title: Impaired trafficking of human kidney anion exchanger (kAE1) caused by hetero-oligomer formation with a truncated mutant associated with distal renal tubular acidosis.
abstract: Autosomal dominant distal renal tubular acidosis (dRTA) has been associated with several mutations in the anion exchanger AE1 gene. The effect of an 11-amino-acid C-terminal dRTA truncation mutation (901 stop) on the expression of kidney AE1 (kAE1) and erythroid AE1 was examined in transiently transfected HEK-293 cells. Unlike the wild-type proteins, kAE1 901 stop and AE1 901 stop mutants exhibited impaired trafficking from the endoplasmic reticulum to the plasma membrane as determined by immunolocalization, cell-surface biotinylation, oligosaccharide processing and pulse-chase experiments. The 901 stop mutants were able to bind to an inhibitor affinity resin, suggesting that these mutant membrane proteins were not grossly misfolded. Co-expression of wild-type and mutant kAE1 or AE1 resulted in intracellular retention of the wild-type proteins in a pre-medial Golgi compartment. This dominant negative effect was due to hetero-oligomer formation of the mutant and wild-type proteins. Intracellular retention of kAE1 in the alpha-intercalated cells of the kidney would account for the impaired acid secretion into the urine characteristic of dRTA.
authors.affiliation: Department of Biochemistry, Room 5205, Medical Sciences Building, University of Toronto, Toronto, Ontario, Canada M5S 1A8.
authors.forename: Janne A
authors.initials: JA
authors.lastname: Quilty
authors.forename: Emmanuelle
authors.initials: E
authors.lastname: Cordat
authors.forename: Reinhart A F
authors.initials: RA
authors.lastname: Reithmeier
mesh_terms: D012856:4-Acetamido-4'-isothiocyanatostilbene-2,2'-disulfonic Acid / Q000494:pharmacology; D000141:Acidosis, Renal Tubular / Q000235:genetics* / Q000378:metabolism; D001457:Anion Exchange Protein 1, Erythrocyte / Q000235:genetics* / Q000378:metabolism*; D019921:Biotinylation; D015153:Blotting, Western; D002460:Cell Line; D002462:Cell Membrane / Q000378:metabolism; D004721:Endoplasmic Reticulum / Q000378:metabolism; D005799:Genes, Dominant; D006031:Glycosylation; D006801:Humans; D007150:Immunohistochemistry; D007668:Kidney / Q000378:metabolism; D009154:Mutation; D009844:Oligosaccharides / Q000737:chemistry; D010957:Plasmids / Q000378:metabolism; D017434:Protein Structure, Tertiary; D013997:Time Factors; D014162:Transfection
chemical_list: D001457:Anion Exchange Protein 1, Erythrocyte; D009844:Oligosaccharides; C454201:SLC4A1 protein, human; D012856:4-Acetamido-4'-isothiocyanatostilbene-2,2'-disulfonic Acid