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Calcicludine (CaC) is a protein toxin from the venom of the green mamba that inhibits high-voltage-activated calcium channels, especially L-type calcium channels.



Calcicludine is a toxin in the venom of the green mamba (Dendroaspis angusticeps).


Calcicludine is a 60-amino acid polypeptide with six cysteines forming three disulfide bridges. Calcicludine structurally resembles dendrotoxin, but works differently, since even at high concentrations, calcicludine has no effect on dendrotoxin-sensitive potassium channels in chicken and rat neurons.[1]


Calcicludine is a blocker of high-voltage-activated calcium channels (L-, N- and P-type channels). It has highest affinity to the L-type calcium channel (IC50 = 88nM[2]). However, sensitivity of the drug on the channel depends on the species and the tissue. For example, the IC50 for block of L-type calcium channels on a cerebellar granule cell is 0.2 nM, but the IC50 of the block of rat peripheral DRG neuronal L-type channels is around 60-80 nM.[1]

Mode of Action

Calcicludine has a unique mode of action, which is still incompletely understood. It has been suggested to act by a partial pore block or an effect on channel gating.[2]


Calcicludine has been shown to work on rat cardiac cells and rat cerebellum granule cells.[1]


[1]: Calcicludine, A Venom Peptide of the Kunitz-Type Protease Inhibitor Family, is a Potent Blocker of High-Threshold Ca 2+ Channels with a High Affinity for L-Type Channels in Cerebellar Granule Neurons, Schweitz et al., 1994
[2]: Block of Voltage-dependent Calcium Channel by the Green Mamba Toxin Calcicludine, Stotz et al., 1999

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