Spider Toxin Card | ArachnoServer

Toxin Name	π-theraphotoxin-Pc1a
Source Species	*Psalmopoeus cambridgei* (Trinidad chevron tarantula)
Toxin Group	Theraphotoxin
Description	π-TRTX-Pc1a potently and selectively blocks the proton-gated sodium channel ASIC1a (acid-sensitive ion channel 1a). The blockade is rapid and reversible. The toxin increases the affinity of ASIC1a for protons. π-TRTX-Pc1a loses its capacity to block ASIC1a as soon as this subunit is associated with another member of the ASIC family (ASIC2a or ASIC3). The toxin can distinguish between the two ASIC1 splice variants ASIC1a and ASIC1b. For ASIC1b, the toxin binds most tightly to the open state, promoting opening, whereas for ASIC1a, it binds most tightly to the open and desensitized state, promoting desensitization. The toxin binds to the cysteine rich domains (CRD I and CRD II) of the extracellular region of the ASIC1a channel.
Discovered	2000

Sex: Female, Prosoma length: 25mm
Photo courtesy of Bastian Rast
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This toxin last updated on Jul 21, 2010

Taxonomy

Biological Activity

Accessions

Literature References

Original Deposition References
Escoubas P., de Weille J.R., Lecoq A., Diochot S., Waldmann R., Champigny G., Moinier D., Menez A., Lazdunski M. J. Biol. Chem. 275:25116-25121(2000). Isolation of a tarantula toxin specific for a class of proton-gated Na+ channels.
Escoubas P., Bernard C., Lambeau G., Lazdunski M., Darbon H. Protein Sci. 12:1332-1343(2003). Recombinant production and solution structure of PcTx1, the specific peptide inhibitor of ASIC1a proton-gated cation channels.
Other References
Chen X., Kalbacher H., Gründer S. J. Gen. Physiol. 126:71-79(2005). The tarantula toxin psalmotoxin 1 inhibits acid-sensing ion channel (ASIC) 1a by increasing its apparent H+ affinity.
Chen X., Kalbacher H., Gründer S. J. Gen. Physiol. 127:267-276(2006). Interaction of acid-sensing ion channel (ASIC) 1 with the tarantula toxin psalmotoxin 1 is state dependent.
Salinas M., Rash L.D., Baron A., Lambeau G., Escoubas P., Lazdunski M. J. Physiol. (Lond.) 570:339-354(2006). The receptor site of the spider toxin PcTx1 on the proton-gated cation channel ASIC1a.
Lazdunski M., Escoubas P., DeWeille J., Diochot S. Patent number US 7132505, 07-NOV-2006. Polypeptide inhibiting a proton-gated Na+ channel, a nucleic acid coding for such polypeptide and a method of manufacturing an ASIC1a channel blocker
Mazzuca M., Heurteaux C., Alloui A., Diochot S., Baron A., Voilley N., Blondeau N., Escoubas P., Gélot A., Cupo A., Zimmer A., Zimmer A.M., Eschalier A., Lazdunski M. Nat. Neurosci. 10:943-945(2007). A tarantula peptide against pain via ASIC1a channels and opioid mechanisms.

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