Fig. 5. Determination of ZnT-8 membrane topology. (A) Confocal microscopy images of INS-1E-ZnT-8-EGFP cells, incubated with anti-ZnT-8 antibodies 9A or 9B (see Materials and Methods) before or after membrane permeabilization. The EGFP signal is present in both permeabilized and non-permeabilized cells, whereas antibodies recognize the ZnT-8 protein only after permeabilization. Bars, 15 µm. (B) Proposed model for the membrane topology of ZnT-8. Gray boxes indicate location of antibody epitopes, 9A, 9B. HIS, histidine-rich region; Ct, C-terminus; Nt, N-terminus.