1c6w
From Proteopedia
MAUROCALCIN FROM SCORPIO MAURUS
Structural highlights
FunctionCAMAU_SCOPA This toxin stabilizes ryanodine receptor 1 (RyR1) opening in a long-lasting subconductance state (48%-60% of the full conductance state) (PubMed:10713267, PubMed:12869557, PubMed:27114612). Furthermore, it triggers calcium release from sarcoplasmic vesicles (6.6 nM are enough to induce a sharp release, and 60% of the total calcium is released after toxin (100 nM) addition) probably by acting as a cell-penetrating peptide (CPP) (PubMed:27114612). In addition, it has been shown to dose-dependently stimulate ryanodine binding to RyR1 (EC(50)=12.5-26.4 nM) (PubMed:12869557, PubMed:17291197, PubMed:17888395, PubMed:27114612). It also augments the bell-shaped calcium-[3H]ryanodine binding curve that is maximal at about 10 uM calcium concentration (PubMed:27114612). It binds a different site as ryanodine (PubMed:10713267). It acts synergistically with caffeine (By similarity). In vivo, intracerebroventricular injection into mice causes death (PubMed:10713267).[UniProtKB:A0A1L4BJ42][UniProtKB:B8QG00][UniProtKB:P59868][1] [2] [3] [4] [5] Publication Abstract from PubMedWe determined the structure in solution by (1)H two-dimensional NMR of Maurocalcine from the venom of Scorpio maurus. This toxin has been demonstrated to be a potent effector of ryanodyne-sensitive calcium channel from skeletal muscles. This is the first description of a scorpion toxin which folds following the Inhibitor Cystine Knot fold (ICK) already described for numerous toxic and inhibitory peptides, as well as for various protease inhibitors. Its three dimensional structure consists of a compact disulfide-bonded core from which emerge loops and the N-terminus. A double-stranded antiparallel beta-sheet comprises residues 20-23 and 30-33. A third extended strand (residues 9-11) is perpendicular to the beta-sheet. Maurocalcine structure mimics the activating segment of the dihydropyridine receptor II-III loop and is therefore potentially useful for dihydropyridine receptor/ryanodine receptor interaction studies. Proteins 2000;40:436-442. A new fold in the scorpion toxin family, associated with an activity on a ryanodine-sensitive calcium channel.,Mosbah A, Kharrat R, Fajloun Z, Renisio JG, Blanc E, Sabatier JM, El Ayeb M, Darbon H Proteins. 2000 Aug 15;40(3):436-42. PMID:10861934[6] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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Categories: Large Structures | Scorpio maurus | Ayeb M | Blanc E | Darbon H | Fajloun Z | Kharrat R | Mosbah A | Renisio J-G | Sabatier J-M