 They bind preferentially to the closed or inactivated state of Kv4.2 and Kv4.3 channels.Phrixotoxin-3 (PaurTx3) inhibits several voltage gated sodium channel subtypes (Nav1.1/SCN1A, Nav1.2/SCN2A, Nav1.4/SCN4A, Nav1.5/SCN5A, and Nav1.8/SCN10A) .Phrixotoxins 1 and 2 specifically block Kv4.2 and Kv4.3 channels by altering the voltage-dependent gating properties of these channels.