This presumed domain is about 120 amino acids in length. It is found associated with CBS domains Pfam:PF00571, as well as the CbiA domain Pfam:PF01656. The function of this domain is unknown. It is named the DRTGG domain after some of the most conserved residues. This domain may be very distantly related to a pair of CBS domains. There are no significant sequence similarities, but its length and association with CBS domains supports this idea (Bateman A, pers. obs.).