==Crystal structure of Aplysia californica AChBP in complex with alpha- conotoxin ImI==

<StructureSection load='2byp' size='340' side='right'caption='[[2byp]], [[Resolution|resolution]] 2.07&Aring;' scene=''>

<table><tr><td colspan='2'>[[2byp]] is a 10 chain structure with sequence from [http://en.wikipedia.org/wiki/Aplca Aplca]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=2BYP OCA]. For a <b>guided tour on the structure components</b> use [http://oca.weizmann.ac.il/oca-docs/fgij/fg.htm?mol=2BYP FirstGlance]. <br>

</td></tr><tr id='ligand'><td class="sblockLbl"><b>[[Ligand|Ligands:]]</b></td><td class="sblockDat"><scene name='pdbligand=NAG:N-ACETYL-D-GLUCOSAMINE'>NAG</scene></td></tr>

<tr id='resources'><td class="sblockLbl"><b>Resources:</b></td><td class="sblockDat"><span class='plainlinks'>[http://oca.weizmann.ac.il/oca-docs/fgij/fg.htm?mol=2byp FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=2byp OCA], [http://pdbe.org/2byp PDBe], [http://www.rcsb.org/pdb/explore.do?structureId=2byp RCSB], [http://www.ebi.ac.uk/pdbsum/2byp PDBsum], [http://prosat.h-its.org/prosat/prosatexe?pdbcode=2byp ProSAT]</span></td></tr>

== Function ==

[[http://www.uniprot.org/uniprot/CA1_CONIM CA1_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.<ref>PMID:8206995</ref>

<div style="background-color:#fffaf0;">

== Publication Abstract from PubMed ==

Upon ligand binding at the subunit interfaces, the extracellular domain of the nicotinic acetylcholine receptor undergoes conformational changes, and agonist binding allosterically triggers opening of the ion channel. The soluble acetylcholine-binding protein (AChBP) from snail has been shown to be a structural and functional surrogate of the ligand-binding domain (LBD) of the receptor. Yet, individual AChBP species display disparate affinities for nicotinic ligands. The crystal structure of AChBP from Aplysia californica in the apo form reveals a more open loop C and distinctive positions for other surface loops, compared with previous structures. Analysis of Aplysia AChBP complexes with nicotinic ligands shows that loop C, which does not significantly change conformation upon binding of the antagonist, methyllycaconitine, further opens to accommodate the peptidic antagonist, alpha-conotoxin ImI, but wraps around the agonists lobeline and epibatidine. The structures also reveal extended and nonoverlapping interaction surfaces for the two antagonists, outside the binding loci for agonists. This comprehensive set of structures reflects a dynamic template for delineating further conformational changes of the LBD of the nicotinic receptor.

Structures of Aplysia AChBP complexes with nicotinic agonists and antagonists reveal distinctive binding interfaces and conformations.,Hansen SB, Sulzenbacher G, Huxford T, Marchot P, Taylor P, Bourne Y EMBO J. 2005 Oct 19;24(20):3635-46. Epub 2005 Sep 29. PMID:16193063<ref>PMID:16193063</ref>

From MEDLINE&reg;/PubMed&reg;, a database of the U.S. National Library of Medicine.<br>

</div>

<div class="pdbe-citations 2byp" style="background-color:#fffaf0;"></div>

==See Also==

*[[Acetylcholine binding protein 3D structures|Acetylcholine binding protein 3D structures]]

== References ==

<references/>

[[Category: Aplca]]

[[Category: Bourne, Y]]

[[Category: Receptor complex]]