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Scorpion toxin

Scorpion long-chain toxin
Identifiers
Symbol	Toxin_3
Pfam	PF00537
InterPro	IPR002061
SCOP	2sn3
OPM family	61
OPM protein	1djt
Available PDB structures: 1lqi :21-74 1lqh :21-74 1lqq :2-55 1omyA:21-74 1t7bA:21-74 1djtA:21-74 1sn1A:21-74 1t7eA:21-74 1t7aA:21-74 1chzA:2-55 1sn4A:16-69 1snb :2-55 1kv0B:2-55 1aho :21-74 1segA:21-74 1ptx :21-74 1fh3A:2-56 1bmr :2-56 1nrb :2-52 1nra :2-52 1t1tA:3-53 2a7tA:2-55 1cn2 :17-71 1vna :20-74 1vnb :20-74 1jzaA:20-74 1jzbA:20-74 2sn3 :20-74 2b3cA:20-73 1b3cA:20-73 1pe4A:1-54 1npiA:21-71 1b7dA:21-71 1bcg :20-74 1t0zA:20-69 1wwnA:20-69 1i6gA:1-49 1i6fA:1-49 1nh5A:1-49 1jxcA:28-88

Scorpion short-chain toxin
Identifiers
Symbol	Toxin_5
Pfam	PF05294
InterPro	IPR007958
SCOP	1chl
OPM protein	1sis
Available PDB structures: 1chl :2-35 1sis :2-33

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.

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

Neurotoxin IPR001219

References

^ 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.
^ 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.
^ 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.
^ 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.
^ 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.
^ Rawlings ND, Barrett AJ, Tolle DP (2004). "Evolutionary families of peptidase inhibitors". Biochem. J. 378: -. PMID 14705960.
^ 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. PubMed

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

Categories: Protein domains | Peripheral membrane proteins

This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia article "Scorpion_toxin". A list of authors is available in Wikipedia.