UBE2M UniProt P61081

1 alternative isoform · canonical 183 aa · nucleus; cytosol

UBE2M (hUbc12/UBC12) is the primary E2 NEDD8-conjugating enzyme that drives neddylation of cullin-RING E3 ligases, coupling protein modification to cell-cycle, DNA-repair, immune, and metabolic programs [PMID:10828074, PMID:25025768]. It is charged with activated NEDD8 by the NEDD8 E1 (APPBP1-UBA3), which recruits UBE2M through a ubiquitin-like binding domain that engages the E2 catalytic core in a manner overlapping the E3-binding surface, and transfer to substrates requires the essential active-site cysteine C111 [PMID:15694336, PMID:10828074]. Substrate specificity is sharpened by the co-E3 DCN1, which binds a 12-residue N-terminal UBE2M peptide; this interaction is selectively required for neddylation of cullin 3 (and cullin 1), and disrupting it with peptidomimetic or small-molecule inhibitors converts these cullins to inactive un-neddylated forms [PMID:29074978, PMID:29438612, PMID:42067003]. Through cullin neddylation UBE2M activates CRLs that turn over key substrates including CDT1, p21, p27, Wee1, and Claspin, so its loss stabilizes these factors, blocks cell-cycle progression, impairs RAD51-dependent homologous recombination, and elevates DNA damage [PMID:25025768, PMID:31208947]. Beyond cullins, UBE2M directly neddylates a growing set of non-cullin substrates — TRIM21, MKK7, EGFR, VEGFR2, NAA10, and USP39 — typically stabilizing them by antagonizing their ubiquitin-mediated degradation, thereby tuning inflammatory, MAPK/JNK, receptor-tyrosine-kinase, and translation pathways [PMID:37343564, PMID:41361309, PMID:41857595, PMID:42209461, PMID:41680469, PMID:42111190]. UBE2M can also act as a ubiquitylation E2: under stress it partners with Parkin-DJ-1 to degrade the sister neddylation E2 UBE2F, inactivating CRL5 [PMID:29932898]. Its own activity and abundance are controlled by PRMT1-mediated arginine methylation at R169, by TRIM21-mediated ubiquitination in a STAT1/IFN-I negative-feedback loop, and by a primate-specific PINK1 interaction that sustains UBE2M protein levels [PMID:36662617, PMID:41298302, PMID:40744915].