Aquaporin 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.

AQP2
Available structures PDB Ortholog search: PDBe RCSB List of PDB id codes 4OJ2, 4NEF
Identifiers
Aliases	AQP2, AQP-CD, WCH-CD, aquaporin 2
External IDs	OMIM: 107777 MGI: 1096865 HomoloGene: 20137 GeneCards: AQP2
Gene location (Human) Chr. Chromosome 12 (human)[1] Band 12q13.12 Start 49,950,741 bp[1] End 49,958,881 bp[1]
Gene location (Mouse) Chr. Chromosome 15 (mouse)[2] Band 15 F1|15 56.13 cM Start 99,579,055 bp[2] End 99,584,547 bp[2]
RNA expression pattern More reference expression data
Gene ontology Molecular function • transporter activity • glycerol transmembrane transporter activity • water transmembrane transporter activity • water channel activity • GO:0001948 protein binding • channel activity Cellular component • integral component of membrane • recycling endosome • Golgi apparatus • membrane • cell membrane • transport vesicle membrane • basolateral plasma membrane • apical plasma membrane • extracellular exosome • cytoplasmic vesicle membrane • cytoplasmic vesicle • integral component of plasma membrane • lumenal side of membrane Biological process • cellular response to mercury ion • excretion • water transport • ion transmembrane transport • renal water transport • renal water homeostasis • cellular response to copper ion • metanephric collecting duct development • cellular response to water deprivation • glycerol transport • transport • transmembrane transport • protein homotetramerization Sources:Amigo / QuickGO
Orthologs
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	[3]	[4]
Wikidata
View/Edit Human View/Edit Mouse

RegulationEdit

It is the only aquaporin regulated by vasopressin.^[5] 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. When it is needed, vasopressin binds to the cell surface vasopressin receptor thereby 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.^[6] 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 significanceEdit

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.

This article uses material from the Wikipedia article  Metasyntactic variable, which is released under the  Creative Commons Attribution-ShareAlike 3.0 Unported License.