Ubiquitin-related modifier 1

UniProtKB accession:  P40554

Grouped By:  Matching UniProtKB accession

UniProtKB description:  Acts as a sulfur carrier required for 2-thiolation of mcm(5)S(2)U at tRNA wobble positions of cytosolic tRNA(Lys), tRNA(Glu) and tRNA(Gln). Serves as sulfur donor in tRNA 2-thiolation reaction by being thiocarboxylated (-COSH) at its C-terminus by the MOCS3 homolog UBA4. The sulfur is then transferred to tRNA to form 2-thiolation of mcm(5)S(2)U. Prior mcm(5) tRNA modification by the elongator complex is required for 2-thiolation (By similarity) (PubMed:18664566, PubMed:18755837, PubMed:19017811, PubMed:19145231, PubMed:19151091). Also acts as a ubiquitin-like protein (UBL) that is covalently conjugated via an isopeptide bond to lysine residues of target proteins such as AHP1 (PubMed:10713047, PubMed:14551258, PubMed:14555475, PubMed:21209336, PubMed:32004955). Conjugation does not depend on the canonical cascade of E2 ubiquitin-conjugating enzymes and/or E3 ligases. The conjugation reaction requires a thiocarboxylated C-terminus of URM1 and a peroxidatic cysteine in the target protein, as the sulfur atom of the URM1 thiocarboxyl group is transferred to redox-active cysteine residues in the target protein (PubMed:36102610). Oxidative stress specifically induces the formation of UBL-protein conjugates (PubMed:21209336). Covalent modification with URM1 promotes the phase separation of a wide range of proteins into condensates like stress granules (PubMed:38942013). Indirectly involved in regulation of budding and haploid invasive growth (PubMed:14551258).