Co-localization of the endoplasmic reticulum (ER) marker Calnexin and selected ABCC6 mutants.

The liver cells expressing the human ABCC6 variants (WT, R1339C, R1138Q and R1314W) were visualized by immunofluorescence on liver frozen sections using the M6II-31 monoclonal antibody (green) and a rabbit polyclonal antibody to the mouse ER marker Calnexin (red). Minimal co-localization (yellow) was seen between Calnexin and the WT and R1138Q mutant, while some spotty co-localization was visible for the R1339C mutant, primarily around the nuclei indicating partial ER retention or slower trafficking of this variant. The R1314W mutant showed the highest level of co-localization, which suggested that a large fraction of this protein is unable to leave the ER and translocate to the plasma membrane. Scale is shown on the upper left image (50 µm).