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Trafficking defects of a novel autosomal recessive distal renal tubular acidosis mutant (S773P) of the human kidney anion exchanger (kAE1)
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Document Title
Trafficking defects of a novel autosomal recessive distal renal tubular acidosis mutant (S773P) of the human kidney anion exchanger (kAE1)
Author
Kittanakom S., Cordat E., Akkarapatumwong V., Yenchitsomanus P.-T., Reithmeier R.A.F.
Name from Authors Collection
Affiliations
Can. Inst. Hlth. Res. Grp. Memb. B., Department of Biochemistry, University of Toronto, Toronto, Ont. M5S 1A8, Canada; Inst. of Molec. Biology and Genetics, Mahidol University (Salaya Campus), Nakornpathom, Thailand; Div. of Medical Molecular Biology, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok 10700, Thailand; Medical Biotechnology Unit, Natl. Ctr. for Biotech./Genet. Eng., Natl. Sci. and Technol. Devmt. Agy., Bangkok 10700, Thailand; Dept. of Biochemistry, Medical Sciences Bldg., University of Toronto, Toronto, Ont. M5S 1A8, Canada
Type
Article
Source Title
Journal of Biological Chemistry
ISSN
00219258
Year
2004
Volume
279
Issue
39
Page
40960-40971
Open Access
Hybrid Gold
DOI
10.1074/jbc.M405356200
Abstract
Autosomal dominant and recessive distal renal tubular acidosis (dRTA) can be caused by mutations in the anion exchanger 1 (AE1 or SLC4A1) gene, which encodes the erythroid chloride/bicarbonate anion exchanger membrane glycoprotein (eAE1) and a truncated kidney isoform (kAE1). The biosynthesis and trafficking of kAE1 containing a novel recessive missense dRTA mutation (kAE1 S773P) was studied in transiently transfected HEK-293 cells, expressing the mutant alone or in combination with wild-type kAE1 or another recessive mutant, kAE1 G701D. The kAE1 S773P mutant was expressed at a three times lower level than wild-type, had a 2-fold decrease in its half-life, and was targeted for degradation by the proteasome. It could not be detected at the plasma membrane in human embryonic kidney cells and showed predominant endoplasmic reticulum immunolocalization in both human embryonic kidney and LLC-PK1 cells. The oligosaccharide on a kAE1 S773P N-glycosylation mutant (N555) was not processed to the complex form indicating impaired exit from the endoplasmic reticulum. The kAE1 S773P mutant showed decreased binding to an inhibitor affinity resin and increased sensitivity to proteases, suggesting that it was not properly folded. The other recessive dRTA mutant, kAE1 G701D, also exhibited defective trafficking to the plasma membrane. The recessive kAE1 mutants formed dimers like wild-type AE1 and could hetero-oligomerize with wild-type kAE1 or with each other. Hetero-oligomers of wild-type kAE1 with recessive kAE1 S773P or G701D, in contrast to the dominant kAE1 E589H mutant, were delivered to the plasma membrane.
License
CC BY or CC BY-NC-ND
Rights
Elsevier B.V.
Publication Source
Scopus