Fig. 3

a GR-GFP fusion protein model, b GR-GFP gene construct, c microscopy images (×200) of GR-GFP and its control host. We proposed that GFP acted as a reporter gene to ensure that Gloeobacter rhodopsin was expressed with proper folding [15]. The fusion protein (GR-GFP) gene were expressed under T7 promoter in expression vector pET32a. Compared with the empty vector control, the green fluorescence could be observed in the host of E. coli BL21 expressing GR-GFP (as the white pinnacles demarcated)