The low affinity NGFR (Nerve growth factor receptor) is a 75kDa membrane-spanning glycoprotein lacking intrinsic tyrosine kinase activity. p75NGFR interacts with TrkA, the high affinity NGF receptor and potentiates TrkA signaling at low NGF concentrations. The p75 receptor binds nerve growth factor, brain-derived neurotrophic factor, neurotrophin-3 and neurotrophin-4 with varying specificities. The p75NGFR plays an important role in neurotrophic factor signaling and has been shown to modulate the susceptibility of selective cellular populations to programmed cell death. It is expressed on many neuronal cells types including many embryonic forms and the receptor can be used to isolate neuronal progenitor cells. NGF is important for the development, differentiation and survival of a variety of neuronal and non-neuronal cells. Its action is mediated by binding to two distinct receptors, the high affinity p140 and low affinity p75. p75NGFR binds neurotrophins including brain-derived neurotrophic factor (BDNF), neurotrophin-3 (NT-3), NT-4/5, and NT-6. p75NGFR belongs to the TNF-R superfamily and is reported to mediate NGF-induced apoptosis.