3EFX:
reference: Novel binding site identified in a hybrid between cholera toxin and heat-labile enterotoxin: 1.9 A crystal structure reveals the details., Holmner A, Lebens M, Teneberg S, Angstrom J, Okvist M, Krengel U, Structure. 2004 Sep;12(9):1655-67. PMID: 15341730

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