Figure 58. The prolines are coloured dark blue. You see a proline in 4 of the 5 turns. Only the one on the top not. But that one has a Phe and an Arg, and those are very typical bind-and-(de-)activate-that-receptor residues. So, its a gamble, but I think that the Arg in the turn on the top is the 'active site' of this molecule.

Further, if the students look up the structure of acetylcholine, they see that it contains a branched positive charge. It doesn't require a big thinking step that an Arg can take the place of that part of the acetylcholine.

We cannot raise useful antibodies against erabutoxin, because by the time the immune system realizes it has work to do, we would be long dead.

It would be nice if the students looked up which animal produces this venom; how lethal is it (hard to find with Google), where does the animal live, etc.