Figure 1: The interaction (preference of binding) between neurotrophins and these receptors. The low-affinity receptor p75NTR binds all neurotrophins with similar affinity but not different kinetics. Trk receptors are a family of transmembrane glycoprotein, which includes three members, TrkA, TrkB, and TrkC. The full-length TrkA, TrkB, and TrkC have estimated molecular weights of 140, 145, and 145 kDa, respectively. Each Trk preferentially binds a single neurotrophin. TrkA is the receptor for NGF, both BDNF and NT-4/5 bind to TrkB, and NT-3 is the ligand for TrkC. GDNF dimer forms a complex with GFR-α1, and this complex induces dimerization of Ret. BDNF: brain-derived neurotrophic factor, GDNF: glial cell-line derived neurotrophic factor, and NT-4/5: neurotrophin-4/5.