“Heteropodatoxin”的意思、由来-开放百科全书

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Heteropodatoxin

释义

Sources
Chemistry
Target
Mode of action
Toxicity
Footnotes
References

Heteropodatoxins are peptide toxins from the venom of the giant crab spider Heteropoda venatoria, which block Kv4.2 voltage-gated potassium channels.

Sources

Heteropodatoxins are purified from the venom of the giant crab spider, Heteropoda venatoria {{Harv |Sanguinetti|1997|}}.

Chemistry

Heteropodatoxins contain an Inhibitor Cystine Knot (ICK) motif, which consist of a compact disulfide-bonded core, from which four loops emerge {{Harv |Bernard|2000|}}. There are three different heteropodatoxins {{Harv |Sanguinetti|1997|}}:

heteropodatoxin-1, also known as Toxin AU3/KJ5 or HpTx1
heteropodatoxin-2, also known as Toxin KJ6 or HpTx2
heteropodatoxin-3, also known as Toxin AU5C/KJ7 or HpTx3

These three toxins are structurally similar peptides of 29-32 amino acids {{Harv |Sanguinetti|1997|}}. They show sequence similarity to Hanatoxins, which can be isolated from the venom of the Chilean rose tarantula Grammostola rosea {{Harv |Sanguinetti|1997|}}.

Target

Heteropodatoxins block A-type, transient voltage-gated potassium channels. All three toxins have been shown to block the potassium channel Kv4.2 {{Harv |Sanguinetti|1997|}}. Recombinant heteropodatoxin-2 blocks the potassium channels Kv4.1, Kv4.2 and Kv4.3, but not Kv1.4, Kv2.1, or Kv3.4 {{Harv |Zarayskiy|2005|}}.

Mode of action

Heterpodatoxin-2 most likely acts as a gating modifier of the Kv4.2 channels {{Harv |Zarayskiy|2005|}}. It shifts the voltage dependence of the activation and the inactivation of the Kv4.3 potassium channel to more positive values. As a result, in the presence of the toxin this channel has a higher probability of being inactivated and a larger depolarization is needed to open the channel. However, heterpodatoxin-2 did not affect the voltage dependence of the Kv4.1 channel, suggesting that the precise mechanism of block remains to be elucidated {{Harv |Zarayskiy|2005|}} and a role as a pore blocker cannot be excluded {{Harv |Bernard|2000|}}. The voltage dependence of Kv4.2 block varies among the three different heteropodatoxins. It is less voltage dependent for HpTx1 than for HpTx2 or HpTx3 {{Harv |Sanguinetti|1997|}}.

Toxicity

The giant crab spider can cause a locally painful bite.^[1]

Footnotes

1. ^{{cite web|last=Edwards|first=G. B.|url=http://entnemdept.ifas.ufl.edu/creatures/urban/spiders/giant_crab_spider.htm|title=huntsman spider - Heteropoda venatoria (Linnaeus)|website=Featured Creatures|date=2009|accessdate=May 11, 2009}}

References

{{cite journal |vauthors=Bernard C, Legros C, Ferrat G, Bischoff U, Marquardt A, Pongs O, Darbon H |title=Solution structure of hpTX2, a toxin from Heteropoda venatoria spider that blocks Kv4.2 potassium channel |journal=Protein Sci. |volume=9 |issue=11 |pages=2059–67 |year=2000 |pmid=11152117 |doi= |pmc=2144494}}{{cite journal |vauthors=Sanguinetti MC, Johnson JH, Hammerland LG, Kelbaugh PR, Volkmann RA, Saccomano NA, Mueller AL |title=Heteropodatoxins: peptides isolated from spider venom that block Kv4.2 potassium channels |journal=Mol. Pharmacol. |volume=51 |issue=3 |pages=491–8 |year=1997 |pmid=9058605 |doi=}}{{cite journal |vauthors=Zarayskiy VV, Balasubramanian G, Bondarenko VE, Morales MJ |title=Heteropoda toxin 2 is a gating modifier toxin specific for voltage-gated K+ channels of the Kv4 family |journal=Toxicon |volume=45 |issue=4 |pages=431–42 |year=2005 |pmid=15733564 |doi=10.1016/j.toxicon.2004.11.015}}

1 : Ion channel toxins

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