This gene encodes an ATP-dependent DNA helicase that functions in nucleotide excision repair. The encoded protein is a subunit of basal transcription factor 2 (TFIIH) and, therefore, also functions in class II transcription. Mutations in this gene are associated with Xeroderma pigmentosum B, Cockayne's syndrome, and trichothiodystrophy. Alternative splicing results in multiple transcript variants.,ERCC3,BTF2,GTF2H,RAD25,TFIIH,TTD2,XPB,Epigenetics & Nuclear Signaling,Transcription Factors,DNA Damage & Repair,Cancer,Cell Biology & Developmental Biology,Apoptosis,Endocrine & Metabolism,Nucleotide metabolism,Purine and pyrimidine synthesis,ERCC3