Fig. 4. Residues 20-40 of the KCNQ1 protein is important for steady-state localisation at the basolateral membrane. (A) Expression of wt-KCNQ1 and deletion mutants 20-KCNQ1 and 40-KCNQ1 in MDCK cells. The top panel shows a horizontal confocal scan through the cell layer at the basal level, whereas the bottom panel shows vertical confocal scans of the same cells. Bar, 8 µm. (B) The majority of sKvLQT1 staining in polarised MDCK cells is observed in intracellular compartments. Confocal scans of MDCK cells transfected with sK_VLQT1 alone and cells co-transfected with sKvLQT1 and KCNE1. The fixed cells were labeled for sKvLQT1. Biotinylation of the apical membrane is applied (in green) to the vertical confocal scans. Ap, apical membrane, Ba, basal membrane. Bar, 8 µm.