1a5y
PROTEIN TYROSINE PHOSPHATASE 1B CYSTEINYL-PHOSPHATE INTERMEDIATE
Structural highlights
FunctionPTN1_HUMAN Tyrosine-protein phosphatase which acts as a regulator of endoplasmic reticulum unfolded protein response. Mediates dephosphorylation of EIF2AK3/PERK; inactivating the protein kinase activity of EIF2AK3/PERK. May play an important role in CKII- and p60c-src-induced signal transduction cascades. May regulate the EFNA5-EPHA3 signaling pathway which modulates cell reorganization and cell-cell repulsion.[1] [2] Evolutionary Conservation Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf. Publication Abstract from PubMedProtein-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 --> 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. 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[3] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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