Rearrangement of the heterotrimeric G(s) complex cAMP induces dissociation of inactive PKA tetramers Activated Adenylate cyclase catalyses cAMP synthesis G alpha (s) activates adenylate cyclase PathwayStep2077 PathwayStep2078 PathwayStep2079 PathwayStep2042 Passive Transport of Water out of Cell by Aquaporin-4 Passive Transport of Water out of Cell by Aquaporin-3 Passive Transport of Water out of Cell by Aquaporin-1 Passive Transport of Water into Cell by Aquaporin-2 Phosphorylated on Serine256 Passive Transport of Water into Cell by Aquaporin-1 Translocation of Aquaporin-2 from Intracellular Vesicles to the Apical Plasma Membrane Phosphorylation of Aquaporin-2 by Protein Kinase A (PKA) Exchange of GDP for GTP by AVP:AVPR2:Heterotrimeric G(s) Complex Binding of Inactive Heterotrimeric G(s) Complex by AVP:AVPR2 Complex Vasopressin receptor type 2 bind vasopressin PathwayStep4999 PathwayStep4998 PathwayStep4997 PathwayStep4996 PathwayStep4995 PathwayStep4994 PathwayStep5002 PathwayStep5003 PathwayStep5000 PathwayStep5001 Regulation of Water Balance by Renal Aquaporins Authored: May, B, 2009-08-06 Edited: May, B, 2009-08-11 GENE ONTOLOGYGO:0006833 In the kidney water and solutes are passed out of the bloodstream and into the proximal tubule via the slit-like structure formed by nephrin in the glomerulus. Water is reabsorbed from the filtrate during its transit through the proximal tubule, the descending loop of Henle, the distal convoluted tubule, and the collecting duct.<br>Aquaporin-1 (AQP1) in the proximal tubule and the descending thin limb of Henle is responsible for about 90% of reabsorption (as estimated from mouse knockouts of AQP1). AQP1 is located on both the apical and basolateral surface of epithelial cells and thus transports water through the epithelium and back into the bloodstream.<br>In the collecting duct epithelial cells have AQP2 on their apical surface and AQP3 and AQP4 on their basolateral surface to transport water across the epithelium. The permeability of the epithelium is regulated by vasopressin, which activates the phosphorylation and subsequent translocation of AQP2 from intracellular vesicles to the plasma membrane. Pubmed11773613 Pubmed15924268 Pubmed17222168 Pubmed18566824 Pubmed19096775 Reactome Database ID Release 43432040 Reactome, http://www.reactome.org ReactomeREACT_24023 Reviewed: Beitz, E, 2010-06-24 Reviewed: Calamita, G, 2010-07-15 Reviewed: Mathai, JC, MacIver, B, 2010-07-31