Omega-agatoxins inhibit neuronal voltage-gated calcium channels. This toxin acts by modifying the gating of the high voltage activated P-type Cav2.1/CACNA1A channel. Is a potent blocker in both insect and mammalian central neurons. Expressed by the venom gland. The presence of a 'disulfide through disulfide knot' structurally defines this protein as a knottin. This toxin is a diagnostic ligand for P-type channels Ca2.1/CACNA1A in the mammalian brain. The binding site for this toxin has been localized in part to the extracellular S3-S4 loop in repeat IV of the alpha1 subunit of mammalian Cav2.1/CACNA1A channels, which is proximal to the S4 sensor domain. Belongs to the neurotoxin 02 (plectoxin) family. 03 (omega-agtx) subfamily.