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Background
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Vanillotoxin-3 (VaTx3) has been isolated from the venom of Psalmopoeus cambridgei, a West Indies tarantula. It is a 34 amino acids peptide with three disulfide bridges with an ICK motif. It selectively activates mammalian TRPV1 (capsaicin receptor), a non-selective cation channel expressed by sensory neurons of the pain pathway with an EC50 value of 0.45 ± 0.04 µM. It is more potent than VaTx1 (20-fold) and VaTx2 (2-fold), two other analogues of VaTx3 with closely related sequences and isolated from the same venom. VaTx3 probably interacts with distinct regions of the channel than capsaicin. VaTx3 does not affect TRPV2, TRPV3, TRPV4, TRPA1, TRPM8, Kv1.2 (KCNA2), Kv2.1 (KCNB1) or Kv4.2 (KCND2). In mice, VaTx3 elicits pain-related behaviors, such as licking and flinching of the affected limb. Edema is evidenced in the paw of toxin-injected mice.
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