- Alomone Labs α-Conotoxin MI inhibits muscle fetal α1/β1/γ/δ nAChR heterologously expressed in Xenopus oocytes.Time course of α-Conotoxin MI (#STC-370) action on muscle α1/β1/γ/δ nAChR. Current amplitudes were plotted as a function of time. Membrane potential was held at –80 mV and oocytes were stimulated by exposure to 10 μM acetylcholine every 100 seconds. 2 nM (for 3 min) and 20 nM (for 3 min) α-Conotoxin MI were perfused during the period marked by the bar, as indicated.
α-Conotoxin MI is a 14 amino acid peptidyl toxin isolated from the Conus magus (Magus cone, Magician’s cone snail venom)1. It acts on postsynaptic membranes on muscles and blocks mammalian nicotinic ACh channel receptor composed of α1/δ subunits with high potency and α1/γ with a low potency2.
Structure activity relationship studies were done in order to map the major amino acids in α-Conotoxin MI and the overall results show that primarily hydrophobic interactions stabilize the complex between the toxin and the α-δ interface of the nAChR3. Proline-6 and Tyrosine-12 dramatically reduced toxin potency at the high-affinity α/δ site while having comparatively little effect on low-affinity α/γ binding4.
α-Conotoxin MI (#STC-370) is a highly pure, synthetic, and biologically active peptide toxin.