A Molecular Recognition Code: Its Use for the Purification of ACTH, Endorphin, and LHRH Receptors

In recent years a great deal of emphasis has been placed on the isolation and characterization of receptors that are found on the surface of cells. An understanding of receptor-mediated biological responses would not be complete without an understanding of receptor structure and ligand-induced signal transmission. In an effort to dissect receptor structure and function, many investigators have used anti-receptor antibodies, the advantages of which are numerous (1). A problem with this experimental approach is that monospecific anti-receptor antibodies can be difficult to make by conventional methodologies. As demonstrated by other reports in this publication, antibodies directed against idiotopes on anti-ligand antibodies can be used as probes for receptor structure. Conceptually, it is possible to envision that the anti-idiotypic antibodies represent conformational homologues of the respective ligands and therefore have the ability to bind receptors in much the same way as does the ligand. Thus, the ability of the immune system to produce internal images has been exploited to generate anti-receptor antibodies. Recent investigations in our laboratory have been directed at defining a molecular recognition code that may help to explain the ability of the immune system to produce these internal images. These studies have also resulted in the production of antibodies to and subsequent characterization of receptors for corticotropin (ACTH), endorphin, and luteinizing hormone-releasing hormone (LHRH).