@article {45967,
	title = {Noncanonical binding of calmodulin to aquaporin-0: implications for channel regulation.},
	journal = {Structure},
	volume = {16},
	year = {2008},
	month = {2008 Sep 10},
	pages = {1389-98},
	abstract = {<p>Aquaporins (AQPs) are a family of ubiquitous membrane channels that conduct water across cell membranes. AQPs form homotetramers containing four functional and independent water pores. Aquaporin-0 (AQP0) is expressed in the eye lens, where its water permeability is regulated by calmodulin (CaM). Here we use a combination of biochemical methods and NMR spectroscopy to probe the interaction between AQP0 and CaM. We show that CaM binds the AQP0 C-terminal domain in a calcium-dependent manner. We demonstrate that only two CaM molecules bind a single AQP0 tetramer in a noncanonical fashion, suggesting a form of cooperativity between AQP0 monomers. Based on these results, we derive a structural model of the AQP0/CaM complex, which suggests CaM may be inhibitory to channel permeability by capping the vestibules of two monomers within the AQP0 tetramer. Finally, phosphorylation within AQP0{\textquoteright}s CaM binding domain inhibits the AQP0/CaM interaction, suggesting a temporal regulatory mechanism for complex formation.</p>
},
	keywords = {Amino Acid Sequence, Animals, Aquaporins, Calcium, Calmodulin, Crystallins, Eye Proteins, Ion Channels, Models, Molecular, Molecular Sequence Data, Phosphorylation, Protein Binding, Protein Structure, Quaternary, Protein Structure, Secondary, Protein Structure, Tertiary, Protein-Serine-Threonine Kinases, Sequence Homology, Amino Acid, Sheep},
	issn = {0969-2126},
	doi = {10.1016/j.str.2008.06.011},
	author = {Reichow, Steve L and Gonen, Tamir}
}
