Английская Википедия:Hemitoxin

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Hemitoxin (HTX; α-KTx6.15) is a 35-mer basic peptide from the venom of the Iranian scorpion Hemiscorpius lepturus, which reversibly blocks Kv1.1, Kv1.2 and Kv1.3 voltage-gated K+ channels.[1]

Sources

HTX is a neurotoxin derived from the venom of the scorpion Hemiscorpius lepturus, which is found in the southwest province of Iran, Khuzestan. Hemitoxin constitutes about 0.1% of all venom proteins found in the Hemiscorpius lepturus venom gland.[1]

Chemistry

HTX is a peptide composed of 35 amino acids including eight cysteine residues which are cross linked forming four intramolecular cystine amino acids via disulfide bridges. It belongs to subfamily 6 of the α-KTx family of potassium channel scorpion toxins and has the highest sequence similarity with Maurotoxin (MTX), which is derived from a Tunisian scorpion called Scorpio maurus palmatus. MTX is also a K+ channel blocker but is composed of 34 amino acids instead of 35.[1]

Target

HTX is a voltage-gated K+ channel blocker peptide. It reversibly blocks type Kv1.1, Kv1.2 and Kv1.3 channels with IC50 values of 13, 16 and 2 nM, respectively. HTX has a different affinity for K+ channels. It appears to be 20 times less potent on Kv1.2 channels and 90 times more potent on Kv1.3 channels than the α-KTx6 family member MTX.[1]

Mode of Action

HTX causes reversible current inhibition on Kv1.1, Kv1.2 and Kv1.3 channels.[1]

Toxicity

Intracerebroventricular injection of HTX has been shown to cause neurotoxic symptoms in mice with an LD50 of 0.3 μg per 20 g body weight.[1]

References

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