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1ltt

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[[Image:1ltt.jpg|left|200px]]
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[[Image:1ltt.png|left|200px]]
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==Overview==
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{{ABSTRACT_1741035}}
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Recognition of the oligosaccharide portion of ganglioside GM1 in membranes of target cells by the heat-labile enterotoxin from Escherichia coli is the crucial first step in its pathogenesis, as it is for the closely related cholera toxin. These toxins have five B subunits, which are essential for GM1 binding, and a single A subunit, which needs to be nicked by proteolysis and reduced, yielding an A1-'enzyme' and an A2-'linker' peptide. A1 is translocated across the membrane of intestinal epithelial cells, possibly after endocytosis, upon which it ADP-ribosylates the G protein Gs alpha. The mechanism of binding and translocation of these toxins has been extensively investigated, but how the protein is orientated on binding is still not clear. Knowing the precise arrangement of the ganglioside binding sites of the toxins will be useful for designing drugs against the diarrhoeal diseases caused by organisms secreting these toxins and in the development of oral vaccines against them. We present here the three-dimensional structure of the E. coli heat-labile enterotoxin complexed with lactose. This reveals the location of the binding site of the terminal galactose of GM1, which is consistent with toxin binding to the target cell with its A1 fragment pointing away from the membrane. A small helix is identified at the carboxy terminus of A2 which emerges through the central pore of the B subunits and probably comes into contact with the membrane upon binding, whereas the A1 subunit is flexible with respect to the B pentamer.
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==About this Structure==
==About this Structure==
1LTT is a [[Protein complex]] structure of sequences from [http://en.wikipedia.org/wiki/Escherichia_coli Escherichia coli]. The following page contains interesting information on the relation of 1LTT with [[http://pdb.rcsb.org/pdb/static.do?p=education_discussion/molecule_of_the_month/pdb69_1.html Cholera Toxin]]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1LTT OCA].
1LTT is a [[Protein complex]] structure of sequences from [http://en.wikipedia.org/wiki/Escherichia_coli Escherichia coli]. The following page contains interesting information on the relation of 1LTT with [[http://pdb.rcsb.org/pdb/static.do?p=education_discussion/molecule_of_the_month/pdb69_1.html Cholera Toxin]]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1LTT OCA].
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==Reference==
 
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Lactose binding to heat-labile enterotoxin revealed by X-ray crystallography., Sixma TK, Pronk SE, Kalk KH, van Zanten BA, Berghuis AM, Hol WG, Nature. 1992 Feb 6;355(6360):561-4. PMID:[http://www.ncbi.nlm.nih.gov/pubmed/1741035 1741035]
 
[[Category: Cholera Toxin]]
[[Category: Cholera Toxin]]
[[Category: Escherichia coli]]
[[Category: Escherichia coli]]
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[[Category: Sixma, T K.]]
[[Category: Sixma, T K.]]
[[Category: Toxin]]
[[Category: Toxin]]
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''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Sat May 3 00:16:48 2008''
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''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Thu Jun 26 17:41:38 2008''

Revision as of 14:41, 26 June 2008

Image:1ltt.png

Template:STRUCTURE 1ltt

LACTOSE BINDING TO HEAT-LABILE ENTEROTOXIN REVEALED BY X-RAY CRYSTALLOGRAPHY


Template:ABSTRACT 1741035

About this Structure

1LTT is a Protein complex structure of sequences from Escherichia coli. The following page contains interesting information on the relation of 1LTT with [Cholera Toxin]. Full crystallographic information is available from OCA.

Page seeded by OCA on Thu Jun 26 17:41:38 2008

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