1c49
| |||||||
| Coordinates: | save as pdb, mmCIF, xml | ||||||
STRUCTURAL AND FUNCTIONAL DIFFERENCES OF TWO TOXINS FROM THE SCORPION PANDINUS IMPERATOR
OverviewOverview
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.
About this StructureAbout this Structure
1C49 is a Single protein structure of sequence from Pandinus imperator. Full crystallographic information is available from OCA.
ReferenceReference
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
Page seeded by OCA on Thu Mar 20 10:19:37 2008