Fig. 2.

TrkB signaling. Upon ligand-binding (BDNF or NT-4/5), the receptor (which itself is a tyrosine kinase) undergoes transactivation by phosphorylation at tyrosine residues within the catalytic domain (Y705, is one such residue) and at other tyrosine residues such as Y515 and Y816. Phosphorylation at these latter two residues triggers distinct downstream signaling cascades which can eventually lead to gene transcription, cell proliferation and survival. BDNF, brain derived neurotrophic factor; NT, neurotrophin.