Fig. 3.

QD-BDNF binds specifically to TrkB receptors. COS7 cells that did not express endogenous TrkB were transfected with a TrkB-GFP plasmid. When 4 nM QD-BDNF was supplied to transfected cell culture, QD binding and internalization was specific to the transfected cells (green cell) as shown in the left panel images. The non-transfected cells have very little QD binding even after 2hrs of incubation. When a mixture of 4 nM QD and 4 nM unmodified BDNF was applied to the culture, very few QD binding events were observed in either transfected or non-transfected cells (right panel images).