XPA protein is a key factor of the nucleotide excision repair of various DNA lesions including UV-induced photoproducts. It is involved in the damage recognition and the successive assembly of the protein complex for the repair reaction. Patients with the defect in the XPA gene suffer from the extreme sunlight sensitivity leading to erythema and skin cancers. The structure of the central domain of the protein (1XPA) is shown together with the music of the protein sequence.