A large family of G-protein-coupled receptors, with sequence homology to the oncoprotein MAS1, has been shown to be specifically expressed in nociceptive sensory neurons. Significance and context Vertebrate peripheral chemosensory neurons express large families of G-protein-coupled receptors (GPCRs), reflecting the diversity of ligands that these sensory systems detect. In contrast, peripheral somatosensory neurons within the body are thought not to discriminate specifically between different

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... emical ligands, but rather to respond to polymodal stimuli using broadly tuned receptors such as the vanilloid receptor I (VRI). Dorsal root ganglia (DRGs) contain diverse subpopulations of primary sensory neurons. One category comprises the nociceptors, which respond to a variety of noxious thermal, mechanical and chemical stimuli that cause acute pain. These receptors also mediate the chronic pain associated with inflammatory responses or nerve injury (neuropathic pain). Dong et al. describe a gene family consisting of nearly 50 MAS1-related GPCR genes -Mas-related genes (mrgs)whose expression indicates an unanticipated degree of molecular diversity among DRG sensory neurons.