Binds with high affinity to muscular (alpha-1/CHRNA1) and neuronal (alpha-7/CHRNA7) nicotinic acetylcholine receptor (nAChR) and inhibits acetylcholine from binding to the receptor, thereby impairing neuromuscular and neuronal transmission. Expressed by the venom gland. Neurotoxin 4.7.3 differs from 4.9.3 only in that Trp-26 has undergone partial photooxidation. LD(50) is 0.9 mg/kg by intraperitoneal injection. Belongs to the snake three-finger toxin family. Long-chain subfamily. Type II alpha-neurotoxin sub-subfamily.