Ubiquitin Related Modifier 1 (URM1)

The deduced 101-amino acid protein shares 93% identity with mouse Urm1. knockdown of URM1 via short hairpin RNA reduced the growth rate of HeLa cells. Knockdown of URM1 in human cell lines increased cell size, caused multinucleation, and increased the population of cells with 4n or more chromosomes, suggesting that URM1 is required for cytokinesis and thus for orderly cell cycle progression. Use of a URM1-dependent suicide inhibitor with HEK293 cells showed that URM1 interacted with ATPBD3. Biochemical analysis revealed that the C-terminal thiocarboxylated glycine of URM1 functioned as a sulfur carrier for the thiolation of tRNAs by ATPBD3. Knockdown of either URM1 or ATPBD3 in HeLa cells reduced thiolation of uracil in the anticodon region of tRNA-lys(UUU).