1OBP:
reference: Domain swapping creates a third putative combining site in bovine odorant binding protein dimer., Tegoni M, Ramoni R, Bignetti E, Spinelli S, Cambillau C, Nat Struct Biol. 1996 Oct;3(10):863-7. PMID: 8836103

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