Recombinant Human Neurexophilin-1/NXPH1 Protein, CF

Neurexophilin-1 (NXPH1) is one of at least four vertebrate neuropeptide-like secreted glycoproteins in the neurexophilin family (1, 2). The 271 amino acid (aa) NXPH1 sequence contains a 21 aa signal peptide, an 86 aa propeptide that is cleaved at a basic motif, and a 164 aa mature protein that contains three potential N-glycosylation sites in the N-terminal portion and six conserved cysteines in the C-terminal portion (1). Mature human NXPH1 shares 99% aa identity with mouse, rat, equine, bovine and canine NXPH1. NXPH1 is expressed selectively in subpopulations of neurons within the cerebral cortex, cerebellum and olfactory bulb that are thought to be inhibitory interneurons (2, 3). In humans, NXPH-2 and -3 are most similar to NXPH1, sharing 84% and 64% aa identity within the mature region, respectively. In rodents, which do not express NXPH-2, expression of NXPH1 and NXPH-3 does not appear to coincide. However, both serve as tightly bound extracellular ligands for alpha -neurexins, synaptic transmembrane molecules that are essential for calcium-triggered neurotransmitter release (1, 4, 5). By contrast, NXPH-4 does not bind alpha -neurexins (1, 4). Genetic deletion of NXPH1 and/or NXPH-3 produces no anatomical effect, although mice lacking NXPH-3 show defects in motor coordination (4, 6).