Abstract: The present invention provides compositions containing a common ligand linked to a detectable moiety and provides methods for the preparation of such compositions. The present invention also provides methods for screening candidate ligands for binding to a NAD binding receptor, which include contacting a receptor with a candidate ligand and a composition of the invention followed by evaluation of receptor binding. The screening method of the present invention has broad applicability and can be used to screen large numbers of a wide variety of ligands. The present invention further provides methods for detecting the binding activity of a putative receptor, which include combining the putative receptor with a composition of the invention and evaluating the level of detectable moiety. The invention also provides kits useful for detection of receptors having NAD binding activity and for screening of candidate ligands that bind to a NAD binding receptor.