ATP-dependent 3'-5' DNA helicase involved in nucleotide excision repair (NER) of damaged DNA. XPB-R is a paralog of XBP, but is not a component of the TFIIH basal transcription factor and is dispensable for RNA polymerase II transcription. ATP + H2O = ADP + H(+) + phosphate Mutants are much less tolerant than wild-type cells to UV light- and cisplatin-induced DNA damage. Belongs to the helicase family. RAD25/XPB subfamily.