1FTG:
reference: Closure of a tyrosine/tryptophan aromatic gate leads to a compact fold in apo flavodoxin., Genzor CG, Perales-Alcon A, Sancho J, Romero A, Nat Struct Biol 1996 Apr;3(4):329-32. PMID: 8599758

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