Pi-theraphotoxin-Pc1a - P60514 (TXP1_PSACA)

 

Protein Feature View of PDB entries mapped to a UniProtKB sequence  

  • Number of PDB entries for P60514: 5
 
Function
This toxin is a gating modifier that acts principally as an inhibitor on ASIC1a (ASIC isoform 2) and a potentiator on ASIC1b (ASIC isoform 3) (PubMed:10829030, PubMed:15955877, PubMed:21036899). This toxin potently and selectively inhibits rat, mouse and human ASIC1a (IC(50)=0.35-3.7 nM) (PubMed:10829030, PubMed:15955877, PubMed:21715637, PubMed:26248594, PubMed:21825095). The blockade is rapidly reversible (PubMed:10829030, PubMed:28320941). The toxin acts by shifting its steady-state desensitization to more alkaline pH (0.27 pH unit) (PubMed:15955877, PubMed:16505147). At higher concentrations, it potentiates rat and human ASIC1b and activates chicken ASIC1 by stabilizing the open state of these subtypes (PubMed:16505147, PubMed:21036899, PubMed:19185346, PubMed:24262969, PubMed:22842900). The toxin binds most tightly to the open and the desensitized states of ASIC1a (promoting desensitization), whereas it binds most tightly to the open state of ASIC1b (promoting opening) (PubMed:16505147). The toxin also inhibits mouse ASIC1a-ASIC2b (IC(50)=2.64 nM) and rat ASIC1a-ASIC2a (PubMed:21715637, PubMed:27277303). It binds to the extracellular domain at subunit interfaces in the acidic pocket with the majority of contacts on the thumb domain of the channel (PubMed:21825095, PubMed:22842900, PubMed:22760635). It is also noteworthy that calcium competes with the toxin, probably by inhibiting binding of the toxin to the channel (PubMed:15955877). UniProt
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Domain
The presence of a 'disulfide through disulfide knot' structurally defines this protein as a knottin. UniProt
  • Organism: Trinidad chevron tarantula
  • Length:
  • UniProt
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Data in green originates from UniProtKB  
Variation data (sourced from UniProt) shows non-genetic variation from the ExPASy   and dbSNP   websites.
Data in yellow originates from Pfam  , by interacting with the HMMER3 web site  
Data in purple originates from Phosphosite  .
Data in orange originates from the SCOP   (version 1.75) and SCOPe   (version 2.04) classifications.
Data in grey has been calculated using BioJava  . Protein disorder predictions are based on JRONN (Troshin, P. and Barton, G. J. unpublished), a Java implementation of RONN  
  • Red: potentially disorderd region
  • Blue: probably ordered region.
Hydropathy has been calculated using a sliding window of 15 residues and summing up scores from standard hydrophobicity tables.
  • Red: hydrophobic
  • Blue: hydrophilic.
Data in lilac represent the genomic exon structure projected onto the UniProt sequence.
Data in blue originates from PDB
  • Secstruc: Secondary structure projected from representative PDB entries onto the UniProt sequence.
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Validation Track

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Data in red indicates combined ranges of Homology Models from SBKB   and the Protein Model Portal  
The PDB to UniProt mapping is based on the data provided by the EBI SIFTS project. See also Velankar et al., Nucleic Acids Research 33, D262-265 (2005).
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