InterPro domain: IPR015940

UBA domains are a commonly occurring sequence motif of approximately 45 amino acid residues that are found in diverse proteins involved in the ubiquitin/proteasome pathway, DNA excision-repair, and cell signalling via protein kinases [ 1 ]. The human homologue of yeast Rad23A is one example of a nucleotide excision-repair protein that contains both an internal and a C-terminal UBA domain. The solution structure of human Rad23A UBA(2) showed that the domain forms a compact three-helix bundle [ 2 ]. Comparison of the structures of UBA(1) and UBA(2) reveals that both form very similar folds and have a conserved large hydrophobic surface patch which may be a common protein-interacting surface present in diverse UBA domains. Evidence that ubiquitin binds to UBA domains leads to the prediction that the hydrophobic surface patch of UBA domains interacts with the hydrophobic surface on the five-stranded beta-sheet of ubiquitin [ 3 ].

This domain is similar in sequence to the N-terminal domain of translation elongation factor EF1B (or EF-Ts) from bacteria, mitochondria and chloroplasts [ 4 ].

1. The UBA domain: a sequence motif present in multiple enzyme classes of the ubiquitination pathway. Trends Biochem. Sci. 21, 172-3
2. Structure of a human DNA repair protein UBA domain that interacts with HIV-1 Vpr. Nat. Struct. Biol. 5, 1042-7
3. Solution structures of UBA domains reveal a conserved hydrophobic surface for protein-protein interactions. J. Mol. Biol. 319, 1243-55
4. The structure of the Escherichia coli EF-Tu.EF-Ts complex at 2.5 A resolution. Nature 379, 511-8