Once you isolate the cDNA for the receptor involved in mediating heart contraction, you sub-clone the receptor cDNA into an expression plasmids and then stably transfect COS cells and select the receptor-expressing COS-45 cell line. Using your receptor-expressing COS-45 cells, how would you demonstrate experimentally that the selective antagonist binds the receptor specifically? Describe the experiment you would perform and also the controls you would include.