The role of putative phosphorylation sites in the targeting and shuttling of the aquaporin-2 water channel

van Balkom, Bas W. M., Savelkoul, Paul J. M., Markovich, Daniel, Hofman, Erik, Nielsen, Soren, van der Sluijs, Peter and Deen, Peter M. T. (2002) The role of putative phosphorylation sites in the targeting and shuttling of the aquaporin-2 water channel. Journal of Biological Chemistry, 277 44: 41473-41479. doi:10.1074/jbc.M207525200

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Author van Balkom, Bas W. M.
Savelkoul, Paul J. M.
Markovich, Daniel
Hofman, Erik
Nielsen, Soren
van der Sluijs, Peter
Deen, Peter M. T.
Title The role of putative phosphorylation sites in the targeting and shuttling of the aquaporin-2 water channel
Journal name Journal of Biological Chemistry   Check publisher's open access policy
ISSN 0021-9258
Publication date 2002-01-01
Sub-type Article (original research)
DOI 10.1074/jbc.M207525200
Open Access Status File (Publisher version)
Volume 277
Issue 44
Start page 41473
End page 41479
Total pages 7
Editor H Tabor
Place of publication Bethesda
Publisher The American Society for Biochemistry and Molecular Biology
Language eng
Subject C1
270104 Membrane Biology
780105 Biological sciences
Abstract In renal collecting ducts, a vasopressin-induced cAMP increase results in the phosphorylation of aquaporin-2 (AQP2) water channels at Ser-256 and its redistribution from intracellular vesicles to the apical membrane. Hormones that activate protein kinase C (PKC) proteins counteract this process. To determine the role of the putative kinase sites in the trafficking and hormonal regulation of human AQP2, three putative casein kinase II (Ser-148, Ser-229, Thr-244), one PKC (Ser-231), and one protein kinase A (Ser-256) site were altered to mimic a constitutively non-phosphorylated/phosphorylated state and were expressed in Madin-Darby canine kidney cells. Except for Ser-256 mutants, seven correctly folded AQP2 kinase mutants trafficked as wild-type AQP2 to the apical membrane via forskolin-sensitive intracellular vesicles. With or without forskolin, AQP2-Ser-256A was localized in intracellular vesicles, whereas AQP2-S256D was localized in the apical membrane. Phorbol 12-myristate 13-acetate-induced PKC activation following forskolin treatment resulted in vesicular distribution of all AQP2 kinase mutants, while all were still phosphorylated at Ser-256. Our data indicate that in collecting duct cells, AQP2 trafficking to vasopressin-sensitive vesicles is phosphorylation-independent, that phosphorylation of Ser-256 is necessary and sufficient for expression of AQP2 in the apical membrane, and that PMA-induced PKC-mediated endocytosis of AQP2 is independent of the AQP2 phosphorylation state.
Keyword Biochemistry & Molecular Biology
Medullary Collecting Duct
Nephrogenic Diabetes-insipidus
Vasopressin-mediated Translocation
Renal Principal Cells
Permeability Response
Q-Index Code C1
Institutional Status UQ
Additional Notes DOI: 10.1074/jbc.M207525200

Document type: Journal Article
Sub-type: Article (original research)
Collections: Excellence in Research Australia (ERA) - Collection
School of Biomedical Sciences Publications
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Created: Wed, 15 Aug 2007, 05:01:36 EST