|Detection of Human and Mouse Neurexin 3/NRXN3 by Western Blot. Western blot shows lysates of mouse brain tissue and SH‑SY5Y human neuroblastoma cell line. PVDF membrane was probed with 1 µg/mL of Sheep Anti-Human/Mouse Neurexin 3/NRXN3 Antigen Affinity-purified Polyclonal Antibody (Catalog # AF5269) followed by HRP-conjugated Anti-Sheep IgG Secondary Antibody (Catalog # HAF016). A specific band was detected for Neurexin 3/NRXN3 at approximately 160-170 kDa (as indicated). This experiment was conducted under reducing conditions and using Immunoblot Buffer Group 8.|
The alpha and beta forms of Neurexins 1‑3 are transmembrane neuronal glycoproteins which are transcribed from each of three NRXN genes that utilize alternate promoters. Like other Neurexins, the extracellular domain (ECD) of Neurexin 3 alpha contains six LNS domains interspersed with three EGF-like domains, while that of Neurexin 3 beta contains only the sixth LNS domain and no EGF-like domains (1‑3). Mature human Neurexin 3 beta is a 70 kDa glycosylated protein with a 528 amino acid (aa) ECD and a 56 aa cytoplasmic domain that contains a motif for binding PDZ scaffolding proteins (3‑5). Within comparable regions of the ECD, human Neurexin 3 beta shares 99% aa sequence identity with mouse and rat Neurexin 3 beta. It shares 65% aa sequence identity with comparable regions of the ECD of human Neurexin 1 beta and 2 beta. Alternative splicing of human Neurexin 3 beta generates multiple isoforms. There are potentially soluble and secreted variants and some which contain a fibronectin type III-like domain (4, 6). Neurexin 3 beta is widely expressed in the brain where it binds the postsynaptic Neuroligins 1, 2, and 3 (6‑9). Neurexin 3 beta may also be expressed in non-nervous tissues with a potentially cardiac-specific isoform (10). Human Neurexin 3 beta polymorphisms which affect the splicing pattern are associated with susceptibility to alcohol dependence (6). The Neurexin 3 beta genetic locus has been linked to opioid and nicotine addiction, and Neurexin 3 beta gene expression is up‑regulated after short term exposure of mice to cocaine (11‑13).