BRAINCAKECobra Venom
Cobra venom contains toxins that act on the nervous system. The best known is α-cobratoxin, a protein that acts at neuromuscular junctions, the synapses between motor neurones and skeletal muscle fibres.
At a normal neuromuscular junction, acetylcholine (ACh) released from the motor neurone binds to nicotinic acetylcholine receptors on the muscle fibre membrane. Their sodium ion channels open, the muscle membrane depolarises and the muscle fibre contracts.
α-cobratoxin binds very tightly, almost irreversibly, to the nicotinic ACh receptors. It is an antagonist:
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Key terms in this lesson
- agonist
- A drug or molecule that binds to a receptor and activates it, mimicking the natural ligand.
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