1akg

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[[Image:1akg.gif|left|200px]]
 
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==ALPHA-CONOTOXIN PNIB FROM CONUS PENNACEUS==
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The line below this paragraph, containing "STRUCTURE_1akg", creates the "Structure Box" on the page.
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<StructureSection load='1akg' size='340' side='right'caption='[[1akg]], [[Resolution|resolution]] 1.10&Aring;' scene=''>
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== Structural highlights ==
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or the SCENE parameter (which sets the initial scene displayed when the page is loaded),
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<table><tr><td colspan='2'>[[1akg]] is a 1 chain structure with sequence from [https://en.wikipedia.org/wiki/Conus_pennaceus Conus pennaceus]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1AKG OCA]. For a <b>guided tour on the structure components</b> use [https://proteopedia.org/fgij/fg.htm?mol=1AKG FirstGlance]. <br>
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</td></tr><tr id='method'><td class="sblockLbl"><b>[[Empirical_models|Method:]]</b></td><td class="sblockDat" id="methodDat">X-ray diffraction, [[Resolution|Resolution]] 1.1&#8491;</td></tr>
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<tr id='ligand'><td class="sblockLbl"><b>[[Ligand|Ligands:]]</b></td><td class="sblockDat" id="ligandDat"><scene name='pdbligand=NH2:AMINO+GROUP'>NH2</scene></td></tr>
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{{STRUCTURE_1akg| PDB=1akg | SCENE= }}
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<tr id='resources'><td class="sblockLbl"><b>Resources:</b></td><td class="sblockDat"><span class='plainlinks'>[https://proteopedia.org/fgij/fg.htm?mol=1akg FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=1akg OCA], [https://pdbe.org/1akg PDBe], [https://www.rcsb.org/pdb/explore.do?structureId=1akg RCSB], [https://www.ebi.ac.uk/pdbsum/1akg PDBsum], [https://prosat.h-its.org/prosat/prosatexe?pdbcode=1akg ProSAT]</span></td></tr>
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</table>
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== Function ==
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[https://www.uniprot.org/uniprot/CA1B_CONPE CA1B_CONPE] Alpha-conotoxins act on postsynaptic membranes, they bind to the nicotinic acetylcholine receptors (nAChR) and thus inhibit them. This toxin blocks mammalian nAChRs (alpha-7 > alpha-3/beta-2).<ref>PMID:10545176</ref>
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<div style="background-color:#fffaf0;">
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== Publication Abstract from PubMed ==
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Conotoxins are small, cysteine-rich peptides isolated from the venom of Conus spp. of predatory marine snails, which selectively target specific receptors and ion channels critical to the functioning of the neuromuscular system. alpha-Conotoxins PnIA and PnIB are both 16-residue peptides (differing in sequence at only two positions) isolated from the molluscivorous snail Conus pennaceus. In contrast to the muscle-selective alpha-conotoxin GI from Conus geographus, PnIA and PnIB block the neuronal nicotinic acetylcholine receptor (nAChR). Here, we describe the crystal structure of PnIB, solved at a resolution of 1.1 A and phased using the Shake-and-Bake direct methods program. PnIB crystals are orthorhombic and belong to the space group P212121 with the following unit cell dimensions: a = 14.6 A, b = 26.1 A, and c = 29.2 A. The final refined structure of alpha-conotoxin PnIB includes all 16 residues plus 23 solvent molecules and has an overall R-factor of 14.7% (R-free of 15.9%). The crystal structures of the alpha-conotoxins PnIB and PnIA are solved from different crystal forms, with different solvent contents. Comparison of the structures reveals them to be very similar, showing that the unique backbone and disulfide architecture is not strongly influenced by crystal lattice constraints or solvent interactions. This finding supports the notion that this structural scaffold is a rigid support for the presentation of important functional groups. The structures of PnIB and PnIA differ in their shape and surface charge distribution from that of GI.
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'''ALPHA-CONOTOXIN PNIB FROM CONUS PENNACEUS'''
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Crystal structure at 1.1 A resolution of alpha-conotoxin PnIB: comparison with alpha-conotoxins PnIA and GI.,Hu SH, Gehrmann J, Alewood PF, Craik DJ, Martin JL Biochemistry. 1997 Sep 23;36(38):11323-30. PMID:9298951<ref>PMID:9298951</ref>
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From MEDLINE&reg;/PubMed&reg;, a database of the U.S. National Library of Medicine.<br>
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==Overview==
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</div>
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Two mollusc-specific neurotoxic peptides from the venom of the molluscivorous snail Conus pennaceus are described. These new toxins block acetylcholine receptors (AChR) of cultured Aplysia neurons. Bath application of 0.5-1 microM toxin induces 5-10-mV membrane depolarization, which recovers to the control level within 1-3 min in the presence of the toxin. This response is blocked by 1 mM hexamethonium. Concomitantly with the transient depolarization, the toxins block approximately 90% of the depolarizing responses evoked by brief iontophoretic application of acetylcholine. The pharmacology and amino acid sequences of the toxins (alpha PnIA, GCCSLPPCAANNPDYC-NH2; alpha PnIB, GCCSLPPCALSNPDYC-NH2) enable their classification as novel alpha-conotoxins. The sequences differ from those of previously described alpha-conotoxins in a number of features, the most striking of which is the presence of a single negatively charged residue in the C-terminal loop. This loop contains a positively charged residue in piscivorous venom alpha-conotoxins. In contrast to other alpha-conotoxins, which are selective for vertebrate skeletal muscle nicotinic ACh receptors, these Conus pennaceus toxins block neuronal ACh receptors in molluscs. As such they are new probes which can be used to define subtypes of ACh receptors, and they should be useful tools in the study of structure-function relationships in ACh receptors.
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<div class="pdbe-citations 1akg" style="background-color:#fffaf0;"></div>
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== References ==
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==About this Structure==
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<references/>
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1AKG is a [[Single protein]] structure of sequence from [http://en.wikipedia.org/wiki/Conus_pennaceus Conus pennaceus]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1AKG OCA].
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__TOC__
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</StructureSection>
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==Reference==
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New mollusc-specific alpha-conotoxins block Aplysia neuronal acetylcholine receptors., Fainzilber M, Hasson A, Oren R, Burlingame AL, Gordon D, Spira ME, Zlotkin E, Biochemistry. 1994 Aug 16;33(32):9523-9. PMID:[http://www.ncbi.nlm.nih.gov/pubmed/8068627 8068627]
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[[Category: Conus pennaceus]]
[[Category: Conus pennaceus]]
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[[Category: Single protein]]
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[[Category: Large Structures]]
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[[Category: Hu, S H.]]
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[[Category: Hu S-H]]
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[[Category: Martin, J L.]]
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[[Category: Martin JL]]
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[[Category: Acetylcholine receptor antagonist]]
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[[Category: Alpha-conotoxin]]
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[[Category: Crystal structure]]
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''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Fri May 2 10:23:07 2008''
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ALPHA-CONOTOXIN PNIB FROM CONUS PENNACEUS

PDB ID 1akg

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