Kunitz-type neurotoxin MitTx-alpha - G9I929 (VKTA_MICTN)


Protein Feature View of PDB entries mapped to a UniProtKB sequence  

  • Number of PDB entries for G9I929: 3
MitTx, a heteromeric complex between Kunitz- and phospholipase-A2-like proteins, potently, persistently and selectively activates rat and chicken acid-sensing ion channel ASIC1 (PubMed:22094702, PubMed:24507937). Both alternatively spliced rat isoforms ASIC1a and ASIC1b are activated, with a higher potency for ASIC1a (EC(50)=9.4 nM) vs ASIC1b (EC(50)=23 nM) (PubMed:22094702). The rat ASIC3 subtype is also sensitive to the heterodimer, but with a lower potency (EC(50)=830 nM) (PubMed:22094702). On rat ASIC2a, the toxin shows a very weak activation, but produces a remarkable potentiation (>100-fold) of protons when the extracellular pH drops below neutrality (PubMed:22094702). Moderate and weak activations are also observed on the heterotrimers Asic1a-Asic2a and Asic1a-Asic3 (expressed in CHO cells), respectively (PubMed:22094702). The binding sites of the beta subunit of MitTx and the spider psalmotoxin-1 overlap, explaining why these toxins are mutually exclusive (PubMed:22094702. PubMed:24507937). In vivo, the heterodimer elicits robust pain-related behavior in mice by activation of ASIC1 channels on capsaicin-sensitive nerve fibers (PubMed:22094702). UniProt
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Subunit Structure
Heterodimer of an alpha (Kunitz-type) and a beta (phospholipase A2 homolog) chains; non-covalently-linked. UniProt
The toxin-channel complex has a triskelion-like shape with one toxin heterodimer radiating from each ASIC1 subunit. Toxin subunits protrude from the edges of the channel trimer, with each heterodimer interacting almost exclusively with a single subunit. UniProt
  • Organism: Texas coral snake
  • Length:
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