title: Slotoxin, alphaKTx1.11, a new scorpion peptide blocker of MaxiK channels that differentiates between alpha and alpha+beta (beta1 or beta4) complexes.
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.
authors.affiliation: Department of Molecular Recognition and Structural Biology, Institute of Biotechnology, National Autonomous University of Mexico, Cuernavaca, Mexico.
authors.forename: J
authors.initials: J
authors.lastname: Garcia-Valdes
authors.forename: F Z
authors.initials: FZ
authors.lastname: Zamudio
authors.forename: L
authors.initials: L
authors.lastname: Toro
authors.forename: L D
authors.initials: LD
authors.lastname: Possani
authors.forename: L D
authors.initials: LD
authors.lastname: Possan
mesh_terms: D000595:Amino Acid Sequence; D002851:Chromatography, High Pressure Liquid; D051037:Large-Conductance Calcium-Activated Potassium Channel alpha Subunits; D051036:Large-Conductance Calcium-Activated Potassium Channels; D008969:Molecular Sequence Data; D026902:Potassium Channel Blockers; D015221:Potassium Channels / Q000737:chemistry; D024681:Potassium Channels, Calcium-Activated; D012604:Scorpion Venoms / Q000737:chemistry* / Q000302:isolation & purification / Q000494:pharmacology*; D017386:Sequence Homology, Amino Acid; D013379:Substrate Specificity
chemical_list: D051037:Large-Conductance Calcium-Activated Potassium Channel alpha Subunits; D051036:Large-Conductance Calcium-Activated Potassium Channels; D026902:Potassium Channel Blockers; D015221:Potassium Channels; D024681:Potassium Channels, Calcium-Activated; D012604:Scorpion Venoms; C437030:alphaKTx1.11