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Fig. 5 | Genome Medicine

Fig. 5

From: Global genetic analyses reveal strong inter-ethnic variability in the loss of activity of the organic cation transporter OCT1

Fig. 5

Subcellular localization and glycosylation patterns of the isoforms encoded by the major OCT1 alleles. a The subcellular localization of the OCT1 isoforms showing that the major cause for substrate-wide loss of OCT1 activity is improper subcellular localization. Shown are the OCT1-overexpressing HEK293 cells stably transfected with alleles causing substrate-wide loss of OCT1 function, and the HEK293 cells expressing the wild type (OCT1*1) as a reference. The subcellular localization was analyzed with confocal microscopy after immunocytochemical staining for OCT1 (green). The exact OCT1 localization was analyzed using co-staining with Na+/K+ ATPase (red, upper part) as a marker for the plasma membrane and calnexin (red, lower part) as a marker for the endoplasmic reticulum. The immunocytochemical analyses of the sub-alleles and the alleles causing gain or substrate-specific loss of OCT1 function are shown in Additional file 13. b Western blot analyses of total cellular protein illustrating differences between the glycosylation patterns of OCT1 isoforms correctly localized in the plasma membrane and those retained in the endoplasmic reticulum. OCT1 was detected as a double signal of a close to 70 kDa large PNGaseF-sensitive and EndoH-resistant glycosylation form and a 50 kDa EndoH-sensitive glycosylation form. Glyceraldehyde-3-phosphate dehydrogenase (GAPDH) was used as a loading control

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