UBE2B, also known as ubiquitin-conjugating enzyme E2 B, belongs to E2 ubiquitin-conjugating enzyme family. This protein catalyzes the covalent attachment of ubiquitin to other proteins, and associates to the E3 ligase RAD18 to form the UBE2B-RAD18 ubiquitin ligase complex involved in mono-ubiquitination of DNA-associated PCNA on 'Lys-164'. It is required for postreplication repair of UV-damaged DNA. It may be involved in neurite outgrowth. Recombinant human UBE2B protein, fused to His-tag at N-terminus, was expressed in E.coli and purified by using conventional chromatography techniques.