Selectively activates mammalian TRPV1, or capsaicin receptor, a non-selective cation channel expressed by sensory neurons of the pain pathway. Is more potent than VaTx1 and VaTx2. 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. In mice, elicits pain-related behaviors, such as licking and flinching of the affected limb. The paw of toxin-injected mice shows substantial edema. Expressed by the venom gland. The presence of a 'disulfide through disulfide knot' structurally defines this protein as a knottin. This toxin does not affect TRPV2, TRPV3, TRPV4, TRPA1, TRPM8, Kv1.2/KCNA2, Kv2.1/KCNB1 and Kv4.2/KCND2 potassium channels. Belongs to the neurotoxin 10 (Hwtx-1) family. 62 (Vatx) subfamily.