Overview
- Martinez, J.S. et al. (1995) Biochemistry 34, 14519.
Alomone Labs α-Conotoxin EI inhibits α1/β1/γ/δ nAChR channels heterologously expressed in Xenopus oocytes.A. Time course of α-Conotoxin EI (#STC-900) 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 and 3 µM PNU-120596 stimulation every 100 seconds. 0.5 µM (for 4.5 min, green) and 1 µM (for 4.5 min, red) α-Conotoxin EI was perfused during the period marked by the bar, as indicated. B. Superimposed traces of muscle nAChR channel current in the absence (black) and presence of 0.5 µM (green) or 1 µM (red) α-Conotoxin EI (taken from the experiment in A).
The nicotinic acetylcholine receptors (nAChRs) are a family of ligand-gated ion channels that are widely expressed throughout the central and peripheral nervous systems. The best characterized nAChR is the receptor at the neuromuscular junction, with four different subunits in a pentameric array, (α1)2β1γδ1.
Small peptide toxins of Conus origin known as the Aα-conotoxins are highly useful tools for exploring ligand nAChR interactions. α-Conotoxins are known to be selective and potent competitive antagonists of nicotinic acetylcholine receptors2.
α-Conotoxin EI is a 18 amino acid peptidyl toxin, originally isolated from the Conus ermineus (Athlantic fish-hunting cone) venom. In Torpedo nAChRs, α-conotoxin EI selectively binds the agonist site near the α/δ subunit interface. In mammalian nAChRs α-conotoxin EI shows high affinity for both the α/δ and α/γ subunit interfaces (with some preference for the α/δ site)3.
The unique binding preference of α-conotoxin EI to the α/δ subunit interface makes it a valuable structural template for superposition of various α-conotoxin possessing distinct receptor subtype specificities4.
