The Mas-related genes (Mrgs), also known as sensory neuron-specific G-protein coupled receptors (SNSRs), are selectively expressed in subpopulations of sensory neurons involved in the perceptor of pain (Dong et al., 2001). The Mrg family in rodents consists of 50 receptors in the MrgA-MrgH subfamilies, but humans contain fewer Mrg members. MrgD (also known as TGR7) is found across species from rodents to humans, and its expression is restricted to nonpeptidergic, small-diameter, IB4+ dorsal root ganglion (DRG) neurons. MrgD binds β-alanine, but not L-alanine, which results in increased intracellular calcium and the suppression of forskolin-induced cAMP production, thus suggesting coupling to Gq and Gi proteins (Shinohara et al., 2004). β-alanine-induced activation of MrgD inhibits KCNQ2/3-mediated M-currents in cells overexpressing MrgD and KCNQ2/3 and also in cultured DRG neurons, which indicates that MrgD enhances nociceptive signaling (Crozier et al., 2007). Millipore's MrgD membrane preparations are crude membrane preparations made from our proprietary stable recombinant cell lines to ensure high-level of GPCR surface expression; thus, they are ideal HTS tools for screening of MrgD interactions with its ligands. The cell line exhibits a calcium response with EC50s of 11 µM for β-alanine. The membrane preparations exhibit EC50s of 69 µM for β-alanine in a GTPS binding assay.