1imi | pdb_00001imi
SOLUTION STRUCTURE OF ALPHA-CONOTOXIN IM1
Structural highlights
FunctionCA1_CONIM Alpha-conotoxins act on postsynaptic membranes, they bind to the nicotinic acetylcholine receptors (nAChR) and thus inhibit them. This toxin blocks mammalian neuronal nAChRs (alpha-3/beta-2 > alpha-7 > alpha-3/beta-4). Has no effect on nAChRs composed of alpha-2/beta-2, alpha-3/beta-2, alpha-4/beta-2, alpha-2/beta-4, alpha-3/beta-4, or alpha-4/beta-4 subunits. Acts voltage-independently. Is highly active against the neuromuscular receptor in frog.[1] Publication Abstract from PubMedA 600 MHz NMR study of alpha-conotoxin ImI from Conus imperialis, targeting the alpha7 neuronal nicotinic acetylcholine receptor (nAChR), is presented. ImI backbone spatial structure is well defined basing on the NOEs, spin-spin coupling constants, and amide protons hydrogen-deuterium exchange data: rmsd of the backbone atom coordinates at the 2-12 region is 0.28 A in the 20 best structures. The structure is described as a type I beta-turn (positions 2-5) followed by a distorted helix (positions 5-11). Similar structural patterns can be found in all neuronal-specific alpha-conotoxins. Highly mobile side chains of the Asp-5, Arg-7 and Trp-10 residues form a single site for ImI binding to the alpha7 receptor. When depicted with opposite directions of the polypeptide chains, the ImI helix and the tip of the central loop of long chain snake neurotoxins demonstrate a common scaffold and similar positioning of the functional side chains, both of these structural elements appearing essential for binding to the neuronal nAChRs. NMR spatial structure of alpha-conotoxin ImI reveals a common scaffold in snail and snake toxins recognizing neuronal nicotinic acetylcholine receptors.,Maslennikov IV, Shenkarev ZO, Zhmak MN, Ivanov VT, Methfessel C, Tsetlin VI, Arseniev AS FEBS Lett. 1999 Feb 12;444(2-3):275-80. PMID:10050774[2] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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