Urea transporter
Crystal Structure of the Urea Transporter from Desulfovibrio VulgarisCrystal Structure of the Urea Transporter from Desulfovibrio Vulgaris
Urea is highly concentrated in the mammalian kidney to produce the osmotic gradient necessary for water re-absorption. Free diffusion of urea across cell membranes is slow owing to its high polarity, and specialized urea transporters have evolved to achieve rapid and selective urea permeation. Here we present the 2.3 A structure of a functional urea transporter from the bacterium Desulfovibrio vulgaris. The transporter is a homotrimer, and each subunit contains a continuous membrane-spanning pore formed by the two homologous halves of the protein. The pore contains a constricted selectivity filter that can accommodate several dehydrated urea molecules in single file. Backbone and side-chain oxygen atoms provide continuous coordination of urea as it progresses through the filter, and well-placed alpha-helix dipoles provide further compensation for dehydration energy. These results establish that the urea transporter operates by a channel-like mechanism and reveal the physical and chemical basis of urea selectivity.
Crystal structure of a bacterial homologue of the kidney urea transporter., Levin EJ, Quick M, Zhou M, Nature. 2009 Dec 10;462(7274):757-61. Epub . PMID:19865084
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.
About this StructureAbout this Structure
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| urea transporter complex with gold ions (3k3f), resolution 2.30Å () | |||||||
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| Resources: | FirstGlance, OCA, PDBsum, RCSB | ||||||
| Coordinates: | save as pdb, mmCIF, xml | ||||||
The structure revealed in the asymmetric unit.
However, the urea transporter crystallized as , and this is seen when considering the crystallographic three-fold symmetry axis.
To help give a better idea of how the urea transporter is oriented in the membrane lipid bilayer, as calculated by the Orientations of Proteins in Membranes database(University of Michigan, USA) is shown with the red patch of spheres indicating the boundary of the hydrophobic core closet to the outside of the cell and the dark blue patch of spheres indicating the boundary closest to the inside of the cell.
PDB entryPDB entry
3k3f is a 1 chain structure with sequence from Desulfovibrio vulgaris str. hildenborough. Full crystallographic information is available from OCA.
Reference for the structureReference for the structure
- ↑ Levin EJ, Quick M, Zhou M. Crystal structure of a bacterial homologue of the kidney urea transporter. Nature. 2009 Dec 10;462(7274):757-61. Epub . PMID:19865084 doi:10.1038/nature08558
See AlsoSee Also
- ↑ Knepper MA, Mindell JA. Structural biology: Molecular coin slots for urea. Nature. 2009 Dec 10;462(7274):733-4. PMID:20010678 doi:10.1038/462733a
- For Additional Information, See Membrane Channels & Pumps
ReferenceReference
Page started with original page on 3k3f seeded by OCA on Thu Jan 28 14:58:46 2010