Structural highlights
Function
AQP4_RAT Forms a water-specific channel. Osmoreceptor which regulates body water balance and mediates water flow within the central nervous system. It is expressed predominantly in the ependymal cell lining the aqueductal system and over the space of the brain in contact with the subarachnoid space, as cerebrospinal fluid fills these structures it may facilitate water balance between brain parenchyma and the fluid compartment. In the plasma membranes of the neurons of the paraventricular and supraoptic nuclei, it may mediate rapid changes in cell volume in response to local shifts in extracellular osmolarity.
Evolutionary Conservation
Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf.
Publication Abstract from PubMed
Aquaporin-4 (AQP4) is the predominant water channel in the mammalian brain and an important drug target for treatment of cerebral edema, bipolar disorder and mesial temporal lobe epilepsy. We determined the AQP4 structure by electron crystallography of double-layered, two-dimensional (2D) crystals. The structure allows us to discuss how the expression ratio between the long and short AQP4 splicing variant can determine the size of in vivo orthogonal arrays. Furthermore, AQP4 contains a short 3(10) helix in an extracellular loop, which mediates weak but specific interactions between AQP4 molecules in adjoining membranes. This finding suggests a previously unexpected role for AQP4 in cell adhesion. This notion was corroborated by expression of AQP4 in L-cells, which resulted in clustering of the cells. Our AQP4 structure thus enables us to propose models for the size regulation of orthogonal arrays and channel-mediated cell adhesion.
Implications of the aquaporin-4 structure on array formation and cell adhesion.,Hiroaki Y, Tani K, Kamegawa A, Gyobu N, Nishikawa K, Suzuki H, Walz T, Sasaki S, Mitsuoka K, Kimura K, Mizoguchi A, Fujiyoshi Y J Mol Biol. 2006 Jan 27;355(4):628-39. Epub 2005 Nov 17. PMID:16325200[1]
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.
See Also
References
- ↑ Hiroaki Y, Tani K, Kamegawa A, Gyobu N, Nishikawa K, Suzuki H, Walz T, Sasaki S, Mitsuoka K, Kimura K, Mizoguchi A, Fujiyoshi Y. Implications of the aquaporin-4 structure on array formation and cell adhesion. J Mol Biol. 2006 Jan 27;355(4):628-39. Epub 2005 Nov 17. PMID:16325200 doi:10.1016/j.jmb.2005.10.081
