Serine 269 phosphorylated aquaporin-2 is targeted to the apical membrane of collecting duct principal cells

Kidney Int. 2009 Feb;75(3):295-303. doi: 10.1038/ki.2008.505. Epub 2008 Oct 8.


Trafficking of the water channel aquaporin-2 to the apical plasma membrane of the collecting duct is mediated by arginine vasopressin, rendering the cell permeable to water. We recently identified a novel form of aquaporin-2 that is phosphorylated at serine-269 (pS269-AQP2). Using antibodies specific for this form of the water channel, we detected rat and mouse pS269-AQP2 in the connecting tubule and throughout the collecting duct system. Using confocal immunofluorescence microscopy with organelle-specific markers and immunogold electron microscopy, we found that pS269-AQP2 was found only on the apical plasma membrane of principal cells. In vasopressin-deficient Brattleboro rats, pS269-AQP2 was undetectable but dramatically increased in abundance after these rats were treated with [deamino-Cys-1, d-Arg-8]vasopressin (dDAVP). This increase occurred only at the apical plasma membrane, even after long-term dDAVP treatment. Following dDAVP there was a time-dependent redistribution of total aquaporin-2 from predominantly intracellular vesicles to the apical plasma membrane, clathrin-coated vesicles, early endosomal compartments, and lysosomes. However, pS269-AQP2 was found only on the apical plasma membrane at any time. Our results show that S269 phosphorylated aquaporin-2 is exclusively associated with the apical plasma membrane, where it escapes endocytosis to remain at the cell surface.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Aquaporin 2 / metabolism*
  • Aquaporin 2 / ultrastructure
  • Cell Membrane / metabolism*
  • Cell Membrane / ultrastructure
  • Clathrin-Coated Vesicles / metabolism
  • Deamino Arginine Vasopressin / metabolism
  • Deamino Arginine Vasopressin / pharmacology
  • Endosomes / metabolism
  • Endosomes / ultrastructure
  • Immunohistochemistry
  • Kidney Tubules, Collecting / cytology*
  • Kidney Tubules, Collecting / metabolism*
  • Kidney Tubules, Collecting / ultrastructure
  • Lysosomes / metabolism
  • Lysosomes / ultrastructure
  • Mice
  • Mice, Inbred C57BL
  • Mice, Knockout
  • Peroxidase / immunology
  • Peroxidase / metabolism
  • Phosphorylation
  • Rats
  • Rats, Brattleboro
  • Rats, Wistar
  • Sensitivity and Specificity
  • Serine / metabolism*
  • Time Factors


  • Aquaporin 2
  • Serine
  • Peroxidase
  • Deamino Arginine Vasopressin