Essential factor involved in transcription-coupled nucleotide excision repair (TCR) which allows RNA polymerase II-blocking lesions to be rapidly removed from the transcribed strand of active genes. Upon DNA-binding, it locally modifies DNA conformation by wrapping the DNA around itself, thereby modifying the interface between stalled RNA polymerase II and DNA. It is required for transcription-coupled repair complex formation. Homodimer. Binds DNA. Expressed in proliferating tissues. Highly expressed in shoot apical meristem (SAM). Expressed in roots, young leaves, flag leaves, and panicles. Expressed at very low levels in mature leaves. Induced by gamma irradiation. Belongs to the SNF2/RAD54 helicase family.