UbcH1, also known as UBE2K, is a member of the ubiquitin E2 conjugating enzyme family, essential components of the ubiquitin cascade.
The selectivity of the ubiquitin cascade for a particular substrate protein relies on the interaction between the E2 conjugating enzyme (of which a cell contains relatively few) and an ubiquitin E3 ligase, of which over 600 have been identified to date. The specific E2-E3 pair required for ubiquitination of a particular substrate protein in vivo may also control the type of ubiquitin modification (mono-, multi-, poly-ubiquitin), the exact substrate lysine residue(s) to be modified and, in the case of polyubiquitination, the chain length and lysine linkage type.
UbcH1 binds directly to the BRCA1 RING motif and is active with BRCA1-BARD1 in in vitro auto-ubiquitination assays. UbcH1 directs the synthesis of K63- or K48-linked ubiquitin chains on BRCA1 and can be utilised in the in vitro synthesis of unanchored K48-linked polyubiquitin chains. Malfunction of the ubiquitin-proteasome system in Alzheimer
