UFM1 Activating Enzyme/UBA5: ProductsUbiquitin-fold Modifier 1 (UFM1) Activating Enzyme, also known as Ubiquitin-like Modifier Activating Enzyme 5 (UBA5) and Ubiquitin-activating Enzyme E1 Domain-containing Protein 1 (UBE1DC1), is a 404 amino acid (aa) member of the Ubiquitin-activating (E1) enzyme family with a predicted molecular weight of 45 kDa. The mouse and rat UFM1 Activating Enzyme/UBA5 orthologs share 87% and 88% aa sequence identity with the human protein, respectively. UFM1 Activating Enzyme/UBA5 is highly conserved in plants and metazoans but not in yeast. In humans, it is expressed both as the full length protein and as a truncated isoform that lacks aa 1-56. It is widely expressed in human cells where it is localized to the cytoplasm and nucleus. UFM1 Activating Enzyme/UBA5 has a conserved ATP-binding motif in close proximity to an active site cysteine residue, Cys250 in humans, and a metal binding motif, both of which are common to most E1 enzymes. It is the activating enzyme for both UFM1 and SUMO2. UFM1 Activating Enzyme/UBA5 is required for erythroid differentiation in mice.