α-Conotoxin AuIB TFA, a potent and selective α3β4 nicotinic acetylcholine receptor (nAChR) antagonist, blocks α3β4 nAChRs expressed in Xenopus oocytes with an IC50 of 0.75 μM.IC50 & Target: IC50: 0.75 μM (α3β4 nAChR; in Xenopus oocytes)In Vitro: α-Conotoxin AuIB blocks the α3β4 receptor with >100-fold higher potency than other receptor subunit combinations, including α2β2, α2β4, α3β2, α4β2, α4β4, and α1β1γδ.