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AQP2 is found in the apical cell membranes of the kidney's collecting duct principal cells and in intracellular vesicles located throughout the cell. ==Regulation== It is the only aquaporin regulated by vasopressin. 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.〔Lodish, Harvey F. Molecular Cell Biology. New York: W.H. Freeman, 2008. Print. 445.〕 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. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Aquaporin 2」の詳細全文を読む スポンサード リンク
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