Ubiquitin-conjugating (UBC), catalytic core domain
IPR000608
Definition
This entry represents the catalytic core domain of E2 ubiquitin-conjugating enzymes and similar sequences mainly found in eukaryotes. It is an α/β domain. Ubiquitin-conjugating enzymes (UBC or E2 enzymes) ([ec:2.3.2.23]) [[cite:PMID:2193438], [cite:PMID:1647207], [cite:PMID:1656558]] catalyse the covalent attachment of ubiquitin to target proteins. Ubiquitinylation is an ATP-dependent process that involves the action of at least three enzymes: a ubiquitin-activating enzyme (E1, [interpro:IPR000011]), a ubiquitin-conjugating enzyme (E2), and a ubiquitin ligase (E3, [interpro:IPR000569], [interpro:IPR003613]), which work sequentially in a cascade PMID:14998368. The E1 enzyme mediates an ATP-dependent transfer of a thioester-linked ubiquitin molecule to a cysteine residue on the E2 enzyme. The E2 enzyme then either transfers the ubiquitin moiety directly to a substrate, or to an E3 ligase, which can also ubiquitinylate a substrate. There are several different E2 enzymes (over 30 in humans), which are broadly grouped into four classes, all of which have a core catalytic domain (containing the active site cysteine), and some of which have short N- and C-terminal amino acid extensions: class I enzymes consist of just the catalytic core domain (UBC), class II possess a UBC and a C-terminal extension, class III possess a UBC and an N-terminal extension, and class IV possess a UBC and both N- and C-terminal extensions. These extensions appear to be important for some subfamily function, including E2 localisation and protein-protein interactions PMID:15545318. In addition, there are proteins with an E2-like fold that are devoid of catalytic activity (such as protein crossbronx from flies), but which appear to assist in poly-ubiquitin chain formation.
40 human proteins with this domain
Each is a reviewed human protein in the Seroatlas serome and a potential autoantibody target; this domain groups them into one antibody-relevant category. Every entry links to its own record.
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