Brain-derived neurotrophic factor is the second member of the neurotrophin-family trophic factors. BDNF is a polypeptide consisting of 119 amino acid residues, and forms a homodimer. There are two types of receptors binding to BDNF: tropomyosin receptor kinase B (TrkB), the high-affinity receptor, and p75NTR, the low affinity receptor. BDNF regulates the growth, maintenance, and survival of certain target neurons as well as the synaptic plasticity, learning, and memory through the activation of TrkB. On the other hand, the role of p75NTR is less clear.
