2G4B:
reference: Structural basis for polypyrimidine tract recognition by the essential pre-mRNA splicing factor U2AF65., Sickmier EA, Frato KE, Shen H, Paranawithana SR, Green MR, Kielkopf CL, Mol Cell. 2006 Jul 7;23(1):49-59. PMID: 16818232

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