2IYK:
reference: Crystal structure of the UPF2-interacting domain of nonsense-mediated mRNA decay factor UPF1., Kadlec J, Guilligay D, Ravelli RB, Cusack S, RNA. 2006 Oct;12(10):1817-24. Epub 2006 Aug 24. PMID: 16931876

This OCA Structure page
uses Jmol, developed by the Jmol Development Team (documentation).