Aquaporin water channels facilitate the bi-directional flow of water and small, neutral solutes down an osmotic gradient in all kingdoms of life. Over the last two decades, the availability of high-quality protein has underpinned progress in the structural and functional characterization of these water channels. In particular, recombinant protein technology has guaranteed the supply of aquaporin samples that were of sufficient quality and quantity for further study. Here we review the features of successful expression, purification and characterization strategies that have underpinned these successes and that will drive further breakthroughs in the field. Overall, Escherichia coli is a suitable host for prokaryotic isoforms, while Pichia pastoris is the most commonly-used recombinant host for eukaryotic variants. Generally, a two-step purification procedure is suitable after solubilization in glucopyranosides and most structures are determined by X-ray following crystallization.
Bibliographical note© 2021, Elsevier. Licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International http://creativecommons.org/licenses/by-nc-nd/4.0/
Funding: The work presented in this study was supported by research grants from the Swedish research Council; VR-M, Structural studies of aquaporin:protein complexes as well as VR-RÅC (2017-06727), and the Swedish Brain Foundation (FO2018-0231) to Kristina Hedfalk and from the Biotechnology & Biological Sciences Research Council (through BB/P025927/1) to Roslyn M. Bill.
- Recombinant production
- Water channel