Nerve growth factor receptors(NGFRs or P75) include high-affinity nerve growth factor receptor and low-affinity nerve growth factor receptor. High-affinity nerve growth factor receptor is also known as TrkA. Nerve growth factor
binds with TrkA after being released from target cells, the NGF / TrkA complex is subsequently trafficked back to the cell body. NGFLow-affinity nerve growth factor receptor also named p75 neurotrophin receptor. All the four kinds of neurotrophins, including Nerve growth factor, Brain derived neurotrophic factor, Neurotrophin-3, and Neurotrophin-4 bind to the p75NTR. It has been demonstrated that NGF acts through its low-affinity receptor p75NTR. Studies have proved that NGFR acts as a molecular signal swith that determines cell death or survival by three steps. First, pro-nerve growth factor (prNGF) triggers cell apoptosis by its high affinity binding to p75NTR, while NGF induces neuronal survival with low-affinity binding. Second, p75NTR mediates cell death by combining with co-receptor sortilin, whereas it promotes neuronal survival through combination with proNGF. Third, release of the intracellular domain chopper or cleavage short p75 NTR can independently initiate neuronal apoptosis.