AQP2 is a substrate for endogenous PP2B activity within an inner medullary AKAP-signaling complex
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- Inho Jo
- Division of Nephrology, Children's Hospital, Harvard Medical School, Boston, Massachusetts 02115;
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- Donald T. Ward
- Division of Nephrology, Children's Hospital, Harvard Medical School, Boston, Massachusetts 02115;
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- Michelle A. Baum
- Division of Nephrology, Children's Hospital, Harvard Medical School, Boston, Massachusetts 02115;
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- John D. Scott
- Vollum Institute, Howard Hughes Medical Institute, and
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- Vincent M. Coghlan
- Neurological Sciences Institute, Oregon Health Sciences University, Portland, Oregon 97201;
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- Timothy G. Hammond
- Tulane University Medical Center and Veterans Affairs Medical Center, New Orleans, Louisiana 70112; and
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- H. William Harris
- Division of Nephrology, Children's Hospital, Harvard Medical School, Boston, Massachusetts 02115;
書誌事項
- 公開日
- 2001-11-01
- DOI
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- 10.1152/ajprenal.2001.281.5.f958
- 公開者
- American Physiological Society
この論文をさがす
説明
<jats:p>We have demonstrated that inner medullary collecting duct (IMCD) heavy endosomes purified from rat kidney IMCD contain the type II protein kinase A (PKA) regulatory subunit (RII), protein phosphatase (PP)2B, PKCζ, and an RII-binding protein (relative molecular mass ∼90 kDa) representing a putative A kinase anchoring protein (AKAP). Affinity chromatography of detergent-solubilized endosomes on cAMP-agarose permits recovery of a protein complex consisting of the 90-kDa AKAP, RII, PP2B, and PKCζ. With the use of small-particle flow cytometry, RII and PKCζ were localized to an identical population of endosomes, suggesting that these proteins are components of an endosomal multiprotein complex.<jats:sup>32</jats:sup>P-labeled aquaporin-2 (AQP2) present in these PKA-phosphorylated endosomes was dephosphorylated in vitro by either addition of exogenous PP2B or by an endogenous endosomal phosphatase that was inhibited by the PP2B inhibitors EDTA and the cyclophilin-cyclosporin A complex. We conclude that IMCD heavy endosomes possess an AKAP multiprotein-signaling complex similar to that described previously in hippocampal neurons. This signaling complex potentially mediates the phosphorylation of AQP2 to regulate its trafficking into the IMCD apical membrane. In addition, the PP2B component of the AKAP-signaling complex could also dephosphorylate AQP2 in vivo.</jats:p>
収録刊行物
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- American Journal of Physiology-Renal Physiology
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American Journal of Physiology-Renal Physiology 281 (5), F958-F965, 2001-11-01
American Physiological Society