4HB1:
reference: A designed four helix bundle protein with native-like structure., Schafmeister CE, LaPorte SL, Miercke LJ, Stroud RM, Nat Struct Biol 1997 Dec;4(12):1039-46. PMID: 9406555

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