Activation of NTRK2 (TrkB) by binding to BDNF or NTF4 (NT-4) leads to phosphorylation of FRS2 (also known as SNT or FRS2alpha) (Yuen and Mobley 1999). FRS2 binds to phosphorylated tyrosine Y516 of activated NTRK2 (Zeng et al. 2014 - Y516 is mislabeled as Y512 in the paper). Human FRS2 was also shown to bind to intracellular domain of rat Ntrk2 (Dixon et al. 2006).