Nyctalopin (NYX)

Nyctalopin is a small leucine-rich repeat proteoglycan that is tethered to the retinal cell surface via a glycosylphosphatidylinositol (GPI) anchor in humans. It is primarily expressed in the retina, where it plays a critical role as a scaffold at the photoreceptor-to-ON bipolar cell synapse, positioning key signaling molecules such as the TRPM1 cation channel and the mGluR6 receptor for rapid and reliable synaptic transmission. Its structure consists of 11 LRR domains flanked by cysteine-rich regions. Nyctalopin's extracellular LRR domain enables important protein–protein interactions required for synaptic localization of TRPM1. Mutations in the NYX gene disrupt nyctalopin’s structural integrity and localization, directly causing X-linked congenital stationary night blindness (CSNB1), a non-progressive disorder characterized by impaired retinal ON-pathway signaling and resulting in night blindness. There are no current therapies that directly target nyctalopin; diagnosis and carrier screening are performed genetically. Nyctalopin is not involved in cancer, inflammation, neurodegeneration, or infection; its disease relevance is specific to inherited retinal disorders.

Other names

NYXCLRPCSNB1ACSNB1CSNB4NBM1leucine-rich repeat proteinsmall leucine-rich proteoglycannyctalopin