Selectively activates mammalian TRPV1, the capsaicin receptor, a non-selective cation channel expressed by sensory neurons of the pain pathway. Is less potent than VaTx2 and 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. Significantly inhibits 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 and Kv4.2/KCND2. Belongs to the neurotoxin 10 (Hwtx-1) family. 62 (Vatx) subfamily.