MAGOH, the human homolog of Drosophila mago nashi, is required for embryo development. MAGOH is ubiquitously expressed in adult tissues. It has an unusual structure consiting of an extremely flat, six-stranded anti-parallel β sheet packed next to two helices. MAGOH interacts with the Y14 protein to form a complex that plays a crucial role in postsplicing processing (including nuclear export and cytoplasmic localization of the mRNA) and in the nonsense-mediated mRNA decay (NMD) surveillance p