Selectively activates the mammalian capsaicin receptor TRPV1, a non-selective cation channel expressed by sensory neurons of the pain pathway. Is more potent than VaTx1, but less potent than VaTx3. Interacts with distinct regions of the channel than capsaicin, since it only acts on the extracellular face of the channel, and capsaicin binds to the cytosolic side. Also activates avian TRPV1, which is insensitive to capsaicin. Produce weak inhibition on potassium channels Kv2.1/KCNB1. Expressed by the venom gland. The presence of a 'disulfide through disulfide knot' structurally defines this protein as a knottin. This toxin does not have effect on TRPV2, TRPV3, TRPV4, TRPA1, TRPM8, Kv1.2/KCNA2 or Kv4.2/KCND2. Belongs to the neurotoxin 10 (Hwtx-1) family. 62 (Vatx) subfamily.