α-Conotoxin ImI is a conotoxin that has been found in C. imperialis and has receptor antagonist and anticancer activities.1 It is a peptide antagonist of homomeric α7 nicotinic acetylcholine receptors (nAChRs; IC50 = 220 nM). α-Conotoxin ImI is selective for α7 nAChRs over α2β2, α3β2, α4β2, α2β4, α3β4, α4β4, and α1β1γδ subunit-containing nAChRs at 5 µM but does inhibit homomeric α9 nAChRs (IC50 = 1,800 nM). Administration of paclitaxel in micelles containing α-conotoxin ImI decreases tumor growth in an MCF-7 mouse xenograft model.2 Intracerebroventricular, but not intraperitoneal, administration of α-conotoxin ImI (20 nmol/animal) induces seizures in rats.3
1.Johnson, D.S., Martinez, J., Elgoyhen, A.B., et al.α-Conotoxin ImI exhibits subtype-specific nicotinic acetylcholine receptor blockade: Preferential inhibition of homomeric α7 and α9 receptorsMol. Pharmacol.48(2)194-199(1995) 2.Mei, D., Lin, Z., Fu, J., et al.The use of α-conotoxin ImI to actualize the targeted delivery of paclitaxel micelles to α7 nAChR-overexpressing breast cancerBiomaterials4252-65(2015) 3.McIntosh, J.M., Yoshikami, D., Mahe, E., et al.A nicotinic acetylcholine receptor ligand of unique specificity, α-conotoxin ImIJ. Biol. Chem.269(24)16733-16739(1994)