Neurexophilin-1 or NXPH1 is a secreted glycoprotein, which belongs to the Neurexophilin family. The Neurexophilin family contains at least four genes and resembles a neuropeptide, suggesting a function as an endogenous ligand for alpha-neurexins. The mammalian brains contain four genes for neurexophilins the products of which share a common structure composed of five domains: an N-terminal signal peptide, a variable N-terminal domain, a highly conserved central domain that is N-glycosylated, a short linker region, and a conserved C-terminal domain that is cysteine-rich. Neurexophilin-1 constitutes a secreted cysteine-rich glycoprotein, forms a very tight complex with alpha neurexins, a group of proteins that promote adhesion between dendrites and axons. Neurexophilins 1 and 3 but not 4 (neurexophilin 2 is not expressed in rodents) bind to a single individual LNS domain, the second overall LNS domain in all three alpha-neurexins.

> 85 % as determined by SDS-PAGE