1LT3:
reference: Crystal structure of heat-labile enterotoxin from Escherichia coli with increased thermostability introduced by an engineered disulfide bond in the A subunit., van den Akker F, Feil IK, Roach C, Platas AA, Merritt EA, Hol WG, Protein Sci 1997 Dec;6(12):2644-9. PMID: 9416616

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