Multifunctional protein with various roles in different cellular compartments. May act in a redox sensitive manner (By similarity). Associates with chromatin and binds DNA with a preference to non-canonical DNA structures such as single-stranded DNA (PubMed:14672558). Can bent DNA and enhance DNA flexibility by looping thus providing a mechanism to promote activities on various gene promoters. Proposed to be involved in the innate immune response to nucleic acids by acting as a cytoplasmic promiscuous immunogenic DNA/RNA sensor. Involved in inflammatory response to antigenic stimulus coupled with pro-inflammatory activity (By similarity). Reduction/oxidation of cysteine residues Cys-23, Cys-45 and Cys-106 and a possible intramolecular disulfide bond involving Cys-23 and Cys-45 give rise to different redox forms with specific functional activities in various cellular compartments: 1- fully reduced HMGB2 (HMGB2C23hC45hC106h), 2- disulfide HMGB2 (HMGB2C23-C45C106h) and 3- sulfonyl HMGB2 (HMGB2C23soC45soC106so). Belongs to the HMGB family.