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Liu R, Sun Y, Berthelet J, Bui LC, Xu X, Viguier M, Dupret JM, Deshayes F, Rodrigues Lima F. Biochemical, Enzymatic, and Computational Characterization of Recurrent Somatic Mutations of the Human Protein Tyrosine Phosphatase PTP1B in Primary Mediastinal B Cell Lymphoma. Int J Mol Sci 2022; 23:ijms23137060. [PMID: 35806064 PMCID: PMC9266312 DOI: 10.3390/ijms23137060] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2022] [Revised: 06/23/2022] [Accepted: 06/23/2022] [Indexed: 12/16/2022] Open
Abstract
Human protein tyrosine phosphatase 1B (PTP1B) is a ubiquitous non-receptor tyrosine phosphatase that serves as a major negative regulator of tyrosine phosphorylation cascades of metabolic and oncogenic importance such as the insulin, epidermal growth factor receptor (EGFR), and JAK/STAT pathways. Increasing evidence point to a key role of PTP1B-dependent signaling in cancer. Interestingly, genetic defects in PTP1B have been found in different human malignancies. Notably, recurrent somatic mutations and splice variants of PTP1B were identified in human B cell and Hodgkin lymphomas. In this work, we analyzed the molecular and functional levels of three PTP1B mutations identified in primary mediastinal B cell lymphoma (PMBCL) patients and located in the WPD-loop (V184D), P-loop (R221G), and Q-loop (G259V). Using biochemical, enzymatic, and molecular dynamics approaches, we show that these mutations lead to PTP1B mutants with extremely low intrinsic tyrosine phosphatase activity that display alterations in overall protein stability and in the flexibility of the active site loops of the enzyme. This is in agreement with the key role of the active site loop regions, which are preorganized to interact with the substrate and to enable catalysis. Our study provides molecular and enzymatic evidence for the loss of protein tyrosine phosphatase activity of PTP1B active-site loop mutants identified in human lymphoma.
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Affiliation(s)
- Rongxing Liu
- Université Paris Cité, CNRS, Unité de Biologie Fonctionnelle et Adaptative, F-75013 Paris, France; (R.L.); (L.-C.B.); (M.V.); (J.-M.D.); (F.D.)
| | - Yujie Sun
- School of Medicine and Pharmacy, Ocean University of China, Qingdao 266071, China; (Y.S.); (X.X.)
| | - Jérémy Berthelet
- Université Paris Cité, CNRS, Centre d’Epigénétique et Destin Cellulaire, F-75013 Paris, France;
| | - Linh-Chi Bui
- Université Paris Cité, CNRS, Unité de Biologie Fonctionnelle et Adaptative, F-75013 Paris, France; (R.L.); (L.-C.B.); (M.V.); (J.-M.D.); (F.D.)
| | - Ximing Xu
- School of Medicine and Pharmacy, Ocean University of China, Qingdao 266071, China; (Y.S.); (X.X.)
| | - Mireille Viguier
- Université Paris Cité, CNRS, Unité de Biologie Fonctionnelle et Adaptative, F-75013 Paris, France; (R.L.); (L.-C.B.); (M.V.); (J.-M.D.); (F.D.)
| | - Jean-Marie Dupret
- Université Paris Cité, CNRS, Unité de Biologie Fonctionnelle et Adaptative, F-75013 Paris, France; (R.L.); (L.-C.B.); (M.V.); (J.-M.D.); (F.D.)
| | - Frédérique Deshayes
- Université Paris Cité, CNRS, Unité de Biologie Fonctionnelle et Adaptative, F-75013 Paris, France; (R.L.); (L.-C.B.); (M.V.); (J.-M.D.); (F.D.)
| | - Fernando Rodrigues Lima
- Université Paris Cité, CNRS, Unité de Biologie Fonctionnelle et Adaptative, F-75013 Paris, France; (R.L.); (L.-C.B.); (M.V.); (J.-M.D.); (F.D.)
- Correspondence:
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A Novel PTP1B Inhibitor-Phosphate of Polymannuronic Acid Ameliorates Insulin Resistance by Regulating IRS-1/Akt Signaling. Int J Mol Sci 2021; 22:ijms222312693. [PMID: 34884501 PMCID: PMC8657924 DOI: 10.3390/ijms222312693] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2021] [Revised: 11/21/2021] [Accepted: 11/21/2021] [Indexed: 02/06/2023] Open
Abstract
Protein tyrosine phosphatase 1B (PTP1B) is a critical negative modulator of insulin signaling and has attracted considerable attention in treating type 2 diabetes mellitus (T2DM). Low-molecular-weight polymannuronic acid phosphate (LPMP) was found to be a selective PTP1B inhibitor with an IC50 of 1.02 ± 0.17 μM. Cellular glucose consumption was significantly elevated in insulin-resistant HepG2 cells after LPMP treatment. LPMP could alleviate oxidative stress and endoplasmic reticulum stress, which are associated with the development of insulin resistance. Western blot and polymerase chain reaction (PCR) analysis demonstrated that LPMP could enhance insulin sensitivity through the PTP1B/IRS/Akt transduction pathway. Furthermore, animal study confirmed that LPMP could decrease blood glucose, alleviate insulin resistance, and exert hepatoprotective effects in diabetic mice. Taken together, LPMP can effectively inhibit insulin resistance and has high potential as an anti-diabetic drug candidate to be further developed.
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Lipchock JM, Hendrickson HP, Douglas BB, Bird KE, Ginther PS, Rivalta I, Ten NS, Batista VS, Loria JP. Characterization of Protein Tyrosine Phosphatase 1B Inhibition by Chlorogenic Acid and Cichoric Acid. Biochemistry 2017; 56:96-106. [PMID: 27959494 PMCID: PMC5292209 DOI: 10.1021/acs.biochem.6b01025] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Protein tyrosine phosphatase 1B (PTP1B) is a known regulator of the insulin and leptin signaling pathways and is an active target for the design of inhibitors for the treatment of type II diabetes and obesity. Recently, cichoric acid (CHA) and chlorogenic acid (CGA) were predicted by docking methods to be allosteric inhibitors that bind distal to the active site. However, using a combination of steady-state inhibition kinetics, solution nuclear magnetic resonance experiments, and molecular dynamics simulations, we show that CHA is a competitive inhibitor that binds in the active site of PTP1B. CGA, while a noncompetitive inhibitor, binds in the second aryl phosphate binding site, rather than the predicted benzfuran binding pocket. The molecular dynamics simulations of the apo enzyme and cysteine-phosphoryl intermediate states with and without bound CGA suggest CGA binding inhibits PTP1B by altering hydrogen bonding patterns at the active site. This study provides a mechanistic understanding of the allosteric inhibition of PTP1B.
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Affiliation(s)
- James M. Lipchock
- Department of Chemistry, Washington College, Chestertown, Maryland 21620, United States
| | - Heidi P. Hendrickson
- Department of Chemistry, Yale University, New Haven, Connecticut 06511, United States
| | - Bonnie B. Douglas
- Department of Chemistry, Washington College, Chestertown, Maryland 21620, United States
- Department of Chemistry, Yale University, New Haven, Connecticut 06511, United States
| | - Kelly E. Bird
- Department of Chemistry, Washington College, Chestertown, Maryland 21620, United States
- Department of Chemistry, Yale University, New Haven, Connecticut 06511, United States
| | - Patrick S. Ginther
- Department of Chemistry, Washington College, Chestertown, Maryland 21620, United States
- Department of Chemistry, Yale University, New Haven, Connecticut 06511, United States
| | - Ivan Rivalta
- Department of Chemistry, Yale University, New Haven, Connecticut 06511, United States
- Univ Lyon, Ens de Lyon, CNRS, Université Lyon 1, Laboratoire de Chimie UMR 5182, F-69342, Lyon, France
| | - Nicholas S. Ten
- Department of Chemistry, Yale University, New Haven, Connecticut 06511, United States
| | - Victor S. Batista
- Department of Chemistry, Yale University, New Haven, Connecticut 06511, United States
| | - J. Patrick Loria
- Department of Chemistry, Yale University, New Haven, Connecticut 06511, United States
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, Connecticut 06511, United States
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The insulin-mimetic effect of Morin: a promising molecule in diabetes treatment. Biochim Biophys Acta Gen Subj 2013; 1830:3102-11. [PMID: 23352912 DOI: 10.1016/j.bbagen.2013.01.017] [Citation(s) in RCA: 68] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2012] [Revised: 01/15/2013] [Accepted: 01/17/2013] [Indexed: 11/21/2022]
Abstract
BACKGROUND Type-2 diabetes is a worldwidely diffuse disease characterized by insulin resistance that arises from alterations of receptor and/or post-receptor events of insulin signalling. Studies performed with PTP1B-deficent mice demonstrated that PTP1B is the main negative regulator of insulin signalling. Inhibition or down regulation of this enzyme causes enhanced insulin sensitivity. Hence this enzyme represents the most attractive target for development of innovative anti-diabetic drugs. METHODS Selection of new PTP1B inhibitors among an in house library of polyphenolic compounds was carried out screening their activity. The inhibition mechanism of Morin was determined by kinetic analyses. The cellular action of Morin was assayed on HepG2 cells. Analyses of the insulin signalling pathways was carried out by Western blot methods, glycogen synthesis was estimated by measuring the incorporation of [(3)H]-glucose, gluconeogenesis rate was assayed by measuring the glucose release in the cell medium. Cell growth was estimated by cell count. Docking analysis was conducted with SwissDock program. RESULTS We demonstrated that Morin: i) is a non-competitive inhibitor of PTP1B displaying a Ki in the μM range; ii) increases the phosphorylation of the insulin receptor and Akt; iii) inhibits gluconeogenesis and enhances glycogen synthesis. Morin does not enhance cell growth. CONCLUSIONS We have identified Morin as a new small molecular non-competitive inhibitor of PTP1B, which behaves as an activator and sensitizer of the insulin receptor stimulating the metabolic pathways only. GENERAL SIGNIFICANCE Our study suggests that Morin is a useful lead for development of new low Mr compounds potentially active as antidiabetic drugs.
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Serbielle C, Dupas S, Perdereau E, Héricourt F, Dupuy C, Huguet E, Drezen JM. Evolutionary mechanisms driving the evolution of a large polydnavirus gene family coding for protein tyrosine phosphatases. BMC Evol Biol 2012; 12:253. [PMID: 23270369 PMCID: PMC3573978 DOI: 10.1186/1471-2148-12-253] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2012] [Accepted: 12/11/2012] [Indexed: 11/20/2022] Open
Abstract
Background Gene duplications have been proposed to be the main mechanism involved in genome evolution and in acquisition of new functions. Polydnaviruses (PDVs), symbiotic viruses associated with parasitoid wasps, are ideal model systems to study mechanisms of gene duplications given that PDV genomes consist of virulence genes organized into multigene families. In these systems the viral genome is integrated in a wasp chromosome as a provirus and virus particles containing circular double-stranded DNA are injected into the parasitoids’ hosts and are essential for parasitism success. The viral virulence factors, organized in gene families, are required collectively to induce host immune suppression and developmental arrest. The gene family which encodes protein tyrosine phosphatases (PTPs) has undergone spectacular expansion in several PDV genomes with up to 42 genes. Results Here, we present strong indications that PTP gene family expansion occurred via classical mechanisms: by duplication of large segments of the chromosomally integrated form of the virus sequences (segmental duplication), by tandem duplications within this form and by dispersed duplications. We also propose a novel duplication mechanism specific to PDVs that involves viral circle reintegration into the wasp genome. The PTP copies produced were shown to undergo conservative evolution along with episodes of adaptive evolution. In particular recently produced copies have undergone positive selection in sites most likely involved in defining substrate selectivity. Conclusion The results provide evidence about the dynamic nature of polydnavirus proviral genomes. Classical and PDV-specific duplication mechanisms have been involved in the production of new gene copies. Selection pressures associated with antagonistic interactions with parasitized hosts have shaped these genes used to manipulate lepidopteran physiology with evidence for positive selection involved in adaptation to host targets.
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Affiliation(s)
- Céline Serbielle
- Institut de Recherche sur la Biologie de l'Insecte, UMR CNRS 7261, Faculté des Sciences et Techniques, Université F. Rabelais, Parc de Grandmont, 37200, Tours, France
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Madsen JJ, Linderoth L, Subramanian AK, Andresen TL, Peters GH. Secretory phospholipase A2 activity toward diverse substrates. J Phys Chem B 2011; 115:6853-61. [PMID: 21561115 DOI: 10.1021/jp112137b] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
We have studied secretory phospholipase A(2)-IIA (sPLA(2)) activity toward different phospholipid analogues by performing biophysical characterizations and molecular dynamics simulations. The phospholipids were natural substrates, triple alkyl phospholipids, a prodrug anticancer etherlipid, and an inverted ester. The latter were included to study head group-enzyme interactions. Our simulation results show that the lipids are optimally placed into the binding cleft and that water molecules can freely reach the active site through a well-defined pathway; both are indicative that these substrates are efficiently hydrolyzed, which is in good agreement with our experimental data. The phospholipid analogue with three alkyl side chains forms aggregates of different shapes with no well-defined sizes due to its cone-shape structure. Phosphatidylglycerol and phosphatidylcholine head groups interact with specific charged residues, but relatively large fluctuations are observed, suggesting that these interactions are not necessarily important for stabilizing substrate binding to the enzyme.
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Affiliation(s)
- Jesper J Madsen
- Department of Chemistry, Technical University of Denmark, Kgs. Lyngby, Denmark
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Olmez EO, Alakent B. Alpha7 Helix Plays an Important Role in the Conformational Stability of PTP1B. J Biomol Struct Dyn 2011; 28:675-93. [DOI: 10.1080/07391102.2011.10508599] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
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8
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Peters GH. The effect of Asp54 phosphorylation on the energetics and dynamics in the response regulator protein Spo0F studied by molecular dynamics. Proteins 2009; 75:648-58. [PMID: 19004019 DOI: 10.1002/prot.22276] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
The response regulator protein Spo0F acts as an intermediate phospho-messenger in the signal transduction pathway that controls initiation of the differentiation process of sporculation in the bacterium Bacillus subtilis. The regulatory domain of Spo0F contains a triad of three conserved aspartate residues, whereof one aspartate (Asp54) is phosphorylated. Using molecular dynamics simulations, we have studied the changes in flexibility induced by phosphorylation and estimated the free energy cost of introducing a phosphate group at this position using alchemical free energy calculations. The deduced conformational flexibility compares well with experimental NMR results. We find that the apo-conformation of the protein explores a rough energy landscape resulting in a broad population of conformational substates. Phosphorylation of Spo0F reduces protein flexibility, and in particular, the so-called anchor and recognition regions exhibit lower mobility relative to the apo-conformation. Phosphorylation of Asp54 (P-Asp54), in which the apo-structure coordinates to the magnesium ion, results in extension of the sidechain, and depending on which carboxylate oxygen is phosphorylated, distinct interactions between P-Asp54 and magnesium ion as well as residues in its proximity are established. However, phosphorylation does not affect the coordination number of the magnesium ion yielding, within the statistical uncertainties, the same free energy change.
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Affiliation(s)
- Günther H Peters
- Department of Chemistry, MEMPHYS-Center for Biomembrane Physics, Technical University of Denmark, Kgs Lyngby, Denmark.
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Linderoth L, Andresen TL, Jørgensen K, Madsen R, Peters GH. Molecular basis of phospholipase A2 activity toward phospholipids with sn-1 substitutions. Biophys J 2007; 94:14-26. [PMID: 17827229 PMCID: PMC2134884 DOI: 10.1529/biophysj.107.110106] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
We studied secretory phospholipase A(2) type IIA (sPLA(2)) activity toward phospholipids that are derivatized in the sn-1 position of the glycerol backbone. We explored what type of side group (small versus bulky groups, hydrophobic versus polar groups) can be introduced at the sn-1 position of the glycerol backbone of glycerophospholipids and at the same time be hydrolyzed by sPLA(2). The biophysical characterization revealed that the modified phospholipids can form multilamellar vesicles, and several of the synthesized sn-1 functionalized phospholipids were hydrolyzed by sPLA(2). Molecular dynamics simulations provided detailed insight on an atomic level that can explain the observed sPLA(2) activity toward the different phospholipid analogs. The simulations revealed that, depending on the nature of the side chain located at the sn-1 position, the group may interfere with an incoming water molecule that acts as the nucleophile in the enzymatic reaction. The simulation results are in agreement with the experimentally observed sPLA(2) activity toward the different phospholipid analogs.
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Affiliation(s)
- Lars Linderoth
- Department of Chemistry, Technical University of Denmark, Kgs. Lyngby, Denmark
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10
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Peters GH, Møller MS, Jørgensen K, Rönnholm P, Mikkelsen M, Andresen TL. Secretory phospholipase A2 hydrolysis of phospholipid analogues is dependent on water accessibility to the active site. J Am Chem Soc 2007; 129:5451-61. [PMID: 17419625 DOI: 10.1021/ja067755b] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
A new and unnatural type of phospholipids with the head group attached to the 2-position of the glycerol backbone has been synthesized and shown to be a good substrate for secretory phospholipase A2 (sPLA2). To investigate the unexpected sPLA2 activity, we have compared three different phospholipids by using fluorescence techniques and HPLC, namely: (R)-1,2-dipalmitoyl-glycero-3-phosphocholine (hereafter referred to as 1R), (R)-1-O-hexadecyl-2-palmitoyl-glycero-3-phoshocholine (2R), and (S)-1-O-hexadecyl-3-palmitoyl-glycero-2-phosphocholine (3S). Furthermore, to understand the underlying mechanisms for the observed differences, we have performed molecular dynamics simulations to clarify on a structural level the substrate specificity of sPLA2 toward phospholipid analogues with their head groups in the 2-position of the glycerol backbone. We have studied the lipids above 1R, 2R, and 3S as well as their enantiomers 1S, 2S, and 3R. In the simulations of sPLA2-1S and sPLA2-3R, structural distortion in the binding cleft induced by the phospholipids showed that these are not substrates for sPLA2. In the case of the phospholipids 1R, 2R, and 3S, our simulations revealed that the difference observed experimentally in sPLA2 activity might be caused by reduced access of water molecules to the active site. We have monitored the number of water molecules that enter the active site region for the different sPLA2-phospholipid complexes and found that the probability of a water molecule reaching the correct position such that hydrolysis can occur is reduced for the unnatural lipids. The relative water count follows 1R > 2R > 3S. This is in good agreement with experimental data that indicate the same trend for sPLA2 activity: 1R > 2R > 3S.
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Affiliation(s)
- Günther H Peters
- Department of Chemistry, MEMPHYS-Center for Biomembrane Physics, Technical University of Denmark, DK-2800 Lyngby, Denmark
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11
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Groen A, Lemeer S, van der Wijk T, Overvoorde J, Heck AJR, Ostman A, Barford D, Slijper M, den Hertog J. Differential Oxidation of Protein-tyrosine Phosphatases. J Biol Chem 2005; 280:10298-304. [PMID: 15623519 DOI: 10.1074/jbc.m412424200] [Citation(s) in RCA: 105] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Oxidation is emerging as an important regulatory mechanism of protein-tyrosine phosphatases (PTPs). Here we report that PTPs are differentially oxidized, and we provide evidence for the underlying mechanism. The membrane-proximal RPTPalpha-D1 was catalytically active but not readily oxidized as assessed by immunoprobing with an antibody that recognized oxidized catalytic site cysteines in PTPs (oxPTPs). In contrast, the membrane-distal RPTPalpha-D2, a poor PTP, was readily oxidized. Oxidized catalytic site cysteines in PTP immunoprobing and mass spectrometry demonstrated that mutation of two residues in the Tyr(P) loop and the WPD loop that reverse catalytic activity of RPTPalpha-D1 and RPTPalpha-D2 also reversed oxidizability, suggesting that oxidizability and catalytic activity are coupled. However, catalytically active PTP1B and LAR-D1 were readily oxidized. Oxidizability was strongly dependent on pH, indicating that the microenvironment of the catalytic cysteine has an important role. Crystal structures of PTP domains demonstrated that the orientation of the absolutely conserved PTP loop arginine correlates with oxidizability of PTPs, and consistently, RPTPmu-D1, with a similar conformation as RPTPalpha-D1, was not readily oxidized. In conclusion, PTPs are differentially oxidized at physiological pH and H(2)O(2) concentrations, and the PTP loop arginine is an important determinant for susceptibility to oxidation.
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Affiliation(s)
- Arnoud Groen
- Hubrecht Laboratory, Netherlands Institute for Developmental Biology, Uppsalalaan 8, 3584 CT Utrecht, The Netherlands
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12
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Villa F, Deak M, Bloomberg GB, Alessi DR, van Aalten DMF. Crystal structure of the PTPL1/FAP-1 human tyrosine phosphatase mutated in colorectal cancer: evidence for a second phosphotyrosine substrate recognition pocket. J Biol Chem 2004; 280:8180-7. [PMID: 15611135 DOI: 10.1074/jbc.m412211200] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Protein-tyrosine phosphatase-L1 (PTPL1, also known as FAP-1, PTP1E, PTP-BAS, and PTPN13) is mutated in a significant number of colorectal tumors and may play a role in down-regulating signaling responses mediated by phosphatidylinositol 3-kinase, although the precise substrates are as yet unknown. In this study, we describe a 1.8 A resolution crystal structure of a fully active fragment of PTPL1 encompassing the catalytic domain. PTPL1 adopts the standard PTP fold, albeit with an unusually positioned additional N-terminal helix, and shows an ordered phosphate in the active site. Interestingly, a positively charged pocket is located near the PTPL1 catalytic site, reminiscent of the second phosphotyrosine binding site in PTP1B, which is required to dephosphorylate peptides containing two adjacent phosphotyrosine residues (as occurs for example in the activated insulin receptor). We demonstrate that PTPL1, like PTP1B, interacts with and dephosphorylates a bis-phosphorylated insulin receptor peptide more efficiently than monophosphorylated peptides, indicating that PTPL1 may down-regulate the phosphatidylinositol 3-kinase pathway, by dephosphorylating insulin or growth factor receptors that contain tandem phosphotyrosines. The structure also reveals that four out of five PTPL1 mutations found in colorectal cancers are located on solvent-exposed regions remote from the active site, consistent with these mutants being normally active. In contrast, the fifth mutation, which changes Met-2307 to Thr, is close to the active site cysteine and decreases activity significantly. Our studies provide the first molecular description of the PTPL1 catalytic domain and give new insight into the function of PTPL1.
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MESH Headings
- Amino Acid Sequence
- Binding Sites
- Catalytic Domain
- Cloning, Molecular
- Colorectal Neoplasms/genetics
- Crystallography, X-Ray
- DNA/chemistry
- DNA, Complementary/metabolism
- Dose-Response Relationship, Drug
- Down-Regulation
- Humans
- Kinetics
- Models, Molecular
- Molecular Sequence Data
- Mutagenesis, Site-Directed
- Mutation
- Peptides/chemistry
- Phosphatidylinositol 3-Kinases/metabolism
- Phosphorylation
- Phosphotyrosine/chemistry
- Protein Binding
- Protein Folding
- Protein Structure, Secondary
- Protein Structure, Tertiary
- Protein Tyrosine Phosphatase, Non-Receptor Type 13
- Protein Tyrosine Phosphatases/chemistry
- Receptor, Insulin/chemistry
- Signal Transduction
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Affiliation(s)
- Fabrizio Villa
- Division of Biological Chemistry and Molecular Microbiology, School of Life Sciences, University of Dundee, DD1 5EH, Scotland
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