– Nogo-66 Receptor-Related Protein 3 (NgR3) has primary structures with NgR2 (NgRH1, NgRL3) and biochemical properties that are homologous to Nogo-66 receptor (NgR), and constitute a novel neuronal receptor protein family. NgR is GPI-anchored and contains eight leucine-rich repeats (LRR), it is the neuronal receptor for the myelin- associated proteins Nogo-A, OMgp (oligodendrocyte myelin glycoprotein), and MAG (myelin-associated glycoprotein) and mediates the inhibition of CNS axonal regeneration both in vitro and in vivo. NgR2 and NgR3 have similar structure and distinct but overlapping expression versus NgR. NgR2 can be metalloproteinase-cleaved to release a soluble ectodomain. NgR2 has also been shown to bind MAG, but ligands for NgR3 have not yet been determined. Mature huaman NgR3 shares 88%, 88%, 48% and 44% amino acid identity with mature mouse NgR3, rat NgR3, human NgRH1 and NgR, repectively.