1nqh

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[[Image:1nqh.gif|left|200px]]
[[Image:1nqh.gif|left|200px]]
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{{Structure
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<!--
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|PDB= 1nqh |SIZE=350|CAPTION= <scene name='initialview01'>1nqh</scene>, resolution 3.10&Aring;
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The line below this paragraph, containing "STRUCTURE_1nqh", creates the "Structure Box" on the page.
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|SITE=
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You may change the PDB parameter (which sets the PDB file loaded into the applet)
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|LIGAND= <scene name='pdbligand=C8E:(HYDROXYETHYLOXY)TRI(ETHYLOXY)OCTANE'>C8E</scene>, <scene name='pdbligand=CA:CALCIUM+ION'>CA</scene>, <scene name='pdbligand=CNC:CO-CYANOCOBALAMIN'>CNC</scene>
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or the SCENE parameter (which sets the initial scene displayed when the page is loaded),
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|ACTIVITY=
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or leave the SCENE parameter empty for the default display.
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|GENE= BTUB ([http://www.ncbi.nlm.nih.gov/Taxonomy/Browser/wwwtax.cgi?mode=Info&srchmode=5&id=562 Escherichia coli])
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-->
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|DOMAIN=
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{{STRUCTURE_1nqh| PDB=1nqh | SCENE= }}
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|RELATEDENTRY=[[1nqe|1NQE]], [[1nqf|1NQF]], [[1nqg|1NQG]]
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|RESOURCES=<span class='plainlinks'>[http://oca.weizmann.ac.il/oca-docs/fgij/fg.htm?mol=1nqh FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=1nqh OCA], [http://www.ebi.ac.uk/pdbsum/1nqh PDBsum], [http://www.rcsb.org/pdb/explore.do?structureId=1nqh RCSB]</span>
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}}
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'''OUTER MEMBRANE COBALAMIN TRANSPORTER (BTUB) FROM E. COLI, WITH BOUND CALCIUM AND CYANOCOBALAMIN (VITAMIN B12) SUBSTRATE'''
'''OUTER MEMBRANE COBALAMIN TRANSPORTER (BTUB) FROM E. COLI, WITH BOUND CALCIUM AND CYANOCOBALAMIN (VITAMIN B12) SUBSTRATE'''
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[[Category: Mohanty, A K.]]
[[Category: Mohanty, A K.]]
[[Category: Wiener, M C.]]
[[Category: Wiener, M C.]]
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[[Category: beta barrel]]
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[[Category: Beta barrel]]
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[[Category: calcium binding]]
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[[Category: Calcium binding]]
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[[Category: cobalamin]]
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[[Category: Cobalamin]]
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[[Category: membrane transport]]
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[[Category: Membrane transport]]
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[[Category: vitamin b12]]
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[[Category: Vitamin b12]]
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''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Sat May 3 02:51:32 2008''
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''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Sun Mar 30 22:34:07 2008''
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Revision as of 23:51, 2 May 2008

Image:1nqh.gif

Template:STRUCTURE 1nqh

OUTER MEMBRANE COBALAMIN TRANSPORTER (BTUB) FROM E. COLI, WITH BOUND CALCIUM AND CYANOCOBALAMIN (VITAMIN B12) SUBSTRATE


Overview

The outer membranes of Gram-negative bacteria possess transport proteins essential for uptake of scarce nutrients. In TonB-dependent transporters, a conserved sequence of seven residues, the Ton box, faces the periplasm and interacts with the inner membrane TonB protein to energize an active transport cycle. A critical mechanistic step is the structural change in the Ton box of the transporter upon substrate binding; this essential transmembrane signaling event increases the affinity of the transporter for TonB and enables active transport to proceed. We have solved crystal structures of BtuB, the outer membrane cobalamin transporter from Escherichia coli, in the absence and presence of cyanocobalamin (vitamin B(12)). In these structures, the Ton box is ordered and undergoes a conformational change in the presence of bound substrate. Calcium has been implicated as a necessary factor for the high-affinity binding (K(d) approximately 0.3 nM) of cyanocobalamin to BtuB. We observe two bound calcium ions that order three extracellular loops of BtuB, thus providing a direct (and unusual) structural role for calcium.

About this Structure

1NQH is a Single protein structure of sequence from Escherichia coli. Full crystallographic information is available from OCA.

Reference

Substrate-induced transmembrane signaling in the cobalamin transporter BtuB., Chimento DP, Mohanty AK, Kadner RJ, Wiener MC, Nat Struct Biol. 2003 May;10(5):394-401. PMID:12652322 Page seeded by OCA on Sat May 3 02:51:32 2008

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