Fig. 3. Differential endocytic targeting of PLP, MAG and MOG. (A) Colabeling of endocytosed proteins with endocytic markers. Transfected Oli-neu cells were allowed to endocytose surface-bound antibodies for 1 hour at 37°C. During the endocytosis period, labeling of recycling endosomes was achieved by co-endocytosis of transferrin-FITC (bottom images, green). To label LE/Lys, cells were immunostained using anti-LAMP1 antibodies (top images, green). Confocal images show colocalization of PLP and MAG with LAMP1 in LE/Lys (top images, yellow). MOG colocalized with transferrin-FITC in the recycling endosomes (bottom image, yellow). (B) Co-endocytosis of PLP (red) and MAG (green), performed by simultaneous antibody uptake. Cell-surface-localized proteins were counterstained in blue and thus appear cyan, magenta or white. After 5 minutes of endocytosis PLP and MAG are localized to distinct populations of early endosomes (red and green dots). Colocalization of endocytosed PLP and MAG increases over 10 and 30 minutes of endocytosis (yellow dots). Insets show enlarged areas. Scale bars: 5 µm.