Ubiquitin-Conjugating Enzyme E2 G2 (UBE2G2) is an important cellular mechanism for targeting abnormal or short-lived proteins for degradation, which belong to the ubiquitin-conjugating enzyme family. It shares 60% and 100% sequence identity with S.cerevisiae Ubc7 and mouse respectively. The UBE2G2 enzyme and the GP78 E3 ligase are active components of endoplasmic reticulum-associated degradation pathway which is essential for the degradation of misfolded ER proteins. The mechanism of K48-linked poly-ubiquitination by UBE2G2/GP78 appears to involve the transfer of preassembled Ub chains from UBE2G2 to lysine residues in a substrate. The E2 and E3 enzymes form a large hetero-oligomer which brings multiple UBE2G2 molecules into close proximity which allows for Ub transfer between neighboring E2s.