Ubiquitin associated domains contain approximately 40 residues and bind ubiquitin non-covalently. They adopt a secondary structure consisting of three alpha-helices, and have been identified in various modular proteins involved in protein trafficking, clathrin assembly/disassembly, DNA repair, proteasomal degradation, and cell cycle regulation [1].

1: Solution structure of the ubiquitin-binding domain in Swa2p from Saccharomyces cerevisiae. Chim N, Gall WE, Xiao J, Harris MP, Graham TR, Krezel AM; Proteins. 2004;54:784-793. PMID:14997574