TFIIH is a eukaryotic complex composed of two subcomplexes, the CAK (Cdk activating kinase) and the core-TFIIH. This entry represents Tfb1/GTF2H1, a component of the core-TFIIH basal transcription factor, which consists of seven subunits known as XPB, XPD, GTF2H1 (p62), p52, p44, p34, and p8 in humans and Ssl2, Rad3, Tfb1, Tfb2, Ssl1, Tfb4 and Tfb5 in yeast []. TFIIH is involved in nucleotide excision repair (NER) of DNA and RNA transcription by RNA polymerase II and I [, , ].