1wqc

An unusual fold for potassium channel blockers : NMR structure of three toxins from the scorpion Opisthacanthus madagascariensis

spinqualitylabelsall models 1wqc Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 1wqc is a 1 chain structure with sequence from Opisthacanthus madagascariensis. Full experimental information is available from OCA. For a guided tour on the structure components use FirstGlance. Method: Solution NMR Resources: FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT Function KKX21_OPIMA OmTx1 decreases the amplitude of the potassium current of the rat channels Kv1.1/KCNA1 by 17% and Kv1.2/KCNA2 by 12% as well as human Kv1.3/KCNA3 by 24%. OmTx2 decreases the amplitude of the potassium current of the rat channels Kv1.1/KCNA1 by 8% and Kv1.2/KCNA2 by 10% as well as human Kv1.3/KCNA3 by 36%. Also alters glucose-induced insulin release from pancreatic islets. Publication Abstract from PubMed The Om-toxins are short peptides (23-27 amino acids) purified from the venom of the scorpion Opisthacanthus madagascariensis. Their pharmacological targets are thought to be potassium channels. Like Csalpha/beta (cystine-stabilized alpha/beta) toxins, the Om-toxins alter the electrophysiological properties of these channels; however, they do not share any sequence similarity with other scorpion toxins. We herein demonstrate by electrophysiological experiments that Om-toxins decrease the amplitude of the K+ current of the rat channels Kv1.1 and Kv1.2, as well as human Kv1.3. We also determine the solution structure of three of the toxins by use of two-dimensional proton NMR techniques followed by distance geometry and molecular dynamics. The structures of these three peptides display an uncommon fold for ion-channel blockers, Csalpha/alpha (cystine-stabilized alpha-helix-loop-helix), i.e. two alpha-helices connected by a loop and stabilized by two disulphide bridges. We compare the structures obtained and the dipole moments resulting from the electrostatic anisotropy of these peptides with those of the only other toxin known to share the same fold, namely kappa-hefutoxin1. An unusual fold for potassium channel blockers: NMR structure of three toxins from the scorpion Opisthacanthus madagascariensis.,Chagot B, Pimentel C, Dai L, Pil J, Tytgat J, Nakajima T, Corzo G, Darbon H, Ferrat G Biochem J. 2005 May 15;388(Pt 1):263-71. PMID:15631621 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See Also Potassium channel toxin 3D structures

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