The p75 neurotrophin receptor (p75^NTR) is a member of the TNF receptor superfamily. p75^NTR, like all the superfamily members is a type I transmembrane protein with tandem cysteine-rich domains in the extracellular portion and a intracellular death domain. p75^NTR binds its ligands as a homodimer but can also form heterodimers with other receptors such as TrkA, TrkB, TrkC, Nogo receptor and sortilin. The precise multimeric receptor complex formed between p75^NTR and the other receptors will determine the ligand being recognized (see below) and the biological response to its binding.

As it name implies, p75^NTR binds all the neurotrophins (NGF, BDNF, NT-3 and NT-4) with similar nM affinities. Co-expression of p75^NTR with the Trk receptors enhances the ability to bind and respond to the specific neurotrophin and induces cell survival. On the other hand, it has recently been demonstrated that p75^NTR binds with high affinity to the unprocessed form of NGF (proNGF) probably as a complex with sortilin and this leads to cell death by apoptosis. Finally, a multimeric complex of p75^NTR and Nogo receptor binds myelin proteins such as Nogo-66, MAG and OmgP resulting in inhibition of axonal growth.