UbcH1 [UBE2K, E2-25K] (human) (rec.) (His)

UBE2K (UbcH1) is an E2 ubiquitin conjugating enzyme. An E1 activating enzyme is required to attach ubiquitin to UBE2K via an active site cysteine. The mechanism of ubiquitin transfer involves the breaking of a E1-Ub thioester linkage, followed by a reformation of a UBE2K-Ub thioester. UBE2K is capable of synthesizing K48-linked ubiquitin chains and can do so without an E3 ubiquitin ligating enzyme present. UBE2K catalyzes free K48-linked polyubiquitin chains and is known to interact with huntingtin and TRIM6. Although an E3 ligase is not required for chain formation, free UBE2K synthesized K48 polyubiquitin chains have been shown to interact with the E3 TRIM6, leading to activation of IKKepsilon kinase activity and subsequent antiviral activity.