4KH4:
reference: The ATP/ADP Substrate Specificity Switch between Toxoplasma gondii NTPDase1 and NTPDase3 is Caused by an Altered Mode of Binding of the Substrate Base., Krug U, Totzauer R, Zebisch M, Strater N, Chembiochem. 2013 Oct 2. doi: 10.1002/cbic.201300441. PMID: 24115522

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