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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 toxin-like domain
Identifiers
SymbolToxin_3
PfamPF00537
InterProIPR002061
SCOP22sn3 / SCOPe / SUPFAM
OPM superfamily61
OPM protein1djt

Scorpion toxins are proteins, which may be mammal or insect specific, bind to sodium channels, inhibiting the inactivation of activated channels and blocking neuronal transmission. The complete covalent structure of the toxins has been deduced: it comprises around 66 amino acid residues and is cross- linked by 4 disulphide bridges[1][2]. An anti-epilepsy peptide isolated from scorpion venom[3] shows similarity to both scorpion neurotoxins and anti-insect toxins.

This family also contains a group of proteinase inhibitors from Arabidopsis thaliana and Brassica spp., which belong to MEROPS inhibitor family I18, clan I-. The Brassica napus (Oil seed rape) and Sinapis alba (White mustard) inhibitors[4][5], inhibit the catalytic activity of bovine beta-trypsin and bovine alpha-chymotrypsin, which belong to MEROPS peptidase family S1 (InterPro: IPR001254)[6].

This family contains both neurotoxins and plant defensins. The mustard trypsin inhibitor, MTI-2, is plant defensin. It is a potent inhibitor of trypsin with no activity towards chymotrypsin. MTI-2 is toxic for Lepidopteran insects, but has low activity against aphids. Brazzein is plant defensin-like protein. It is pH-stable, heat-stable and intensely sweet protein [7]

Subfamilies

References

  1. ^ 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. PMID 2311768.{{cite journal}}: CS1 maint: multiple names: authors list (link)
  2. ^ Rochat H, Gregoire J (1983). "Covalent structure of toxins I and II from the scorpion Buthus occitanus tunetanus". Toxicon. 21 (1): 153–162. PMID 6845379.
  3. ^ 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. PMID 2930463.{{cite journal}}: CS1 maint: multiple names: authors list (link)
  4. ^ 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. PMID 8143882.{{cite journal}}: CS1 maint: multiple names: authors list (link)
  5. ^ 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): 10-1 4. PMID 1451776. {{cite journal}}: line feed character in |pages= at position 5 (help)CS1 maint: multiple names: authors list (link)
  6. ^ Rawlings ND, Barrett AJ, Tolle DP (2004). "Evolutionary families of peptidase inhibitors". Biochem. J. 378: -. PMID 14705960.{{cite journal}}: CS1 maint: multiple names: authors list (link)
  7. ^ Sweetness determinant sites of brazzein, a small, heat-stable, sweet-tasting protein. Assa di-Porter FM, Aceti DJ, Markley JL; Arch Biochem Biophys 2000;376:259-265. PMID 10775411
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 15 members:

BmKX Defensin_2 Defensin_5 Defensin_like Gamma-thionin Macin SCRL SLR1-BP Toxin_17 Toxin_2 Toxin_3 Toxin_37 Toxin_38 Toxin_5 Toxin_6

Alignments

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  Seed
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RP55
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RP75
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1Cannot generate PP/Heatmap alignments for seeds; no PP data available

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  Seed
(6)
Full
(0)
Representative proteomes UniProt
(40)
RP15
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RP35
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RP55
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RP75
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  Seed
(6)
Full
(0)
Representative proteomes UniProt
(40)
RP15
(0)
RP35
(0)
RP55
(0)
RP75
(0)
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HMM logo

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Trees

This page displays the phylogenetic tree for this family's seed alignment. We use FastTree to calculate neighbour join trees with a local bootstrap based on 100 resamples (shown next to the tree nodes). FastTree calculates approximately-maximum-likelihood phylogenetic trees from our seed alignment.

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Curation and family details

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Curation View help on the curation process

Seed source: Pfam-B_7892 (release 7.7)
Previous IDs: toxin_5; Toxin_5; Toxin_5_;
Type: Domain
Sequence Ontology: SO:0000417
Author: Moxon SJ
Number in seed: 6
Number in full: 0
Average length of the domain: 0 aa
Average identity of full alignment: 0 %
Average coverage of the sequence by the domain: 0 %

HMM information View help on HMM parameters

HMM build commands:
build method: hmmbuild -o /dev/null HMM SEED
search method: hmmsearch -Z 61295632 -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: 16
Download: download the raw HMM for this family

Species distribution

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trRosetta Structure

The structural model below was generated by the Baker group with the trRosetta software using the Pfam UniProt multiple sequence alignment.

The InterPro website shows the contact map for the Pfam SEED alignment. Hovering or clicking on a contact position will highlight its connection to other residues in the alignment, as well as on the 3D structure.

Improved protein structure prediction using predicted inter-residue orientations. Jianyi Yang, Ivan Anishchenko, Hahnbeom Park, Zhenling Peng, Sergey Ovchinnikov, David Baker Proceedings of the National Academy of Sciences Jan 2020, 117 (3) 1496-1503; DOI: 10.1073/pnas.1914677117;