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2  structures 0  species 0  interactions 0  sequences 0  architectures

Family: Toxin_5 (PF05294)

Summary: Scorpion short toxin

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This is the Wikipedia entry entitled "Scorpion toxin". More...

Scorpion toxin Edit Wikipedia article

Scorpion long-chain toxin
Crystal structure of toxin II from the scorpion Androctonus australis Hector.[1]
Symbol Toxin_3
Pfam PF00537
InterPro IPR002061
SCOP 2sn3
OPM superfamily 61
OPM protein 1djt
Scorpion short toxin
Agitoxin-2. Disulphide bonds are highlighted. PDB 1agt [2]
Symbol Toxin_2
Pfam PF00451
Pfam clan CL0054
InterPro IPR001947

Scorpion toxins are proteins found in the venom of scorpions. Their toxic effect may be mammal or insect specific, and acts by binding to sodium channels, inhibiting the inactivation of activated channels and blocking neuronal transmission.

The family includes related short- and long-chain scorpion toxins. It also contains a group of proteinase inhibitors from the plants Arabidopsis thaliana and Brassica spp.

The Brassica napus (Oil seed rape) and Sinapis alba (White mustard) inhibitors,[3][4] inhibit the catalytic activity of bovine beta-trypsin and bovine alpha-chymotrypsin, which belong to MEROPS peptidase family S1 (InterPro: IPR001254).[5]

This group of proteins is now used in the creation of insecticides, vaccines, and protein engineering scaffolds.


The complete covalent structure of several such toxins has been deduced: They comprise around 66 amino acid residues forming a three stranded anti-parallel beta sheet over which lies an alpha helix of approximately three turns. Four disulfide bridges cross-link the structure of the long-chain toxins whereas the short toxins contain only three.[6][7] BmKAEP, an anti-epilepsy peptide isolated from the venom of the Manchurian scorpion,[8] shows similarity to both scorpion neurotoxins and anti-insect toxins.


The toxin's molecular function is to inhibit ion channels. Scorpion toxins are used in insecticides, vaccines, and protein engineering scaffolds. The toxins are now used to treat cancer patients by injecting fluorescent scorpion toxin into cancerous tissue to show tumor boundaries. Scorpion toxin genes are also used to kill insect pests by creating hypervirulent fungus in the insect through gene insertion.



  1. ^ PDB: 1PTX​; Housset D, Habersetzer-Rochat C, Astier JP, Fontecilla-Camps JC (April 1994). "Crystal structure of toxin II from the scorpion Androctonus australis Hector refined at 1.3 A resolution". J. Mol. Biol. 238 (1): 88–103. doi:10.1006/jmbi.1994.1270. PMID 8145259. 
  2. ^ Krezel, A. M.; Kasibhatla, C.; Hidalgo, P.; MacKinnon, R.; Wagner, G. (1995). "Solution structure of the potassium channel inhibitor agitoxin 2: Caliper for probing channel geometry". Protein Science 4 (8): 1478–1489. doi:10.1002/pro.5560040805. PMC 2143198. PMID 8520473. 
  3. ^ Ronchi S, Ceciliani F, Ascenzi P, Bortolotti F, Menegatti E, Palmieri S (1994). "Purification, inhibitory properties, amino acid sequence and identification of the reactive site of a new serine proteinase inhibitor from oil-rape (Brassica napus) seed". FEBS Lett. 342 (2): 221–224. doi:10.1016/0014-5793(94)80505-9. PMID 8143882. 
  4. ^ Bolognesi M, Ronchi S, Tedeschi G, Ascenzi P, Bortolotti F, Menegatti E, Palmieri S, Thomas RM (1992). "Purification, inhibitory properties and amino acid sequence of a new serine proteinase inhibitor from white mustard (Sinapis alba L.) seed". FEBS Lett. 301 (1): 10–14. doi:10.1016/0014-5793(92)80199-Q. PMID 1451776. 
  5. ^ Rawlings ND, Barrett AJ, Tolle DP (2004). "Evolutionary families of peptidase inhibitors". Biochem. J. 378 (Pt 3): 705–16. doi:10.1042/BJ20031825. PMC 1224039. PMID 14705960. 
  6. ^ Granier C, Kopeyan C, Rochat H, Mansuelle P, Sampieri F, Brando T, Bahraoui EM (1990). "Primary structure of scorpion anti-insect toxins isolated from the venom of Leiurus quinquestriatus quinquestriatus". FEBS Lett. 261 (2): 423–426. doi:10.1016/0014-5793(90)80607-K. PMID 2311768. 
  7. ^ Rochat H, Gregoire J (1983). "Covalent structure of toxins I and II from the scorpion Buthus occitanus tunetanus". Toxicon 21 (1): 153–162. doi:10.1016/0041-0101(83)90058-2. PMID 6845379. 
  8. ^ Zhou XH, Yang D, Zhang JH, Liu CM, Lei KJ (1989). "Purification and N-terminal partial sequence of anti-epilepsy peptide from venom of the scorpion Buthus martensii Karsch". Biochem. J. 257 (2): 509–517. doi:10.1042/bj2570509. PMC 1135608. PMID 2930463. 

External links

This article incorporates text from the public domain Pfam and InterPro IPR002061

This page is based on a Wikipedia article. The text is available under the Creative Commons Attribution/Share-Alike License.

This tab holds the annotation information that is stored in the Pfam database. As we move to using Wikipedia as our main source of annotation, the contents of this tab will be gradually replaced by the Wikipedia tab.

Scorpion short toxin Provide feedback

This family contains various secreted scorpion short toxins and seems to be unrelated to PF00451.

External database links

This tab holds annotation information from the InterPro database.

InterPro entry IPR007958

Short scorpion toxin chloride channel inhibitors are short-chain neurotoxins (SCNs), which block small-conductance chloride channels. They are 30-40-residue long and contain four intramolecular disulphide bridges, which have been assigned as C1-C4, C2-C6, C3-C7 and C5-C8 [PUBMED:7819188, PUBMED:9210487, PUBMED:10048185].

The global fold of the scorpion short toxin chloride channel inhibitor subfamily is an alpha-helix packed on a two-stranded beta-sheet. The structure also contains a short fragment in an extended form. The two antiparalllel beta-strands are connected by a type I beta-turn. The four disulphide bridges help to maintain a very compact structure by heavily attaching the N-terminal and C-terminal ends to the alpha-helix [PUBMED:7819188, PUBMED:9210487, PUBMED:10048185].

Gene Ontology

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Domain organisation

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Pfam Clan

This family is a member of clan Knottin_1 (CL0054), which has the following description:

This clan includes a number of toxin families that share the knottin structure. These families come from scorpions, plants and arthropods.

The clan contains the following 13 members:

BmKX Defensin_2 Defensin_like Gamma-thionin SCRL SLR1-BP Toxin_17 Toxin_2 Toxin_3 Toxin_37 Toxin_38 Toxin_5 Toxin_6


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Curation and family details

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Seed source: Pfam-B_7892 (release 7.7)
Previous IDs: toxin_5; Toxin_5; Toxin_5_;
Type: Domain
Author: Moxon SJ
Number in seed: 6
Number in full: 0
Average length of the domain: 0.00 aa
Average identity of full alignment: 0 %
Average coverage of the sequence by the domain: 0.00 %

HMM information View help on HMM parameters

HMM build commands:
build method: hmmbuild -o /dev/null HMM SEED
search method: hmmsearch -Z 11927849 -E 1000 --cpu 4 HMM pfamseq
Model details:
Parameter Sequence Domain
Gathering cut-off 25.0 25.0
Trusted cut-off 26.8 26.5
Noise cut-off 23.2 22.6
Model length: 32
Family (HMM) version: 10
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Species distribution

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For those sequences which have a structure in the Protein DataBank, we use the mapping between UniProt, PDB and Pfam coordinate systems from the PDBe group, to allow us to map Pfam domains onto UniProt sequences and three-dimensional protein structures. The table below shows the structures on which the Toxin_5 domain has been found. There are 2 instances of this domain found in the PDB. Note that there may be multiple copies of the domain in a single PDB structure, since many structures contain multiple copies of the same protein seqence.

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