FIGURE 3.

C terminus of SNAT4 faces the extracellular side of the cell. A, CHO cells expressing exogenous c-myc-tagged SNAT4 were immunolabeled with anti-c-myc antibody in the absence of Triton X-100. Nuclei were counterstained with DAPI. Scale bar, 20 μm. B, Cys-null mutant was generated by replacing all endogenous cysteines with alanines. The N543C mutant was generated using the Cys-null mutant as a template. Cells expressing WT, N543C, and vector control were labeled with MTSEA-biotin. The isolated biotinylated proteins (upper) and the preloaded cell lysates (lower) were immunoblotted with anti-SNAT4 antibody or anti-GAPDH antibody.