Antagonist of voltage-gated Cav2.1/CACNA1A (P-type) calcium channels. Paralyzes insect by blocking neuromuscular transmission. Expressed by the venom gland. The presence of a 'disulfide through disulfide knot' structurally defines this protein as a knottin. The toxin with D-Ser (named omega-aga IVC) is 80-90 fold more potent than that with L-Ser (omega-aga IVB) against Cav2.1/CACNA1A (P-type) channels in rat cerebellar Purkinje neurons and is more resistant to proteases. The epimerization is done by the venom peptide isomerase heterodimer. Belongs to the neurotoxin 02 (plectoxin) family. 03 (omega-agtx) subfamily.