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.
Peptides & proteins
Banerjee J., et al. (2014) Design and synthesis of α-conotoxin GID analogues as selective α4β2 nicotinic acetylcholine receptor antagonists. Biopolymers.; Millard E., et al. (2009) Inhibition of Neuronal Nicotinic Acetylcholine Receptor Subtypes by α-Conotoxin GID and Analogues. JBC.; Nicke A., et al. (2003) Isolation, Structure, and Activity of GID, a Novel 4/7-Conotoxin with an Extended N-terminal Sequence. JBC.
AA sequence: Ile-Arg-Asp-Gla-Cys5-Cys6-Ser-Asn-Pro-Ala-Cys11-Arg-Val-Asn-Asn-Hyp-His-Val-Cys19-OH; Disulfide bonds: Cys5-Cys11 and Cys6-Cys19