Discription：NT-4 is a neurotrophic factor structurally related to β-NGF, BDNF, and NT-3. These proteins belong to the cysteine-knot family of growth factors that assume stable dimeric structures. NT-4 also named as NT-5 is a neuronal and epithelial grow factor belongs to the NGF-beta family. The NT-4 precursor is consisted of a 24 a.a. signal peptide, a 56 a.a. propertied and 130 a.a. NT-4. The mature protein has six Cys amino acid and has the relative structure with NT-3, BDNF （sharing about 48％-52％ sequence identity） . Additionally, it shares 91％ and 95％ a.a. sequence identity with mouse and rat NT-4. NT-4 is mainly expressed in prostate and has low level thymus, placenta, and skeletal muscle. It can bind with the LNGFR and trkB receptors and plays a crucial role in the regulation of survival and the maintenance of peripheral sensory sympathetic neurons. Defect of NT-4 may cause primary open angle glaucoma type 10. NT-4 can signal through the LNGFR and trkB receptors, and promotes the survival of peripheral sensory sympathetic neurons. Recombinant Human NT-4 is a noncovalently linked homodimer of two 14.0kDa polypeptide monomers （260 total amino acid） .
