HMGB3: Proteins and Enzymes

High mobility group protein B3 (HMGB3; also HMG-4 and HMG-2a) is a 23 kDa nuclear protein and member of the HMGB family. Human HMGB3 is synthesized as a 200 amino acid (aa) precursor, which is demethylated to produce the 199 aa mature chain. The protein contains two HMG box DNA-binding domains (aa 9-79 and 93-161) and an acidic Asp/Glu-rich region (aa 181-200). Human HMGB3 shares 98% aa sequence identity with mouse and bovine HMGB3. HMGB3 is expressed predominantly in the placenta. It binds preferentially single-stranded DNA and unwinds double stranded DNA.