α-conotoxin GID

α-conotoxin GID is a peptide originally isolated from the venom of the Conus geographus. It is composed of 19 amino acids and is folded by two disulphide bonds connecting Cys1-Cys3 and Cys2-Cys4. Based on the number of amino acids between the second and the third cysteine residues (loop I) and the third and fourth cysteine residues (loop II), α-conotoxin GID belongs to the α4/7-conotoxin family. α-conotoxin GID blocks selectively neuronal nicotinic acetylcholine receptors with IC50 values of 3 nM (α3β2 nicotinic receptors), 5 nM (α7) and 150 nM (α4β2). α-conotoxin GID is at least 1000-fold less potent onto the α1β1γδ, α3β4, and α4β4 nicotinic receptors. α-conotoxin GID is a unique α4/7-conotoxin because of its ability to block both α7 and α3β2 isoforms, contrary to conotoxin PnIA or PnIB that are more selective.