Figure 4.

Increasing the length of BDNF-fusion proteins attenuates their ability to phosphorylate TrkB. A, Western blot analysis of cell lysates and conditioned media using anti-BDNF (mAb 3C11). Cells were transfected with cDNAs encoding BDNF carrying multiple additions of the 10 aa myc tag. B, TrkB phosphorylation in primary neurons treated with conditioned media containing BDNF fusion proteins standardized to 25 ng/ml. Note that the potency of TrkB phosphorylation is significantly reduced as genetically encoded tags increase in length (BDNF-3 myc, *p = 0.00312; BDNF-4 myc, *p = 0.00394). Bars representative of mean relative phosphorylation (compared with BDNF-myc) ± SE.