Ion channel impairing toxin that inhibits voltage-gated calcium channel Cav3.1/CACNA1G (IC(50)=53 nM), voltage-gated potassium channels Kv2.1/KCNB1 (IC(50)=411 nM), all sodium channels tested (Nav1.2/SCN2A (IC(50)=60-104 nM), Nav1.5/SCN5A (IC(50)=76-358 nM), Nav1.6/SCN8A (IC(50)=21-133 nM), Nav1.7/SCN9A (IC(50)=51-95 nM), and Nav1.8/SCN10A) and the nociceptor cation channel TRPA1 (IC(50)=389 nM) (PubMed:12475222, PubMed:17087985, PubMed:20351484, PubMed:24886690, PubMed:29703751, PubMed:31234412, PubMed:24530065). Acts as a potent and selective blocker of voltage-gated calcium channel Cav3.1/CACNA1G, but not of Cav3.2/CACNA1H, and Cav3.3/CACNA1I (PubMed:20351484, PubMed:24886690). On Nav1.7/SCN9A, primarily interacts with the DII and DIV voltage-sensor domains (PubMed:32511987). Also acts as an inhibitor of nociceptor cation channel TRPA1 (IC(50)~389 nM) by binding to the S1-S4 gating domain of TRPA1 (PubMed:24530065). It shows moderate affinity for lipid bilayers (PubMed:29703751). Expressed by the venom gland. The presence of a 'disulfide through disulfide knot' structurally defines this protein as a knottin. An unnatural amidation at Ser-35 provokes a 14-fold increased toxin ability to inhibit Nav1.2/SCN2A and a ~2-fold decreased toxin ability to inhibit both Nav1.5/SCN5A and Nav1.6/SCN8A. The amidated mutant G32A (ProTx-I-G32A-NH2) shows a decreased ability to inhibit all sodium channels tested, with a more pronounced reduction on Nav1.2/SCN2A and Nav1.5/SCN5A. As a consequence, this mutant shows an enhanced selectivity and potency for Nav1.7/SCN9A, and thus may provide a good starting point for second generation analogs to treat pain. The primary structure of the mature peptide is identical to that of Beta/omega-theraphotoxin-Bp1a from Bumba pulcherrimaklaasi (AC P0DQN3). Belongs to the neurotoxin 10 (Hwtx-1) family. 54 (ProTx-1) subfamily.