Long-chain three-finger neurotoxin (L-3FTx)

Long-chain three-finger neurotoxins (L-3FTxs) are a major class of potent polypeptides found in the venom of elapid snakes, including cobras, mambas, and kraits (Kini & Doley, 2010). These toxins are characterized by a structural motif consisting of three beta-sheet loops extending from a central core, stabilized by five conserved disulfide bonds (Barber et al., 2013). Their primary biological function is the high-affinity, competitive antagonism of muscle-type nicotinic acetylcholine receptors (nAChRs) at the postsynaptic membrane of the neuromuscular junction (UniProt, 2023). By blocking the binding of acetylcholine, L-3FTxs effectively halt neuromuscular transmission, leading to progressive muscle weakness, flaccid paralysis, and potentially fatal respiratory failure (WHO, 2021). In clinical practice, these toxins are the primary targets for neutralization by antivenoms, which consist of purified antibodies from immunized animals. Recent research is also focused on developing next-generation therapeutics, such as broadly neutralizing human monoclonal antibodies like 95Mat5, to improve the efficacy and safety of snakebite treatments (Khalek et al., 2024).

Other names

Type II alpha-neurotoxinLong-chain alpha-neurotoxinLong neurotoxinL-3FTX

Competitive antagonism of the muscle-type nicotinic acetylcholine receptor (nAChR) at the postsynaptic neuromuscular junction.