alpha-Conotoxin MI is a 14 amino acid peptidyl toxin isolated from the Conus magus (Magus cone, Magician�s cone snail venom).
It acts on postsynaptic membranes on muscles and blocks mammalian nicotinic ACh channel receptor composed of alpha1/delta subunits with high potency and alpha1/gamma with a low potency.
Structure activity relationship studies were done in order to map the major amino acids in alpha-Conotoxin MI and the overall results show that primarily hydrophobic interactions stabilize the complex between the toxin and the alpha-delta interface of the nAChR. Proline-6 and Tyrosine-12 dramatically reduced toxin potency at the high-affinity alpha-delta site while having comparatively little effect on low-affinity alpha/gamma binding.