1c49

STRUCTURAL AND FUNCTIONAL DIFFERENCES OF TWO TOXINS FROM THE SCORPION PANDINUS IMPERATOR

spinqualitylabelsall models 1c49, 18 NMR models Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 1c49 is a 1 chain structure. Full experimental information is available from OCA. For a guided tour on the structure components use FirstGlance. Resources: FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT Function [KAX72_PANIM] Potent inhibitor of the A-type voltage-gated potassium channels. Most potent inhibitor of Kv1.2/KCNA2 channels. Reversibly block the Shaker B potassium-channels (Kv1.1 sub-family), but with a lower affinity than PiTX-K alpha. Publication Abstract from PubMed The Pandinotoxins, PiTX-K alpha and PiTX-K beta, are members of the Charybdotoxin family of scorpion toxins that can be used to characterize K+ channels. PiTX-K alpha differs from PiTX-K beta, another peptide from Pandinus imperator, by one residue (P10E). When the two toxins are compared in a physiological assay, the affinity of PiTX-K beta for voltage-gated, rapidly inactivating K+ channels in dorsal root ganglia (DRG) neurons is 800-fold lower than that of PiTX-K alpha (K alpha-IC50 = 8.0 nM versus K beta-IC50 = 6,500 nM). To understand this difference, the three-dimensional structure of PiTX-K beta was determined by nuclear magnetic resonance (NMR) spectroscopy and compared to that of PiTX-K alpha. This comparison shows that structural differences between the two toxins occur at a residue that is critical for blocking K+ channels (K27) as well as at the site of the natural mutation (P10E). In PiTX-K beta, the negatively charged carboxylate oxygen of E10 can approach the positive charge of K27 and presumably reduces the net positive charge in this region of the toxin. This is likely the reason why PiTX-K beta binds K+ channels from DRG neurons with a much lower affinity than does PiTX-K alpha. Structural and functional differences of two toxins from the scorpion Pandinus imperator.,Klenk KC, Tenenholz TC, Matteson DR, Rogowski RS, Blaustein MP, Weber DJ Proteins. 2000 Mar 1;38(4):441-9. PMID:10707030 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See Also Potassium channel toxin

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