JZTX-XIII, a Kv channel gating modifier toxin from Chinese tarantula Chilobrachys jingzhao

► JZTX-XIII acts as gating modifier of voltage-gated K+ channels. ► JZTX-XIII potently inhibits Kv2.1 and Kv4.1 channels. ► JZTX-XIII shows no Nav1.5 channel activity. ► Residues of Glu10 and Glu17 in JZTX-XIII might impair the binding to Nav1.5 channel.