Binds with high affinity to muscle nicotinic acetylcholine receptor (nAChR) and inhibit acetylcholine from binding to the receptor, thereby impairing neuromuscular transmission. Compete with the binding of alpha-bungarotoxin on muscle AChR (from Torpedo) with an IC(50) of 0.31 uM (SNTX1) and 3.1 uM (SNTX5). Is able of exerting muscle paralysis, spasms and increased respiration. Expressed by the venom gland. LD(50) is 1 mg/kg by intravenous injection into mice. Belongs to the snake three-finger toxin family. Short-chain subfamily. Type III alpha-neurotoxin sub-subfamily.