Ubiquitin-conjugating enzyme E2 K (UBE2K)

Accepts ubiquitin in the E1 complex and catalyzes its covalent attachment to other proteins. In vitro, in the presence or in the absence of BRCA1-BARD1 E3 ubiquitin-protein ligase complex, catalyzes the synthesis of 'Lys-48'-linked polyubiquitin chains.

Does not transfer ubiquitin directly to but elongates monoubiquitinated substrate protein. Mediates the selective degradation of short-lived and abnormal proteins, like the endoplasmic reticulum-associated degradation (ERAD) of misfolded lumenal proteins.