Impaired trafficking of human kidney anion exchanger (kAE1) caused by hetero-oligomer formation with a truncated mutant associated with distal renal tubular acidosis.
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.
Quilty
Janne A
JA
Department of Biochemistry, Room 5205, Medical Sciences Building, University of Toronto, Toronto, Ontario, Canada M5S 1A8.
Cordat
Emmanuelle
E
Reithmeier
Reinhart A F
RA
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
D001457:Anion Exchange Protein 1, Erythrocyte; D009844:Oligosaccharides; C454201:SLC4A1 protein, human; D012856:4-Acetamido-4'-isothiocyanatostilbene-2,2'-disulfonic Acid