Inhibits P/Q- (Cav2.1/CACNA1A) and N-type (Cav2.2/CACNA1B) voltage-gated calcium channel by modifying voltage-dependent gating (PubMed:9415720, PubMed:29483648). It selectively and reversibly blocks the calcium channels coupled to glutamate release (PubMed:8848236). Also inhibits potassium channels (Kv2.1/KCNB1) with lower affinity (PubMed:9671721, PubMed:29483648). Has also been shown to weakly inhibit Kv11.1/KCNH2/ERG1, Kv1.2/KCNA2, Kv1.3/KCNA3, Nav1.5/SCN5A, Nav1.7/SCN9A and TRPV1 (PubMed:29483648). Expressed by the venom gland. The presence of a 'disulfide through disulfide knot' structurally defines this protein as a knottin. Belongs to the neurotoxin 10 (Hwtx-1) family. 07 (GrTx) subfamily.