Purification and characterization of chlorotoxin, a chloride channel ligand from the venom of the scorpion

DeBin, John A.; Maggio, John E.; Strichartz, Gary R.

doi:10.1152/ajpcell.1993.264.2.c361

Cited by 371 publications

(294 citation statements)

References 24 publications

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“…Thus, the mechanisms by which NPPB and Cltx inhibit Transwell migration differ because NPPB inhibits the function of ClC-3 channes, whereas Cltx depletes functional ClC-3 channels from the membrane. These data indicate a novel action of this scorpion toxin, which was presumed to be a Cl − -channel-specific peptide (DeBin et al, 1993). Rather than acting directly on the ion channel, it appears to interfere with protein trafficking.…”

Section: A Putative CL − Channel Inhibitor (Cltx) Is Currently In Climentioning

confidence: 89%

“…Before the molecular characterization of glioma Cl − channels, which we now presume to be primarily ClC-3 channels, we found that Cltx, a scorpion-derived 36-residue peptide that was isolated as a putative Cl − -channel blocker (DeBin et al, 1993) inhibits whole-cell Cl − currents in glioma cells in vitro (Lippiat et al, 1998) and in situ (Ullrich et al, 1998). Moreover, Cltx inhibits glioma-cell invasion in several in situ invasion models, as does the Cl − -channel inhibitor NPPB (Soroceanu et al, 1999).…”

Section: A Putative CL − Channel Inhibitor (Cltx) Is Currently In Climentioning

confidence: 99%

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A role for ion channels in glioma cell invasion

McFerrin¹,

2005

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Many cells, including neuronal and glial progenitor cells, stem cells and microglial cells, have the capacity to move through the extracellular spaces of the developing and mature brain. This is particularly pronounced in astrocyte-derived tumors, gliomas, which diffusely infiltrate the normal brain. Although a significant body of literature exists regarding signals that are involved in the guidance of cells and their processes, little attention has been paid to cell-shape and cell-volume changes of migratory cells. However, extracellular spaces in the brain are very narrow and represent a major obstacle that requires cells to dynamically regulate their volume. Recent studies in glioma cells show that this involves the secretion of Cl − and K + with water. Pharmacological inhibition of Cl − channels impairs their ability to migrate and limits tumor progression in experimental tumor models. One Cl − -channel inhibitor, chlorotoxin, is currently in Phase II clinical trials to treat malignant glioma. This article reviews our current knowledge of cell-volume changes and the role of ion channels during the migration of glioma cells. It also discusses evidence that supports the importance of channel-mediated cell-volume changes in the migration of immature neurons and progenitor cells during development. New unpublished data is presented, which demonstrates that Cl − and K + channels involved in cell shrinkage localize to lipid-raft domains on the invadipodia of glioma cells and that their presence might be regulated by trafficking of these proteins in and out of lipid rafts.

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Section: A Putative CL − Channel Inhibitor (Cltx) Is Currently In Climentioning

confidence: 89%

Section: A Putative CL − Channel Inhibitor (Cltx) Is Currently In Climentioning

confidence: 99%

A role for ion channels in glioma cell invasion

McFerrin¹,

2005

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“…Imperatoxin I is a heterodimer (104 and 27 amino acids, respectively) that blocks Ca 2ϩ channel by inhibition of ryanodine binding (9). Scorpion toxins that inhibit Cl Ϫ channels are ϳ36 amino acids long with four disulfide bridges (10,11). Scorpion toxins possess a highly conserved secondary structure arrangement comprising double-or triplestranded antiparallel ␤-sheet and a stretch of ␣-helix maintained by a couple of disulfide bridges (4,12).…”

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confidence: 99%

κ-Hefutoxin1, a Novel Toxin from the ScorpionHeterometrus fulvipes with Unique Structure and Function

Srinivasan¹,

Vaithiyalingam²,

Huys³

et al. 2002

Journal of Biological Chemistry

131

112

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An important and exciting challenge in the postgenomic era is to understand the functions of newly discovered proteins based on their structures. The main thrust is to find the common structural motifs that contribute to specific functions. Using this premise, here we report the purification, solution NMR, and functional characterization of a novel class of weak potassium channel toxins from the venom of the scorpion Heterometrus fulvipes. These toxins, -hefutoxin1 and -hefutoxin2, exhibit no homology to any known toxins. NMR studies indicate that -hefutoxin1 adopts a unique three-dimensional fold of two parallel helices linked by two disulfide bridges without any ␤؊sheets. Based on the presence of the functional diad (Tyr 5 /Lys 19 ) at a distance (6.0 ؎ 1.0 Å) comparable with other potassium channel toxins, we hypothesized its function as a potassium channel toxin. -Hefutoxin 1 not only blocks the voltage-gated K ؉ -channels, Kv1.3 and Kv1.2, but also slows the activation kinetics of Kv1.3 currents, a novel feature of -hefutoxin 1, unlike other scorpion toxins, which are considered solely pore blockers. Alanine mutants (Y5A, K19A, and Y5A/K19A) failed to block the channels, indicating the importance of the functional diad.

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“…For instance, snake venoms contain potent neurotoxins that block acetylcholine receptors (3), and snail and spider venoms contain small molecular weight proteins directed against neuronal Ca 2ϩ channels (4,5). A Cl Ϫ channel-specific blocker peptide was also recently isolated from a scorpion venom (6). Thus, there exist a vast array of natural ligands useful for structural and functional characterization of ionic channels.…”

mentioning

confidence: 99%

The Mechanism of Inhibition of Ryanodine Receptor Channels by Imperatoxin I, a Heterodimeric Protein from the Scorpion Pandinus imperator

Zamudio

Condé

Arévalo

et al. 1997

Journal of Biological Chemistry

103

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We present an in-depth analysis of the structural and functional properties of Imperatoxin I (IpTx i ), an ϳ15-kDa protein from the venom of the scorpion Pandinus imperator that inhibits Ca 2؉ release channel/ryanodine receptor (RyR) activity (Valdivia, H. H., Kirby, M. S., Lederer, W. J., and Coronado, R. (1992) Proc. Natl. Acad. Sci. U.S.A. 89, 12185-12189). A cDNA library was prepared from the venomous glands of this scorpion and used to clone the gene encoding IpTx i . From a single continuous messenger RNA, the information coding for the toxin is translated into two mature polypeptide subunits after elimination of a basic pentapeptide. The IpTx i dimer consists of a large subunit (104-amino acid residues) with phospholipase A 2 (PLA 2 ) activity covalently linked by a disulfide bond to a smaller (27 amino acid residues), structurally unrelated subunit. Thus, IpTx i is a heterodimeric protein with lipolytic action, a property that is only shared with ␤-bungarotoxins, a group of neurotoxins from snake venoms. The enzymatic subunit of IpTx i is highly homologous to PLA 2 from bee (Apis mellifera) and lizard (Heloderma horridum) venoms. The small subunit has no significant similarity to any other known peptide, including members of the Kunitz protease inhibitors superfamily that target the lipolytic effect of ␤-bungarotoxins. A synthetic peptide with amino acid sequence identical to that of the small subunit failed to inhibit RyR. On the other hand, treatment of IpTx i with p-bromophenacylbromide, a specific inhibitor of PLA 2 activity, greatly reduced the capacity of IpTx i to inhibit RyRs. These results suggested that a lipid product of PLA 2 activity, more than a direct IpTx i -RyR interaction, was responsible for RyR inhibition.

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Purification and characterization of chlorotoxin, a chloride channel ligand from the venom of the scorpion

Cited by 371 publications

References 24 publications

A role for ion channels in glioma cell invasion

A role for ion channels in glioma cell invasion

κ-Hefutoxin1, a Novel Toxin from the ScorpionHeterometrus fulvipes with Unique Structure and Function

The Mechanism of Inhibition of Ryanodine Receptor Channels by Imperatoxin I, a Heterodimeric Protein from the Scorpion Pandinus imperator

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