The NgR3 antibody targets the Nogo-66 Receptor Homolog 3 (NgR3), a glycosylphosphatidylinositol (GPI)-anchored protein belonging to the Nogo receptor family. Initially identified for its homology to NgR1 and NgR2. NgR3 shares structural features, including leucine-rich repeat (LRR) domains, but differs in ligand-binding specificity. Unlike NgR1. which binds inhibitory myelin-associated proteins (e.g., Nogo-A, MAG, OMgp) to restrict axonal growth in the central nervous system (CNS), NgR3 interacts with the C-terminal domain of the chondroitin sulfate proteoglycan FAM5C/BCAN, suggesting a role in modulating extracellular matrix signaling.
NgR3 is expressed in both the CNS and peripheral nervous system (PNS), with higher levels observed in the PNS. Its function remains less defined, though studies propose involvement in neural development, synaptic plasticity, and possibly regenerative responses. NgR3 antibodies, often developed as research tools, block receptor-ligand interactions to study these pathways. Preclinical studies explore their therapeutic potential in neurological disorders, such as spinal cord injury or multiple sclerosis, where overcoming axonal growth inhibition is critical. However, NgR3's distinct ligand profile and signaling mechanisms compared to other NgRs highlight the need for targeted antibody design. Current research focuses on clarifying its physiological roles and validating its relevance in disease models.