Fig. 4. Biochemical quantification of cell surface localized HASPB-GFP fusion proteins. CHO cells expressing HASPB-GFP fusion proteins as indicated were treated with a membrane-impermeable biotinylation reagent. Cell lysates were generated and biotin-labeled and biotin-unlabeled proteins were separated by streptavidin affinity chromatography. Input material (lane 1; 2%), streptavidin supernatant (non-biotinylated proteins, lane 2; 2%) and streptavidin-bound proteins (biotinylated proteins, lane 3; 50%) were separated on SDS gels followed by western blotting using affinity-purified anti-GFP antibodies.