Interaction between polySia-NCAM and BDNF. Top, titration of BDNF with STX(WT)-derived polySia-NCAM (7–900 ng as BSA); middle, titration of BDNF with STX(G421A)-derived polySia-NCAM (7–900 ng as BSA); bottom, titration of BDNF with STX(C621G)-derived polySia-NCAM (7–900 ng as BSA). The principle of this method was well described (28). The calculated EC50 values are indicated below each gel. +, anode region; −, cathode region; >, loaded position. The BDNF-polySia-NCAM complex is boxed by a dotted line.