Please note: this site relies heavily on the use of javascript. Without a javascript-enabled browser, this site will not function correctly. Please enable javascript and reload the page, or switch to a different browser.
0  structures 0  species 0  interactions 0  sequences 0  architectures

Family: Toxin_5 (PF05294)

Summary: Scorpion short toxin

Pfam includes annotations and additional family information from a range of different sources. These sources can be accessed via the tabs below.

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

Scorpion toxin Edit Wikipedia article

Scorpion toxin-like domain
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]



  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

The mapping between Pfam and Gene Ontology is provided by InterPro. If you use this data please cite InterPro.

Domain organisation

Below is a listing of the unique domain organisations or architectures in which this domain is found. More...

Loading domain graphics...

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


We store a range of different sequence alignments for families. As well as the seed alignment from which the family is built, we provide the full alignment, generated by searching the sequence database (reference proteomes) using the family HMM. We also generate alignments using four representative proteomes (RP) sets and the UniProtKB sequence database. More...

View options

We make a range of alignments for each Pfam-A family. You can see a description of each above. You can view these alignments in various ways but please note that some types of alignment are never generated while others may not be available for all families, most commonly because the alignments are too large to handle.

Representative proteomes UniProt
Jalview View            View 
HTML View             
PP/heatmap 1            

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

Key: ✓ available, x not generated, not available.

Format an alignment

Representative proteomes UniProt

Download options

We make all of our alignments available in Stockholm format. You can download them here as raw, plain text files or as gzip-compressed files.

Representative proteomes UniProt
Raw Stockholm Download             Download  
Gzipped Download             Download  

You can also download a FASTA format file containing the full-length sequences for all sequences in the full alignment.

HMM logo

HMM logos is one way of visualising profile HMMs. Logos provide a quick overview of the properties of an HMM in a graphical form. You can see a more detailed description of HMM logos and find out how you can interpret them here. More...


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.

Note: You can also download the data file for the tree.

Curation and family details

This section shows the detailed information about the Pfam family. You can see the definitions of many of the terms in this section in the glossary and a fuller explanation of the scoring system that we use in the scores section of the help pages.

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

Sunburst controls


Weight segments by...

Change the size of the sunburst


Colour assignments

Archea Archea Eukaryota Eukaryota
Bacteria Bacteria Other sequences Other sequences
Viruses Viruses Unclassified Unclassified
Viroids Viroids Unclassified sequence Unclassified sequence


Align selected sequences to HMM

Generate a FASTA-format file

Clear selection

This visualisation provides a simple graphical representation of the distribution of this family across species. You can find the original interactive tree in the adjacent tab. More...

Loading sunburst data...

Tree controls


The tree shows the occurrence of this domain across different species. More...


Please note: for large trees this can take some time. While the tree is loading, you can safely switch away from this tab but if you browse away from the family page entirely, the tree will not be loaded.

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;