Figure 4. CNGB3 F525N mutation increases annexin V–positive cells compared to wild-type channels. Transfected cells were treated with 0.1 μM CPT-cGMP for 24 h. For determination of cell death, cells were stained with fluorescein-labeled annexin V, a protein with a high affinity for phosphatidylserine (A and B). Cells were also counterstained with DAPI to count nuclei (C and D), and the two images were merged to count annexin V–positive cells (E and F). G: Summary bar graph for annexin V staining of cells transfected with control plasmid, wild-type CNGB3 plus CNGA3, or CNGB3-F525N plus CNGA3 plasmids. Fluorescent images were obtained using a Zeiss LSM 510 confocal system as described in the Methods. Scale bar in F (applies to A-F), 100 µm.