ABSTRACT
The peripheral nervous system (PNS) is designed to receive inputs from the environment and transduce these into signals that are sent to the central nervous system (CNS). While most PNS neurons carry some receptors for classical neurotransmitters like glutamate, they are only weakly sensitive to these substances (or are not nearly as sensitive to them as CNS neurons are). Instead, as their primary function is to detect changes in external cues-for instance, heat and foreign chemicals-they are thought to be activated mostly through a broad range of receptors that recognize such environmental signals. These receptors can be divided into several broad groups. The groups comprising the olfactory and taste receptors represent the classic examples of families that, taken together, can detect an extraordinary range of substances from the environment. Both groups are members of the GPCR superfamily and are coupled to various G-proteins, through which they transduce their signals in
12.1 Introduction ................................................................................................. 213 12.2 Discovery of the Mrgprs .............................................................................. 214 12.3 Expression of Mrgprs .................................................................................. 217 12.4 Generation of Mrgpr Knockout Animals .................................................... 219 12.5 Role of Mrgprs in Itch in Mice .................................................................... 219 12.6 Mrgpr Signaling Pathways ..........................................................................224 12.7 BAM8-22, an Mrgpr Agonist, Induces Itch in Humans ..............................225 12.8 Differences between Itch Receptors and Olfactory Receptors....................226 12.9 Other Mrgprs ............................................................................................... 227
12.9.1 MrgprD ........................................................................................... 227 12.9.2 MrgprA9 .........................................................................................228 12.9.3 MrgprE and MrgprF .......................................................................228 12.9.4 MrgprX2 ......................................................................................... 229
12.10 Dimerization ................................................................................................ 229 12.11 Questions .....................................................................................................230
