NgR3/NgRH2 (also known as reticulon-4 receptor-Like 1), along with the related NgR1 and NgR2, is a member of the Nogo66 receptor (NgR) family. NgR proteins are expressed primarily by neurons in the central and peripheral mammalian nervous system. NgR proteins play an essential role in mediating axon growth inhibition induced by the structurally distinct proteins Nogo, myelin associated glycoprotein (MAG), and myelin oligodendrocyte glycoprotein (OMgp) (1, 2).These proteins belong to the family of myelin-associated inhibitors (MAIs). NgR proteins are composed of 8 leucine-rich repeats (LRRs) flanked by N-terminal and C-terminal leucine-rich capping domains and are attached at the cell surface by a C-terminal glycosylphosphatidylinositol (GPI) anchor (3). Because NgR proteins have no transmembrane domain, they must be associated with membrane proteins in order to transduce cell signaling (2).  Both NGF R/TNFRSF16 (p75) and TROY/TNFRSF19 have been identified as NgR1-associated components (4, 5). Mouse NgR3 shares 88% and 96% amino acid sequence identity with human and rat NgR3 respectively. NgR1 and NgR3 serve as receptors for chondroitin sulfate proteoglycans (CSPGs) (6). CSPGs and MAIs are known to stabilize neuronal structure and influence the growth and guidance of developing neurons (7). Therefore, NgR proteins are part of a multicomponent receptor system implicated in pathways that limit neuronal growth and increase the structural stability of synapses.