Phrixotoxin-2

Phrixotoxin-2 (PaTx2) has been isolated originally from the venom of the Chile fire tarantula Phrixotrichus auratus. Phrixotoxin-2 is a 31 amino acid peptide that contains three disulfide bridges. Phrixotoxin-2 specifically blocks recombinant Kv4.2 and Kv4.3 currents with IC50 values of 34 nM and 71 nM, respectively. It does so by altering the gating properties of the channels. The inhibition of Kv4.2 and Kv4.3 currents is fully reversible upon washout. Kv4.1 is only slightly sensitive to Phrixotoxin-2 (maximal block of 20 by 300 nM) . Kv1, Kv2 and Kv3 channel subfamilies are insensitive to this toxin.