BoxB is one of the DNA binding domains of HMGB1 protein (HMG boxes). BoxB from HMGB1 is produced in E.coli (Müller et al. Thermodynamics of HMGB1 interaction with duplex DNA. Biochemistry 2001, 40: 10254-61) from an expression plasmid coding for the mammalian sequence, which is totally identical in human and mouse, preceded by four amino acids (MARI) that have been added for the purpose of expression in bacteria (Bianchi et al. The DNA binding site of HMG1 protein is composed of two similar segments (HMG boxes), both of which have counterparts in other eukaryotic regulatory proteins. EMBO J 1992, 11: 1055-63). It has the sequence: