Overview
Alomone Labs Jingzhaotoxin-XII inhibits KV4.1 currents in transiently transfected HEK293T cells.A. Time course of Jingzhaotoxin-XII (#STJ-100) action. Peak current amplitude was plotted as a function of time. Holding potential was -100 mV and currents were stimulated every 20 seconds by a voltage step of 80 msec from holding potential to 0 mV. 2 µM Jingzhaotoxin-XII was perfused in the period marked by the horizontal bar (green), indicating the inhibitory effect of Jingzhaotoxin-XII. B. Superimposed traces of KV4.1 currents under control conditions and after 3 min application of 2 µM Jingzhaotoxin-XII (green, as indicated).
Voltage-gated K+ (KV) channels play important roles in regulating the excitability of myocytes and neurons. KV channel α subunits are divided into four major subfamilies, KV1 through KV41. The KV4 (Shal) subfamily comprises three distinct genes, KV4.1, KV4.2, and KV4.32.
Voltage-gated Na+ channels play an important role in generating action potentials. NaV channels consists nine different α subunits, NaV1.1 through NaV1.93.
Jingzhaotoxin-XII (JZTX-XII), a 29-residue polypeptide, isolated from the venom of Chinese tarantula Chilobrachys jingzhao. JZTX-XII is specific for the Kv4.1 channel and has high selectivity to the NaV channel isoform expressed in cardiac myocytes. It interacts with the channels by modifying the gating behavior4. JZTX-XII blocks KV4.1 currents with an IC50 value of 363 nM in X. laevis oocytes5 and can inhibit NaV1.5 with an IC50 value of 348 nM6.
