Psalmotoxin-1 (PcTx1) has been isolated from the venom of the Spider Psalmopoeus cambridgei (Trinidad chevron tarantula). This toxin blocks potently and selectively the H+-gated sodium channel ASIC1a (acid-sensitive ion channel 1a). The blockage is rapid and reversible. Psalmotoxin 1 loses its capacity to block ASIC1a as soon as this subunit is associated with another member of the family (ASIC2a or ASIC3). The toxin can distinguish between the two ASIC1 splice variants ASIC1a and ASIC1b.
Peptides & proteins
Lazdunski, M., et al. (2000) Isolation of a tarantula toxin specific for a class of proton-gated Na+ channels, J Biol Chem; Darbon, H., et al. (2003) Recombinant production and solution structure of PcTx1, the specific peptide inhibitor of ASIC1a proton-gated cation channels, Protein Sci