β-NGF is a neurotrophic factor structurally related to BDNF, NT-3 and NT-4. These proteins belong to the cysteine-knot family of growth factors that assume stable dimeric structures. β-NGF is a potent neurotrophic factor that signals through its receptor β-NGFR, and plays a crucial role in the development and preservation of the sensory and sympathetic nervous systems. β-NGF also acts as a growth and differentiation factor for B lymphocytes and enhances B-cell survival. The functional form of murine β-NGF is a noncovalently disulfide-linked homodimer, of two 13.4 kDa polypeptide monomers (240 total amino acid residues). The three disulfide bonds are required for biological activity.