action It is thought that heteroscodratoxin-1 modifies gating of specific potassium channels by shifting the activation threshold to more positive values. As a result larger depolarizations are needed to open channels. The mechanism underlying this modification has been largely elucidated using molecular docking simulation for the KV2.1 potassium channel which is highly expressed in mammalian neurons and interacts strongly with heteroscodratoxin-1. In this model the C-terminal residue of the KV2.1 S3-segment (S3C) serves as a binding site for Hmtx-1 forming both hydrophobic and hydrophilic bonds. Interaction between the toxin and the potassium channel induces a helical movement of S3C resulting in limited spatial freedom of the S4-segment which is responsible for channel gating. Toxicity Information on toxic effects of Heteroscodratoxin-1 in humans is not available. In mice, however, it has been found that intracerebroventricular injection of 500 pmol HmTx1 induces convulsions, spasms, tremors and death within 1 hour. At 100 pmol, a less severe response develops, although death still occurs after 2 hours. References External links Heteroscodratoxin-1 from the Uniprot website Toxin card for Heteroscodratoxin-1 from the Toxin, Toxin-target database website Ion channel toxins Neurotoxins Spider toxins