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XB-ART-53127
Biochim Biophys Acta Proteins Proteom 2017 May 01;18655:465-472. doi: 10.1016/j.bbapap.2017.02.001.
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C-Terminal residues in small potassium channel blockers OdK1 and OSK3 from scorpion venom fine-tune the selectivity.

Kuzmenkov AI , Peigneur S , Chugunov AO , Tabakmakher VM , Efremov RG , Tytgat J , Grishin EV , Vassilevski AA .


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We report isolation, sequencing, and electrophysiological characterization of OSK3 (α-KTx 8.8 in Kalium and Uniprot databases), a potassium channel blocker from the scorpion Orthochirus scrobiculosus venom. Using the voltage clamp technique, OSK3 was tested on a wide panel of 11 voltage-gated potassium channels expressed in Xenopus oocytes, and was found to potently inhibit Kv1.2 and Kv1.3 with IC50 values of ~331nM and ~503nM, respectively. OdK1 produced by the scorpion Odontobuthus doriae differs by just two C-terminal residues from OSK3, but shows marked preference to Kv1.2. Based on the charybdotoxin-potassium channel complex crystal structure, a model was built to explain the role of the variable residues in OdK1 and OSK3 selectivity.

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Species referenced: Xenopus
Genes referenced: kcna2 kcna3