期刊
BIOLOGY OF THE CELL
卷 98, 期 2, 页码 101-109出版社
WILEY
DOI: 10.1042/BC20050025
关键词
aquaporin; haemagglutinin (HA); H+-ATPase; intracellular vesicle; sorting signal
类别
资金
- NEI NIH HHS [EY11239] Funding Source: Medline
- NHLBI NIH HHS [HL48268, HL33991] Funding Source: Medline
- NIDDK NIH HHS [DK065098, DK32753] Funding Source: Medline
Background information. Most AQPs (aquaporins) function at the plasma membrane, however AQP6 is exclusively localized to membranes of intracellular vesicles in acid-secreting type-A intercalated cells of renal collecting ducts. The intracellular distribution indicates that AQP6 has a function distinct from trans-epithelial water movement. Results. We show by mutational analyses and immunofluorescence that the N-terminus of AQP6 is a determinant for its intracellular localization. Presence or absence at the plasma membrane of AQP6 constructs was confirmed by electrophysiological methods. Addition of a GFP (green fluorescent protein) or a HA (haemagglutinin) epitope tag (GFP-AQP6 or HA-AQP6) to the N-terminus of AQP6, directed AQP6 to the plasma membranes of transfected Madin-Darby canine kidney cells. In contrast, addition of a GFP tag to the C-terminus (AQP6-GFP) caused the protein to remain intracellular, similar to untagged wild-type AQP6. Replacement of the N-terminus of AQP6 by that of AQP1 also directed AQP6 to the plasma membranes, whereas the N-terminus of AQP6 retained AQP1 in cytosolic sites. Conclusion. Our results suggest that the N-terminus of AQP6 is critical for trafficking of the protein to the intracellular sites. Moreover, our studies provide an approach for future identification of proteins involved in vesicle sorting in the acid-secreting type-A intercalated cells.
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