α-Conotoxin GID is a paralytic peptide neurotoxin and a selective antagonist of nAChR , with IC 50 s of 5 nM (α7), 3 nM (α3β2), 150 nM (α4β2), respectively. α-Conotoxin GID is small disulfide-rich peptide, with potential to inhibit chronic pain. α-Conotoxin GID contains a C-terminal carboxylate, thus substitution with a C-terminal carboxamide results in loss of α4β2 nAChR. α-Conotoxin GID can be isolated from the Conus species.