCC2 (XPD)- and ERCC3 (XPB)-deficient cells, respectively, in supporting the excision of DNA containing a cholesterol lesion. These data suggest that TFIIH* and ERCC2/CAK interact to form the TFIIH holoenzyme capable of efficiently assembling the pol II transcription initiation complex and directly participating in excision repair reactions.

Pubmed ID: 8692841


  • Reardon JT
  • Ge H
  • Gibbs E
  • Sancar A
  • Hurwitz J
  • Pan ZQ


Proceedings of the National Academy of Sciences of the United States of America

Publication Data

June 25, 1996

Associated Grants

  • Agency: NIGMS NIH HHS, Id: GM32833
  • Agency: NIGMS NIH HHS, Id: GM38559

Mesh Terms

  • Animals
  • CHO Cells
  • Chromatography, Ion Exchange
  • Cricetinae
  • Cyclin-Dependent Kinases
  • DNA Helicases
  • DNA Repair
  • DNA-Binding Proteins
  • Humans
  • Proteins
  • RNA Polymerase II
  • Transcription Factor TFIIH
  • Transcription Factors
  • Transcription Factors, TFII
  • Transcription, Genetic
  • Xeroderma Pigmentosum Group D Protein