Aquaporin 4

Aquaporin 4
Double layered 2D crystal structure of aquaporin-4 (AQP4M23) at 3.2 a resolution by electron crystallography.
Available structures PDB 2d57
Identifiers
Symbols	AQP4; HMIWC2; MGC22454; MIWC
External IDs	OMIM: 600308 MGI: 107387 HomoloGene: 37507 GeneCards: AQP4 Gene
Gene Ontology Molecular function • transporter activity • water transmembrane transporter activity • water channel activity Cellular component • cytoplasm • plasma membrane • plasma membrane • integral to plasma membrane • cell-cell junction • external side of plasma membrane • basolateral plasma membrane Biological process • transport • water transport • nervous system development • excretion • sensory perception of sound • multicellular organismal water homeostasis • transmembrane transport • renal water absorption • cellular response to interferon-gamma Sources: Amigo / QuickGO
Orthologs
Species	Human	Mouse
Entrez	361	11829
Ensembl	ENSG00000171885	ENSMUSG00000024411
UniProt	P55087	P55088
RefSeq (mRNA)	NM_001650.4	NM_009700.2
RefSeq (protein)	NP_001641.1	NP_033830.2
Location (UCSC)	Chr 18: 24.43 – 24.45 Mb	Chr 18: 15.55 – 15.56 Mb
PubMed search	[1]	[2]

Aquaporin 4 also known as AQP4 is protein which in humans is encoded by the AQP4 gene. AQP4 belongs to the aquaporin family of integral membrane proteins that conduct water through the cell membrane.

Function

AQP4 is constitutively expressed in the basolateral cell membrane of principal collecting duct cells in the kidney and provide a pathway for water to exit these cells.

AQP4 is also expressed in astrocytes and is upregulated by direct insult to the central nervous system.

Pathology

Aquaporin-4 has been proposed as the primary autoimmune target in neuromyelitis optica.

See also

• Aquaporins

Further reading

• Strand L, Moe SE, Solbu TT et al (2009). "Roles of aquaporin-4 isoforms and amino acids in square array assembly". Biochemistry 48 (25): 5785–93. doi:10.1021/bi802231q. PMID 19445480. 
• Goodyear MJ, Crewther SG, Junghans BM (2009). "A role for aquaporin-4 in fluid regulation in the inner retina". Vis. Neurosci. 26 (2): 159–65. doi:10.1017/S0952523809090038. PMID 19366470. 
• Matsushita T, Matsuoka T, Isobe N et al (2009). "Association of the HLA-DPB1*0501 allele with anti-aquaporin-4 antibody positivity in Japanese patients with idiopathic central nervous system demyelinating disorders". Tissue Antigens 73 (2): 171–6. doi:10.1111/j.1399-0039.2008.01172.x. PMID 19140826. 
• Rubino E, Rainero I, Vaula G et al (2009). "Investigating the genetic role of aquaporin4 gene in migraine". The journal of headache and pain 10 (2): 111–4. doi:10.1007/s10194-009-0100-z. PMID 19209385. 
• Benarroch EE (2007). "Aquaporin-4, homeostasis, and neurologic disease". Neurology 69 (24): 2266–8. doi:10.1212/01.wnl.0000286385.59836.e2. PMID 18071147. 
• Ho JD, Yeh R, Sandstrom A et al (2009). "Crystal structure of human aquaporin 4 at 1.8 A and its mechanism of conductance". Proc. Natl. Acad. Sci. U.S.A. 106 (18): 7437–42. doi:10.1073/pnas.0902725106. PMC 2678640. PMID 19383790. http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=2678640. 
• Assereto S, Mastrototaro M, Stringara S et al (2008). "Aquaporin-4 expression is severely reduced in human sarcoglycanopathies and dysferlinopathies". Cell Cycle 7 (14): 2199–207. doi:10.4161/cc.7.14.6272. PMID 18641458. 
• Dibas A, Yang MH, He S et al (2008). "Changes in ocular aquaporin-4 (AQP4) expression following retinal injury". Mol. Vis. 14: 1770–83. PMC 2559817. PMID 18836575. http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=2559817. 
• Sorani MD, Zador Z, Hurowitz E et al (2008). "Novel variants in human Aquaporin-4 reduce cellular water permeability". Hum. Mol. Genet. 17 (15): 2379–89. doi:10.1093/hmg/ddn138. PMC 2733814. PMID 18511455. http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=2733814. 
• Ng WH, Hy JW, Tan WL et al (2009). "Aquaporin-4 expression is increased in edematous meningiomas". Journal of Clinical Neuroscience 16 (3): 441–3. doi:10.1016/j.jocn.2008.04.028. PMID 19153045. 
• Nishiyama S, Ito T, Misu T et al (2009). "A case of NMO seropositive for aquaporin-4 antibody more than 10 years before onset". Neurology 72 (22): 1960–1. doi:10.1212/WNL.0b013e3181a82621. PMID 19487655. 
• Misu T, Fujihara K, Itoyama Y (2008). "[Neuromyelitis optica and anti-aquaporin 4 antibody--an overview]". Brain and nerve = Shinkei kenkyÅ" no shinpo 60 (5): 527–37. PMID 18516975. 
• 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. PMID 9824541. 
• Doi H, Matsushita T, Isobe N et al (2009). "Hypercomplementemia at relapse in patients with anti-aquaporin-4 antibody". Mult. Scler. 15 (3): 304–10. doi:10.1177/1352458508099139. PMID 19028829. 
• Pittock SJ, Lennon VA (2008). "Aquaporin-4 autoantibodies in a paraneoplastic context". Arch. Neurol. 65 (5): 629–32. doi:10.1001/archneur.65.5.629. PMID 18474738. 
• Matsushita T, Isobe N, Matsuoka T et al (2009). "Aquaporin-4 autoimmune syndrome and anti-aquaporin-4 antibody-negative opticospinal multiple sclerosis in Japanese". Mult. Scler. 15 (7): 834–47. doi:10.1177/1352458509104595. PMID 19465451. 
• Graber DJ, Levy M, Kerr D, Wade WF (2008). "Neuromyelitis optica pathogenesis and aquaporin 4". Journal of neuroinflammation 5: 22. doi:10.1186/1742-2094-5-22. PMC 2427020. PMID 18510734. http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=2427020. 
• Baba T, Nakashima I, Kanbayashi T et al (2009). "Narcolepsy as an initial manifestation of neuromyelitis optica with anti-aquaporin-4 antibody". J. Neurol. 256 (2): 287–8. doi:10.1007/s00415-009-0139-4. PMID 19266146. 
• Xu H, Zhang Y, Wei W et al (2009). "Differential expression of aquaporin-4 in human gastric normal and cancer tissues". Gastroenterol. Clin. Biol. 33 (1 Pt 1): 72–6. doi:10.1016/j.gcb.2008.07.010. PMID 19112001. 
• Kadohira I, Abe Y, Nuriya M et al (2008). "Phosphorylation in the C-terminal domain of Aquaporin-4 is required for Golgi transition in primary cultured astrocytes". Biochem. Biophys. Res. Commun. 377 (2): 463–8. doi:10.1016/j.bbrc.2008.09.155. PMID 18854171. 

External links

• MeSH Aquaporin+4