
<ArticleTitle>Large-scale purification of functional recombinant human <prot>aquaporin-2</prot>.</ArticleTitle>
<AbstractText>The homotetrameric <prot>aquaporin-2</prot> (<prot>AQP2</prot>) water channel is essential for the concentration of urine and of critical importance in diseases with water dysregulation, such as nephrogenic diabetes insipidus, congestive heart failure, liver cirrhosis and pre-eclampsia. The structure of human <prot>AQP2</prot> is a prerequisite for understanding its function and for designing specific blockers. To obtain sufficient amounts of <prot>AQP2</prot> for structural analyses, we have expressed recombinant his-tagged human <prot>AQP2</prot> (HT-<prot>AQP2</prot>) in the baculovirus/insect cell system. Using the protocols outlined in this study, 0.5 mg of pure HT-<prot>AQP2</prot> could be obtained per liter of bioreactor culture. HT-<prot>AQP2</prot> had retained its homotetrameric structure and exhibited a single channel water permeability of 0.93+/-0.03x10(-13) cm3/s, similar to that of other AQPs. Thus, the baculovirus/insect cell system allows large-scale expression of functional recombinant human <prot>AQP2</prot> that is suitable for structural studies.</AbstractText>
