Fig. 8. Cell-surface expression of CONT depends on NRX IV. Neuroblastoma N2a cells were transfected with NRX IV or CONT, or co-transfected with both constructs. (A) NRX IV is efficiently transported to the cell surface in the absence of CONT. (B-D) When transfected alone, CONT is not expressed at the plasma membrane. Double-immunostaining of CONT (B, red) and the ER marker BiP (C, green). The merged image (D) shows that CONT is retained in the ER (arrowheads). (E-H) Co-transfection of CONT (E) and NRX IV (F) in N2a cells results in expression of CONT protein at the plasma membrane. (G,H) Cell-surface expression of CONT in N2a cells co-transfected with CONT and NRX IV. Cells were fixed, permeabilized with Triton X-100 and processed for immunofluorescence staining in A-F. Immunostaining for CONT was carried out on living cells in G and then cells were fixed, permeabilized and processed for NRX IV immunostaining (H). Scale bar: 10 µm.