How to find reliable supplier for GPCR screening?

Question

GPCRs are expressed throughout the body and modulate a wide array of essential physiological processes, including regulating the senses of vision, taste, and olfaction, as well as mediating cellular responses to hormones and neurotransmitters. GPCR signal transduction is accomplished by the binding of a receptor agonist to an exposed extracellular or intra-membrane site on the receptor, which induces a conformational change in the receptor protein.