The exchange of functional domains among aquaporins with different transport characteristics
| Autor: | Terlouw Sa, Peter M.T. Deen, van der Kemp Aj, Mulders Sm, van Boxtel Ha, van Os Ch |
|---|---|
| Rok vydání: | 1998 |
| Předmět: |
Physiology
Protein Conformation Clinical Biochemistry Xenopus Aquaporin Biology urologic and male genital diseases Aquaporins Xenopus laevis Protein structure Physiology (medical) Animals Protein Isoforms Receptor Chromatography urogenital system Biological Transport biology.organism_classification Transmembrane protein Rats Membrane Aquaporin 2 Permeability (electromagnetism) Biophysics Oocytes Cattle |
| Zdroj: | Pflugers Archiv : European journal of physiology. 436(4) |
| ISSN: | 1432-2013 |
| Popis: | Aquaporins are transmembrane proteins that contain six bilayer-spanning domains, connected by loops A to E. The hourglass model predicts that the conserved loops B and E are essential for the formation of the water pore. To test the importance of loops B and E in the determination of the transport characteristics, we exchanged loops B and/or E between AQP0, AQP2, and AQP3. Detailed functional, immunoblot and immunocytochemical analyses of expression in Xenopus oocytes revealed that six out of the nine chimeric aquaporin proteins were not functional, because of misrouting. AQP0 with loop E of AQP2 was not impaired in its routing and revealed a low water permeability equal to that of wild-type AQP0. AQP2 with loop B of AQP0 was also routed normally and gave a high water permeability, similar to that of wild-type AQP2. AQP0 with loops B and E of AQP2 (AQP0–2BE) did not result in an increase in water permeability and was partly misrouted. However, the plasma membrane expression was high enough to expect an increase in water permeability, as loops B and E of AQP2 confer AQP2’s water permeability to AQP0. Although it is unclear for the dual chimera (AQP0–2BE), the parental water permeabilities obtained in oocytes expressing AQP0 with loop E of AQP2 or AQP2 with loop B of AQP0 indicate that, besides loops B and E, other parts of the AQP protein are important in the determination of the characteristics of the channel. |
| Databáze: | OpenAIRE |
| Externí odkaz: |
|
Full text from SpringerLink