Cobra (Naja sp.) venom action. Molecular model showing the structure of an alpha-cobratoxin (snake venom protein) bound to an acetylcholine binding protein (AChBP) from another animal. The acetylcholine binding protein (circular) is part of the acetylcholine receptor, which is an essential link between the brain and the muscles. The venom (five outer structures) acts by blocking this region of the acetylcholine receptor, causing paralysis.