Transfect a host cell culture like CHO or HEK with the desired receptor, force over expression of the cell receptor and separate the cells and test the lead in a dilution series against a reference agonist or antagonist using either binding or functional assay. which will give you the interaction with the receptor.
repeat for every receptor you want to screen. sometimes multiple receptor assays can be carried out in one cell line but not usually which is why screening 100 leads against 10 receptors is usually much much cheaper than screening 10 leads against 100 receptors
