Tropomyosin Receptor Kinase B (TrkB)

TrkB is the high affinity catalytic receptor for several "neurotrophins", which are small protein growth factors that induce the survival and differentiation of distinct cell populations. The neurotrophins that activate TrkB are: Brain Derived Neurotrophic Factor, or "BDNF", NT-4 (neurotrophin-4), and NT-3 (neurotrophin-3). As such, TrkB mediates the multiple effects of these neurotrophic factors, which includes neuronal differentiation and survival. The TrkB receptor is part of the large family of receptor tyrosine kinases. A "tyrosine kinase" is an enzyme which is capable of adding a phosphate group to certain tyrosines on target proteins, or "substrates". A receptor tyrosine kinase is a "tyrosine kinase" which is located at the cellular membrane, and is activated by binding of a ligand to the receptor's extracellular domain.