Das Protein muss in hohen Anteilen in der Nahrung vorkommen, es muss im Magen-Darm-Trakt relativ lange stabil bleiben, damit zumindest einige Bereiche intakt durch die Darmschleimhaut in den Blutkreislauf gelangen, und es muss Bestandteile haben, welche die Produktion von speziellen Antikörpern, den IgE-Antikörpern, auslösen.

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Specific regions of proteins are called epitopes. Epitopes can comprise 5 or more consecutive amino acids or several amino acids that are not necessarily close together on the polypeptide chain but form a particular structure in the 3-dimensional protein molecule. Monospecific antibodies (as in monoclonal antibodies) recognize a single, unique epitope of a protein. For native proteins, antibodies usually recognize epitopes of proteins that are exposed or accessible. Monospecific antibodies can recognize proteins that have identical or similar epitopes (e.g., receptor proteins, ABC transporters). There is more information in the Internet under "antigenic epitope".