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PLoS Biol. 2003 Dec;1(3):E72. Epub 2003 Dec 22.

Architecture and selectivity in aquaporins: 2.5 a X-ray structure of aquaporin Z.

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Department of Biochemistry and Biophysics, University of California School of Medicine, San Francisco, California, USA.


Aquaporins are a family of water and small molecule channels found in organisms ranging from bacteria to animals. One of these channels, the E. coli protein aquaporin Z (AqpZ), has been shown to selectively conduct only water at high rates. We have expressed, purified, crystallized, and solved the X-ray structure of AqpZ. The 2.5 A resolution structure of AqpZ suggests aquaporin selectivity results both from a steric mechanism due to pore size and from specific amino acid substitutions that regulate the preference for a hydrophobic or hydrophilic substrate. This structure provides direct evidence on the molecular mechanisms of specificity between water and glycerol in this family of channels from a single species. It is to our knowledge the first atomic resolution structure of a recombinant aquaporin and so provides a platform for combined genetic, mutational, functional, and structural determinations of the mechanisms of aquaporins and, more generally, the assembly of multimeric membrane proteins.

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Conflict of interest statement

The authors have declared that no conflicts of interest exist.

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