This domain is found a variety of proteins involved in biosynthesis of molybdopterin cofactor. The domain is presumed to bind molybdopterin. The structure of this domain is known, and it forms an alpha/beta structure. In the known structure of Gephyrin this domain mediates trimerisation [1].

1: X-ray crystal structure of the trimeric N-terminal domain of gephyrin. Sola M, Kneussel M, Heck IS, Betz H, Weissenhorn W; J Biol Chem 2001;276:25294-25301. PMID:11325967