Neurotrophic factor receptor

Neurotrophic factor receptors or neurotrophin receptors are a group of growth factor receptors which specifically bind to neurotrophins (neurotrophic factors).
Two classes of neurotrophic factor receptors are the p75 and the "Trk" families of Tyrosine kinases receptors.
TrkA, B, and C receptors.
TrkA mediates its actions by causing the addition of phosphate molecules on certain tyrosines in the cell, activating cellular signaling.
There are other related Trk receptors (TrkB and TrkC), and there are other neurotrophic factors structurally related to NGF (BDNF, NT-3, and NT-4)
p75NTR receptor.
The Low affinity nerve growth factor receptor commonly known as "p75", can signal for apoptosis or promote neuronal survival. Neurotrophins that interact with p75NTR include NGF, NT-3, BDNF, and NT-4/5. Neurotrophins activating p75NTR may initiate apoptosis (for example, via c-Jun N-terminal kinases signaling), and this effect can be counteracted by anti-apoptotic signaling by TrkA. Neurotrophin binding to p75NTR can promote neuronal survival (for example, via NF-kB activation).
Although NGF has been classically described as promoting neuron survival and differentiation, research performed in the early 2000s suggest that NGF with its prodomain attached (proNGF) can elicit apoptosis of cells that are positive for the LNGFR and negative for TrkA.
Secreted proNGF has been demonstrated in a variety of neuronal and non-neuronal cell populations. It has been proposed that secreted proNGF can elicit neuron death in a variety of neurodegenerative conditions, including Alzheimer's disease, following the observation of an increase of proNGF in the nucleus basalis of postmortem Alzheimer's brains .
Further reading.
Review papers offer overviews and drawings of p75NTR pathways.