Abstract
A novel peptide from Centruroides noxius Hoffmann scorpion venom was isolated and sequenced. The 37 amino acid peptide belongs to the charybdotoxin sub-family (alphaKTx1) and was numbered member 11. alphaKTx1.11 has 75% sequence identity with iberiotoxin and 54% with charybdotoxin. alphaKTx1.11 revealed specificity for mammalian MaxiK channels (hSlo), thus, was named slotoxin. Slotoxin blocks the MaxiK pore-forming alpha subunit reversibly (K(d)=1.5 nM). Slotoxin association with alpha+beta (beta1 or beta4) channels was approximately 10 times slower than iberiotoxin and charybdotoxin, leading to a lack of effect on alpha+beta4 when tested at 100 nM for 5 min. Thus, slotoxin is a better tool to distinguish MaxiK alpha+beta complexes.
Publication types
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Research Support, Non-U.S. Gov't
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Research Support, U.S. Gov't, Non-P.H.S.
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Research Support, U.S. Gov't, P.H.S.
MeSH terms
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Amino Acid Sequence
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Chromatography, High Pressure Liquid
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Large-Conductance Calcium-Activated Potassium Channel alpha Subunits
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Large-Conductance Calcium-Activated Potassium Channels
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Molecular Sequence Data
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Potassium Channel Blockers*
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Potassium Channels / chemistry
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Potassium Channels, Calcium-Activated*
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Scorpion Venoms / chemistry*
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Scorpion Venoms / isolation & purification
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Scorpion Venoms / pharmacology*
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Sequence Homology, Amino Acid
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Substrate Specificity
Substances
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Large-Conductance Calcium-Activated Potassium Channel alpha Subunits
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Large-Conductance Calcium-Activated Potassium Channels
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Potassium Channel Blockers
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Potassium Channels
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Potassium Channels, Calcium-Activated
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Scorpion Venoms
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alphaKTx1.11