Transcription factor IIH - the protein complex with multiple functions

Transcription factor IIH (TFIIH) is eukaryotic multi protein complex identified in early 90's. Subsequent years have shown exceptional conservation of its structure from yeast to human. Although initially considered to be exclusively a basal transcription factor responsible for initiation of transcription and transition from initiation to elongation, TFIIH is also important in nucleotide excision repair for opening DNA at the site of a lesion and for recruitment of additional repair factors. Recently it was suggested that intact holocomplex of TFIIH is required for cell cycle regulation. Moreover, mutations in TFIIH subunits lead to three distinct genetic disorders: xeroderma pigmentosum (DNA repair disorder/cancer syndrome), Cockayne syndrome (DNA repair disorder/transcription syndrome/segmental progeria) and trichothiodystrophy (DNA repair disorder/transcription syndrome). This review is focused on the TFIIH structure, its role in transcription, DNA repair and cell cycle regulation and association with some human hereditary disorders.