1W9H:
reference: Crystal structure of a PIWI protein suggests mechanisms for siRNA recognition and slicer activity., Parker JS, Roe SM, Barford D, EMBO J. 2004 Dec 8;23(24):4727-37. Epub 2004 Nov 25. PMID: 15565169

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