Due to the various splice variants, the trk proteins exist as variably glycosylated entities with the major forms having molecular weights of 140-145 kDa, 110 kDa and the unglycosylated form of 80 kDa. trkB contains 33.3% carbohydrate by weight representing modification on 10 of 12 N-glycosylation sites. The primary ligand for trkB is BDNF which induces the phosphorylation of the protein and subsequent binding of PLC-gamma via SH2 domains. TrkB may function to modulate neuronal responses to the neurotrophins acting throμgh trkB such as BDNF.