1a5y: Difference between revisions

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[[Image:1a5y.gif|left|200px]]
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{{STRUCTURE_1a5y|  PDB=1a5y  |  SCENE=  }}  
{{STRUCTURE_1a5y|  PDB=1a5y  |  SCENE=  }}  


'''PROTEIN TYROSINE PHOSPHATASE 1B CYSTEINYL-PHOSPHATE INTERMEDIATE'''
===PROTEIN TYROSINE PHOSPHATASE 1B CYSTEINYL-PHOSPHATE INTERMEDIATE===




==Overview==
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Protein-tyrosine phosphatases (PTPs) are signal transduction enzymes that catalyze the dephosphorylation of phosphotyrosine residues via the formation of a transient cysteinyl-phosphate intermediate. The mechanism of hydrolysis of this intermediate has been examined by generating a Gln-262 --&gt; Ala mutant of PTP1B, which allows the accumulation and trapping of the intermediate within a PTP1B crystal. The structure of the intermediate at 2.5-A resolution reveals that a conformationally flexible loop (the WPD loop) is closed over the entrance to the catalytic site, sequestering the phosphocysteine intermediate and catalytic site water molecules and preventing nonspecific phosphoryltransfer reactions to extraneous phosphoryl acceptors. One of the catalytic site water molecules, the likely nucleophile, forms a hydrogen bond to the putative catalytic base, Asp-181. In the wild-type enzyme, the nucleophilic water molecule would be coordinated by the side chain of Gln-262. In combination with our previous structural data, we can now visualize each of the reaction steps of the PTP catalytic pathway. The hydrolysis of the cysteinyl-phosphate intermediate of PTPs is reminiscent of GTP hydrolysis by the GTPases, in that both families of enzymes utilize an invariant Gln residue to coordinate the attacking nucleophilic water molecule.
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{{ABSTRACT_PUBMED_9553104}}


==About this Structure==
==About this Structure==
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[[Category: Dephosphorylation]]
[[Category: Dephosphorylation]]
[[Category: Hydrolase]]
[[Category: Hydrolase]]
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Revision as of 16:12, 30 June 2008

File:1a5y.png

Template:STRUCTURE 1a5y

PROTEIN TYROSINE PHOSPHATASE 1B CYSTEINYL-PHOSPHATE INTERMEDIATEPROTEIN TYROSINE PHOSPHATASE 1B CYSTEINYL-PHOSPHATE INTERMEDIATE

Template:ABSTRACT PUBMED 9553104

About this StructureAbout this Structure

1A5Y is a Single protein structure of sequence from Homo sapiens. Full crystallographic information is available from OCA.

ReferenceReference

Visualization of the cysteinyl-phosphate intermediate of a protein-tyrosine phosphatase by x-ray crystallography., Pannifer AD, Flint AJ, Tonks NK, Barford D, J Biol Chem. 1998 Apr 24;273(17):10454-62. PMID:9553104

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