DNA-binding domains present in proteins of the HMG-box superfamily including the archetypal HMGB proteins, a number of sequence specific transcription factors, and other DNA-binding proteins. The domains consist of 70-80 amino acids that form an L-shaped fold from three alpha-helical segments. The domain has the capacity to recognize and/or induce specific DNA structures and effect the accessibility of the DNA to other proteins involved in transcription, recombination, or DNA repair.