Expression of normal and mutant GFP-tagged y(+)L amino acid transporter-1 in mammalian cells.
Lysinuric protein intolerance (LPI; MIM 222700) is an autosomal recessive disorder characterized by defective transport of cationic amino acids lysine, arginine and ornithine. The defect is localized in the basolateral membrane of polar epithelial cells of the renal tubules and intestine. The SLC7A7 (solute carrier family 7, member 7) gene that encodes y(+)LAT-1 (y(+)L amino acid transporter-1) is mutated in LPI, and leads to the malfunction of the heterodimer composed of y(+)LAT-1 and 4F2hc (4F2 heavy chain) responsible for the system y(+)L amino acid transport activity at the membrane. In this study, the intracellular trafficking and membrane expression of wild type and four mutant y(+)LAT-1 proteins (LPI(Fin), G54V, 1548delC, W242X) was studied in two human cell lines by expressing green fluorescent protein (GFP) tagged proteins. Different SLC7A7 mutations influenced the trafficking of y(+)LAT-1 in the cells differently, as the wild type and missense mutant fusion proteins localized to the plasma membrane, while the frameshift and nonsense mutants sequestered to the cytoplasmic membranes, never reaching the target areas of the cell.
Toivonen
Minna
M
Department of Medical Genetics, University of Turku, Kiinamyllynkatu 10, FIN-20520 Turku, Finland. mihehe@utu.fi
Mykkänen
Juha
J
Aula
Pertti
P
Simell
Olli
O
Savontaus
Marja-Liisa
ML
Huoponen
Kirsi
K
D027241:Amino Acid Transport System y+L; D015152:Blotting, Northern; D002478:Cells, Cultured; D027301:Fusion Regulatory Protein 1, Light Chains / Q000096:biosynthesis* / Q000235:genetics; D049452:Green Fluorescent Proteins; D006801:Humans; D008164:Luminescent Proteins / Q000235:genetics / Q000378:metabolism; D009154:Mutation; D011993:Recombinant Fusion Proteins / Q000378:metabolism
D027241:Amino Acid Transport System y+L; D027301:Fusion Regulatory Protein 1, Light Chains; D008164:Luminescent Proteins; D011993:Recombinant Fusion Proteins; C421261:SLC7A7 protein, human; D049452:Green Fluorescent Proteins