This is an Ankyrin repeat domain found in TRABID (also known as Ubiquitin thioesterase ZRANB1) (EC:3.4.19.12). In TRABID, the first ankyrin repeat spans residues 260-290 and is connected to the second repeat residues 313-340 by a long linker that packs against what would correspond to the concave surface in an extended ankyrin-repeat structure. Ankyrin-repeat domains mediate protein interactions through a variety of surfaces. The ankyrin domain of TRABID interacts with ubiquitin, hence it is referred to as the ankyrin ubiquitin-binding domain, or AnkUBD [1].

1: An ankyrin-repeat ubiquitin-binding domain determines TRABID's specificity for atypical ubiquitin chains. Licchesi JD, Mieszczanek J, Mevissen TE, Rutherford TJ, Akutsu M, Virdee S, El Oualid F, Chin JW, Ovaa H, Bienz M, Komander D; Nat Struct Mol Biol. 2011;19:62-71. PMID:22157957