UBE2M is a member of the E2 ubiquitin-conjugating enzyme family. Ubiquitination involves at least three classes of enzymes: ubiquitin-activating enzymes; or E1s; ubiquitin-conjugating enzymes; or E2s; and ubiquitin-protein ligases; or E3s. This protein is linked with a ubiquitin-like protein; NEDD8; which can be conjugated to cellular proteins; such as Cdc53/culin. UBE2M accepts the ubiquitin-like protein NEDD8 from the UBA3-NAE1 E1 complex and catalyzes its covalent attachment to other proteins. The specific interaction with the E3 ubiquitin ligase RBX1; but not RBX2; suggests that the RBX1-UBE2M complex neddylates specific target proteins; such as CUL1; CUL2; CUL3 and CUL4. It involved in cell proliferation and is an important cellular mechanism for targeting abnormal or short-lived proteins for degradation.