P75NTR (or CD271) is a member of the Tumor Necrosis Factor receptor (TNFR) super family of transmembrane proteins that share significant homology in their extracellular domains. Subsets of TNF receptors, including CD271, have a cytoplasmic death domain, although CD271 has unique intracellular structure and downstream signaling partners. CD271 is also differentiated from other members of the TNFR receptor family in that it binds pro and mature neurotrophins and affects the growth, differentiation and death of the nervous system. The ligands for CD271 are neurotrophins, which are Nerve Growth Factor (NGF), Brain-Derived Growth factor (BDNF), Neurotrophin 3 (NT3) and Neurotrophin 4/5 (NT4/5). Recent studies have provided evidence that CD271 also serves as a receptor for the pro-forms of these neurotrophins.