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 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. Calcicludine is a blocker of high-voltage-activated calcium channels (L-, N- and P-type channels). However, sensitivity of the drug on the channel depends on the species and the tissue. 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. Calcicludine has been shown to work on rat cardiac cells and rat cerebellum granule cells.
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