Immunoprecipitation of Receptors

Antibodies have been widely used in biochemistry as selective probes to study the structure and function of important biological macromolecules. The usefulness of antibody molecules as research tools lies in their unique structure. Antibody molecules consist of two distinct domains; the Fab or “business” end of the molecule, which binds to the respective antigen with its exquisite specificity and the Fc region, which can be readily labeled with a wide range of tags. Prior to the advent of monoclonal antibody technology and the availability of protein primary structures via cDNA cloning, the generation of an antibody against a particular protein required the laborious prerequisite task of antigen purification to homogeneity followed by polyclonal antibody production. Neurotransmrtter receptors are, however, expressed at very low concentrations in mammalian brain, i.e., fmol-pmol receptors/ mg protein, and it was difficult to purify sufficient material for the generation of useful antibodies. However, the recent availability of neurotransmitter receptor cDNAs has revolutionized the generation of antireceptor antibodies worldwide in both academic and commercial laboratories. Receptor cDNAs can be readily manipulated to generate large amounts of protein or parts of the protein of interest, which can then be purified for antigen production. In addition, using the primary structure deduced from the respective cDNA sequences, synthetic oligopeptides can be used as immunogens to generate amino acid sequence-directed antireceptor antibodies.