Compounds that bind the glucagon-like peptide 1 (GLP-1) receptor, methods of their synthesis, methods of their therapeutic and / or prophylactic use, and methods of their use in stabilizing GLP-1 receptor in vitro for crystallization of the GLP-1 receptor are provided. Certain compounds may have activity as modulators or potentiators with respect to glucagon receptor, GIP receptor, GLP-1 and GLP-2 receptors, and PTH receptor on their own or in the presence of receptor ligands such as GIP(1-42), PTH(1-34), Glucagon(1-29), GLP-2(1-33), GLP-1(7-36), GLP-1(9-36), oxyntomodulin and exendin variants.