4KBN:
reference: Elucidating Features That Drive the Design of Selective Antifolates Using Crystal Structures of Human Dihydrofolate Reductase., Lamb KM, G-Dayanandan N, Wright DL, Anderson AC, Biochemistry. 2013 Oct 3. PMID: 24053334

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