We just learned about the Paratope.
Another part of the immune system is an Epitope.
Just like we learned that the paratope is part of the antibody that is like the lock, the epitope is the part of the antigen that is like the key.
The antibody lock goes around looking for an antigen key to match.
So the paratopes look for epitopes to match.
(from: wikipedia - epitope)
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