PROSITE documentation PDOC60028 [for PROSITE entry PS60028]Scorpion calcine family signature
Toxins of the scorpion calcine family bind directly to ryanodine receptors (RyRs), intracellular channel targets of the endoplasmic reticulum, and induce long lasting channel openings in a mode of smaller conductance. They have the ability to translocate into cells by crossing the plasma membrane [1,2,3].
Toxins of scorpion calcine family are highly basic 33-amino acid peptides that present three disulfide bridges (C1-C4, C2-C5, and C3-C6) and fold along a knottin or inhibitor cystine knot motif (see <PDOC60004>) [1,2,3] [E1]. Their three dimensional structure consists of a compact disulfide-bonded core from which emerge loops and the N-terminus. The main element of regular secondary structure is a double-stranded antiparallel β-sheet. A third peripheral extended strand is almost perpendicular to the double-stranded antiparallel β-sheet [2,4]. Scorpion calcine mimic the activating segment of the dihydropyridine receptor II-III loop, which interacts with a region of the ryanodine receptor (see <PDB:1C6W>) [1,2,5].
This family includes:
- Imperatoxin-A (IpTx A) from Pandinus imperator (Emperor scorpion).
- Opicalcin-1 and -2 from Opistophthalmus carinatus (African yellow leg scorpion).
- Maurocalcin (MCa) from Scorpio maurus palmatus (Chactoid scorpion).
We have developed a pattern that contains six conserved cysteines with a C-C-CC-C-C cysteine arrangement.
Expert(s) to contact by email: Last update:February 2006 / First entry.
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PROSITE method (with tools and information) covered by this documentation:
1 | Authors | Gurrola G.B. Arevalo C. Sreekumar R. Lokuta A.J. Walker J.W. Valdivia H.H. |
Title | Activation of ryanodine receptors by imperatoxin A and a peptide segment of the II-III loop of the dihydropyridine receptor. | |
Source | J. Biol. Chem. 274:7879-7886(1999). | |
PubMed ID | 10075681 |
2 | Authors | Fajloun Z. Kharrat R. Chen L. Lecomte C. Di Luccio E. Bichet D. El Ayeb M. Rochat H. Allen P.D. Pessah I.N. De Waard M. Sabatier J.M. |
Title | Chemical synthesis and characterization of maurocalcine, a scorpion toxin that activates Ca(2+) release channel/ryanodine receptors. | |
Source | FEBS. Lett. 469:179-185(2000). | |
PubMed ID | 10713267 |
3 | Authors | Esteve E. Mabrouk K. Dupuis A. Smida-Rezgui S. Altafaj X. Grunwald D. Platel J.-C. Andreotti N. Marty I. Sabatier J.-M. Ronjat M. De Waard M. |
Title | Transduction of the scorpion toxin maurocalcine into cells. Evidence that the toxin crosses the plasma membrane. | |
Source | J. Biol. Chem. 280:12833-12839(2005). | |
PubMed ID | 15653689 | |
DOI | 10.1074/jbc.M412521200 |
4 | Authors | Mosbah A. Kharrat R. Fajloun Z. Renisio J.-G. Blanc E. Sabatier J.-M. El Ayeb M. Darbon H. |
Title | A new fold in the scorpion toxin family, associated with an activity on a ryanodine-sensitive calcium channel. | |
Source | Proteins 40:436-442(2000). | |
PubMed ID | 10861934 | |
DOI | 10.1002/1097-0134(20000815)40:3<436::AID-PROT90>3.0.CO;2-9 |
5 | Authors | Green D. Pace S. Curtis S.M. Sakowska M. Lamb G.D. Dulhunty A.F. Casarotto M.G. |
Title | The three-dimensional structural surface of two beta-sheet scorpion toxins mimics that of an alpha-helical dihydropyridine receptor segment. | |
Source | Biochem. J. 370:517-527(2003). | |
PubMed ID | 12429019 | |
DOI | 10.1042/BJ20021488 |
E1 | Title | https://bioserv.cbs.cnrs.fr |
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