[5][6] UBA has been proposed to limit ubiquitin chain elongation and to target polyubiquitinated proteins to the 26S proteasome for degradation.

UBA domains have a common sequence motif of approximately 45 amino acid residues.

[2] 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.

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.