Aquaporin 2

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Aquaporin 2 (collecting duct)
Available structures
PDB Ortholog search: PDBe, RCSB
Symbols AQP2 ; AQP-CD; WCH-CD
External IDs OMIM107777 MGI1096865 HomoloGene20137 IUPHAR: 689 GeneCards: AQP2 Gene
RNA expression pattern
PBB GE AQP2 206672 at tn.png
More reference expression data
Species Human Mouse
Entrez 359 11827
Ensembl ENSG00000167580 ENSMUSG00000023013
UniProt P41181 P56402
RefSeq (mRNA) NM_000486 NM_009699
RefSeq (protein) NP_000477 NP_033829
Location (UCSC) Chr 12:
49.95 – 49.96 Mb
Chr 15:
99.58 – 99.58 Mb
PubMed search [1] [2]

AQP2 is found in the apical cell membranes of the kidney's collecting duct principal cells and in intracellular vesicles located throughout the cell.


It is the only aquaporin regulated by vasopressin.[1] The basic job of aquaporin 2 is to reabsorb water from the urine while its being removed from the blood by the kidney. Aquaporin 2 is in kidney epithelial cells and usually lies dormant in intracellular vesicle membranes, but when it is needed vasopressin binds to the cell surface vasopressin receptor, activating a signaling pathway that causes the aquaporin 2 containing vesicles to fuse with the plasma membrane so the aquaporin 2 can be used by the cell.[2]

This aquaporin is regulated in two ways by the peptide hormone vasopressin:

  • short-term regulation (minutes) through trafficking of AQP2 vesicles to the apical region where they fuse with the apical plasma membrane
  • long-term regulation (days) through an increase in AQP2 gene expression.

This aquaporin is also regulated by food intake. Fasting reduces expression of this aquaporin independently of vasopressin.

Clinical significance[edit]

Mutations in this channel are associated with nephrogenic diabetes insipidus, which can be autosomal dominant or recessive. Mutations in the vasopressin receptor cause a similar X-linked phenotype.

Lithium, which is often used to treat bipolar disorder, can cause acquired diabetes insipidus (characterized by the excretion of large volumes of dilute urine) by decreasing the expression of the AQP2 gene.

The expression of the AQP2 gene is increased during conditions associated with water retention such as pregnancy and congestive heart failure.

See also[edit]


  1. ^ Dibas AI, Mia AJ, Yorio T (1998). "Aquaporins (water channels): role in vasopressin-activated water transport". Proc. Soc. Exp. Biol. Med. 219 (3): 183–99. doi:10.3181/00379727-219-44332. PMID 9824541. 
  2. ^ Lodish, Harvey F. Molecular Cell Biology. New York: W.H. Freeman, 2008. Print. 445.

Further reading[edit]

External links[edit]