FIGURE 4.

Identification of extracellular loop domains of SNAT4 using MTSEA-biotin chemical labeling. DNA constructs containing single cysteine (T129C, A183C, L219C, 232C, 249C, 321C, 345C, T366C, A401C, T440C, I474C, and L507C) on the Cys-null template of SNAT4 were generated and transfected into CHO cells. The cells were labeled with MTSEA-biotin, and the isolated biotinylated proteins (upper) and the preloaded cell lysates (lower) were immunoblotted with anti-SNAT4 antibody or anti-GAPDH antibody. A, amino acid residues at positions 183, 249, and 321 are located at the extracellular loop domains. B, amino acid residue at 401 is located at an extracellular loop domain.