This family of proteins conserved from plants to humans is a highly specific ubiquitin iso-peptidase that removes ubiquitin from proteins. The modification of cellular proteins by ubiquitin (Ub) is an important event that underlies protein stability and function in eukaryote being a dynamic and reversible process. Otubain carries several key conserved domains: (i) the OTU (ovarian tumour domain) in which there is an active cysteine protease triad (ii) a nuclear localisation signal, (iii) a Ub interaction motif (UIM)-like motif phi-xx-A-xxxs-xx-Ac (where phi indicates an aromatic amino acid, x indicates any amino acid and Ac indicates an acidic amino acid), (iv) a Ub-associated (UBA)-like domain and (v) the LxxLL motif.

1: Otubains: a new family of cysteine proteases in the ubiquitin pathway. Balakirev MY, Tcherniuk SO, Jaquinod M, Chroboczek J; EMBO Rep. 2003;4:517-522. PMID:12704427