The family includes ubiquitin-conjugating enzyme E2, catalytic (UBCc) domain and ubiquitin (Ub) E2 variant (UEV) domain. They belong to the ubiquitin-conjugating (UBC) superfamily that represents a structural domain with an alpha-beta(4)-alpha(3) core fold. E2 is part of the ubiquitin-mediated protein degradation pathway in which a thioester linkage forms between a conserved cysteine and the C-terminus of ubiquitin, and complexes with ubiquitin protein ligase enzymes, E3. This pathway regulates many fundamental cellular processes. There are also other E2s which form thioester linkages without the use of E3s. Several UBC homologs (TSG101, Mms2, Croc-1 and similar proteins) contains the UEV domain, which lacks the active site cysteine essential for ubiquitination and appear to function in DNA repair pathways.
Feature 1: active site cysteine [active site], 1 residue position
Conserved feature residue pattern:C
Evidence:
Comment:forms a thioester with ubiquitin or ubiquitin-like proteins; others (TSG101, Mms2) lack this cysteine and appear to function in DNA repair pathways
Comment:serves as the point of attachment of ubiquitin prior to transfer to cellular target
Jiyao W et al.(2023). "The conserved domain database in 2023.",