the present invention relates to novel mammalian dna - r proteins and genes that encode such proteins . the invention is directed toward the isolation and characterization of mammalian dna - r proteins . the invention specifically provides isolated complementary dna copies of mrna corresponding to rat and human homologues of a mammalian dna - r gene . also provided are recombinant expression constructs capable of expressing the mammalian dna - r genes of the invention in cultures of transformed prokaryotic and eukaryotic cells , as well as such cultures of transformed cells that synthesize the mammalian catecholamine receptor proteins encoded therein . the invention also provides methods for screening compounds in vitro that are capable of binding to the mammalian dna - r proteins of the invention , and further characterizing the binding properties of such compounds in comparison with known dna - r agonists and antagonists . improved methods of pharmacological screening are provided thereby .