Tyrosine-protein phosphatase non-receptor type 1 also known as protein-tyrosine phosphatase 1B (PTP1B) is an enzyme that is the founding member of the protein tyrosine phosphatase (PTP) family. In humans it is encoded by the PTPN1gene.[5] PTP1B is a negative regulator of the insulin signaling pathway and is considered a promising potential therapeutic target, in particular for treatment of type 2 diabetes.[6] It has also been implicated in the development of breast cancer and has been explored as a potential therapeutic target in that avenue as well.[7][8][9]
The first crystal structure of the PTP1B catalytic domain revealed that the catalytic site exists within a deep cleft of the protein formed by three loops including the WPD loop with the Asp181 residue, a pTyr loop with the Tyr46 residue and a Q loop with the Gln262 residue.[28][29] The pTyr loop and Tyr46 residue are located on the surface of the protein, and thus help to determine the depth a substrate can obtain within the cleft. This acts as a means of driving selectivity, as substrates containing smaller phosphoresidues cannot reach the site of catalytic activity at the base of the cleft.[28] Upon substrate binding, PTP1B undergoes a structural modification in which the WPD loop closes around the substrate, introducing stabilizing pi stacking interactions between the aromatic rings of the phosphotyrosine (pTyr) substrate residue and the Phe182 residue on the WPD loop.[29]
Mechanism
The phosphatase activity of PTP1B occurs via a two-step mechanism.[28] The dephosphorylation of the pTyr substrate occurs in the first step, while the enzyme intermediates are broken down during the second step. During the first step, there is a nucleophilic attack at the phosphocenter by the reduced Cys215 residue, followed by subsequent protonation by Asp181 to yield the neutral tyrosine phenol. The active enzyme is regenerated after the thiophosphate intermediate is hydrolyzed, which is facilitated by the hydrogen bonding interactions of Gln262 and Asp181 that help to position in the water molecule at the desired site of nucleophillic attack.
Regulation
The Cys215 residue is essential for the enzymatic activity of PTP1B and similar cysteine residues are required for the activity of other members of the Class I PTP family.[30] The thiolate anion form is needed for nucleophilic activity but it is susceptible to oxidation by reactive oxygen species (ROS) in the cell which would render the enzyme non-functional. This cysteine residue has been shown to oxidize under increased cellular concentrations of hydrogen peroxide (H2O2), produced in response to EGF and insulin signaling.[31][32][33] The thiolate is oxidized to a sulfenic acid, which is converted to a sulfenyl amide after reacting with the adjacent Ser216 residue.[34] This modification of the Cys215 residue prevents further oxidation of the residue which would be irreversible, and also induces a structural change in the cleft of the active site such that substrates may not bind.[34][35] This oxidation can be reversed through reduction by glutathione and acts as a means of regulating PTP1B activity.[35] Phosphorylation of the Ser50 residue has also been shown as a point of allosteric regulation of PTP1B, in which the phosphorylated state of the enzyme is inactive.[36]
PTP1B has clinical implications in the treatment of type 2 diabetes as well as cancer. Gene knockout studies conducted in murine models has provided substantial evidence for the role PTP1B plays in the regulation of insulin signalling and the development of obesity.[16][17] PTPN1 knockout mice kept on high fat diets showed a resistance to obesity and an increased degree of insulin sensitivity as compared to their wild-type counterparts.[16][17] As such, the design and development of PTP1B inhibitors is a growing field of research for the treatment of type 2 diabetes and obesity.[42]
Although PTP1B is generally studied as a regulator of metabolism, some research suggest it may have a role in tumor development, though whether it is oncogenic or tumor suppressive is unclear, as there is data in support of both arguments. The high ROS concentrations within cancer cells provide an environment for potential constitutive inactivation of PTP1B and it has been shown in two human cancer cell lines HepG2 and A431, that up to 40% of the Cys215 residues in PTP1B can be selectively irreversibly oxidized under these cellular conditions resulting in non-functional PTP1B.[43] In addition, PTPN1 genetic ablation in p53 deficient mice resulted in an increased incidence of lymphomas and a decrease in overall survival rates.[44] In contrast, the PTPN1 gene has been shown to be overexpressed in conjunction with HER2 in breast cancer cases.[8] Murine models of HER2 overexpression in conjunction with PTPN1 knockout resulted in delayed tumor growth and with fewer observed metastases to the lung suggesting that PTPN1 may have an oncogenic role in breast cancer.[8][9]
^Combs AP (March 2010). "Recent advances in the discovery of competitive protein tyrosine phosphatase 1B inhibitors for the treatment of diabetes, obesity, and cancer". J. Med. Chem. 53 (6): 2333–44. doi:10.1021/jm901090b. PMID20000419.
^ abJulien SG, Dubé N, Read M, Penney J, Paquet M, Han Y, Kennedy BP, Muller WJ, Tremblay ML (2007). "Protein tyrosine phosphatase 1B deficiency or inhibition delays ErbB2-induced mammary tumorigenesis and protects from lung metastasis". Nat. Genet. 39 (3): 338–46. doi:10.1038/ng1963. PMID17259984. S2CID33612091.
^Zhu S, Bjorge JD, Fujita DJ (November 2007). "PTP1B contributes to the oncogenic properties of colon cancer cells through Src activation". Cancer Res. 67 (21): 10129–37. doi:10.1158/0008-5472.CAN-06-4338. PMID17974954.
^Sarmiento M, Puius YA, Vetter SW, Keng YF, Wu L, Zhao Y, Lawrence DS, Almo SC, Zhang ZY (July 2000). "Structural basis of plasticity in protein tyrosine phosphatase 1B substrate recognition". Biochemistry. 39 (28): 8171–9. doi:10.1021/bi000319w. PMID10889023.
^Figueiredo H, Figueroa AL, Garcia A, Fernandez-Ruiz R, Broca C, Wojtusciszyn A, et al. (June 2019). "Targeting pancreatic islet PTP1B improves islet graft revascularization and transplant outcomes". Science Translational Medicine. 11 (497): eaar6294. doi:10.1126/scitranslmed.aar6294. hdl:10609/103266. PMID31217339. S2CID195188512.
^Thareja S, Aggarwal S, Bhardwaj TR, Kumar M (2012). "Protein tyrosine phosphatase 1B inhibitors: a molecular level legitimate approach for the management of diabetes mellitus". Med Res Rev. 32 (3): 459–517. doi:10.1002/med.20219. PMID20814956. S2CID23121386.
1a5y: PROTEIN TYROSINE PHOSPHATASE 1B CYSTEINYL-PHOSPHATE INTERMEDIATE
1aax: CRYSTAL STRUCTURE OF PROTEIN TYROSINE PHOSPHATASE 1B COMPLEXED WITH TWO BIS(PARA-PHOSPHOPHENYL)METHANE (BPPM) MOLECULES
1bzc: HUMAN PTP1B CATALYTIC DOMAIN COMPLEXED WITH TPI
1bzh: CYCLIC PEPTIDE INHIBITOR OF HUMAN PTP1B
1bzj: Human ptp1b complexed with tpicooh
1c83: CRYSTAL STRUCTURE OF PROTEIN TYROSINE PHOSPHATASE 1B COMPLEXED WITH 6-(OXALYL-AMINO)-1H-INDOLE-5-CARBOXYLIC ACID
1c84: CRYSTAL STRUCTURE OF PROTEIN TYROSINE PHOSPHATASE 1B COMPLEXED WITH 3-(OXALYL-AMINO)-NAPHTHALENE-2-CARBOXLIC ACID
1c85: CRYSTAL STRUCTURE OF PROTEIN TYROSINE PHOSPHATASE 1B COMPLEXED WITH 2-(OXALYL-AMINO)-BENZOIC ACID
1c86: CRYSTAL STRUCTURE OF PROTEIN TYROSINE PHOSPHATASE 1B (R47V,D48N) COMPLEXED WITH 2-(OXALYL-AMINO-4,7-DIHYDRO-5H-THIENO[2,3-C]PYRAN-3-CARBOXYLIC ACID
1c87: CRYSTAL STRUCTURE OF PROTEIN TYROSINE PHOSPHATASE 1B COMPLEXED WITH 2-(OXALYL-AMINO-4,7-DIHYDRO-5H-THIENO[2,3-C]PYRAN-3-CARBOXYLIC ACID
1c88: CRYSTAL STRUCTURE OF PROTEIN TYROSINE PHOSPHATASE 1B COMPLEXED WITH 2-(OXALYL-AMINO)-4,5,6,7-TETRAHYDRO-THIENO[2,3-C]PYRIDINE-3-CARBOXYLIC ACID
1ecv: CRYSTAL STRUCTURE OF PROTEIN TYROSINE PHOSPHATASE 1B COMPLEXED WITH 5-IODO-2-(OXALYL-AMINO)-BENZOIC ACID
1een: CRYSTAL STRUCTURE OF PROTEIN TYROSINE PHOSPHATASE 1B COMPLEXED WITH ACETYL-D-A-D-BPA-PTYR-L-I-P-Q-Q-G
1eeo: CRYSTAL STRUCTURE OF PROTEIN TYROSINE PHOSPHATASE 1B COMPLEXED WITH ACETYL-E-L-E-F-PTYR-M-D-Y-E-NH2
1g1f: CRYSTAL STRUCTURE OF PROTEIN TYROSINE PHOSPHATASE 1B COMPLEXED WITH A TRI-PHOSPHORYLATED PEPTIDE (RDI(PTR)ETD(PTR)(PTR)RK) FROM THE INSULIN RECEPTOR KINASE
1g1g: CRYSTAL STRUCTURE OF PROTEIN TYROSINE PHOSPHATASE 1B COMPLEXED WITH A MONO-PHOSPHORYLATED PEPTIDE (ETDY(PTR)RKGGKGLL) FROM THE INSULIN RECEPTOR KINASE
1g1h: CRYSTAL STRUCTURE OF PROTEIN TYROSINE PHOSPHATASE 1B COMPLEXED WITH A BIS-PHOSPHORYLATED PEPTIDE (ETD(PTR)(PTR)RKGGKGLL) FROM THE INSULIN RECEPTOR KINASE
1g7f: HUMAN PTP1B CATALYTIC DOMAIN COMPLEXED WITH PNU177496
1g7g: HUMAN PTP1B CATALYTIC DOMAIN COMPLEXES WITH PNU179326
1gfy: RESIDUE 259 IS A KEY DETERMINANT OF SUBSTRATE SPECIFICITY OF PROTEIN-TYROSINE PHOSPHATASE 1B AND ALPHA
1i57: CRYSTAL STRUCTURE OF APO HUMAN PTP1B (C215S) MUTANT
1jf7: HUMAN PTP1B CATALYTIC DOMAIN COMPLEXED WITH PNU177836
1kak: Human Tyrosine Phosphatase 1B Complexed with an Inhibitor
1kav: Human Tyrosine Phosphatase 1B Complexed with an Inhibitor
1l8g: Crystal structure of PTP1B complexed with 7-(1,1-Dioxo-1H-benzo[d]isothiazol-3-yloxymethyl)-2-(oxalyl-amino)-4,7-dihydro-5H-thieno[2,3-c]pyran-3-carboxylic acid
1lqf: Structure of PTP1b in Complex with a Peptidic Bisphosphonate Inhibitor
1nl9: Potent, Selective Protein Tyrosine Phosphatase 1B Inhibitor Compound 12 Using a Linked-Fragment Strategy
1nny: Potent, Selective Protein Tyrosine Phosphatase 1B Inhibitor Compound 23 Using a Linked-Fragment Strategy
1no6: Potent, Selective Protein Tyrosine Phosphatase 1B Inhibitor Compound 5 Using a Linked-Fragment Strategy
1nwe: Ptp1B R47C Modified at C47 with N-[4-(2-{2-[3-(2-Bromo-acetylamino)-propionylamino]-3-hydroxy-propionylamino}-ethyl)-phenyl]-oxalamic acid
1nwl: Crystal structure of the PTP1B complexed with SP7343-SP7964, a pTyr mimetic
1nz7: POTENT, SELECTIVE INHIBITORS OF PROTEIN TYROSINE PHOSPHATASE 1B USING A SECOND PHOSPHOTYROSINE BINDING SITE, complexed with compound 19.
1oem: PTP1B WITH THE CATALYTIC CYSTEINE OXIDIZED TO A SULFENYL-AMIDE BOND
1oeo: PTP1B WITH THE CATALYTIC CYSTEINE OXIDIZED TO SULFONIC ACID
1oes: OXIDATION STATE OF PROTEIN TYROSINE PHOSPHATASE 1B
1oet: OXIDATION STATE OF PROTEIN TYROSINE PHOSPHATASE 1B
1oeu: OXIDATION STATE OF PROTEIN TYROSINE PHOSPHATASE 1B
1oev: OXIDATION STATE OF PROTEIN TYROSINE PHOSPHATASE 1B
1ony: Oxalyl-Aryl-Amino Benzoic Acid inhibitors of PTP1B, compound 17
1onz: Oxalyl-aryl-Amino Benzoic acid Inhibitors of PTP1B, compound 8b
1pa1: Crystal structure of the C215D mutant of protein tyrosine phosphatase 1B
1ph0: Non-carboxylic Acid-Containing Inhibitor of PTP1B Targeting the Second Phosphotyrosine Site
1ptt: CRYSTAL STRUCTURE OF PROTEIN TYROSINE PHOSPHATASE 1B COMPLEXED WITH PHOSPHOTYROSINE-CONTAINING TETRA-PEPTIDE (AC-DEPYL-NH2)
1ptu: CRYSTAL STRUCTURE OF PROTEIN TYROSINE PHOSPHATASE 1B COMPLEXED WITH PHOSPHOTYROSINE-CONTAINING HEXA-PEPTIDE (DADEPYL-NH2)
1ptv: CRYSTAL STRUCTURE OF PROTEIN TYROSINE PHOSPHATASE 1B COMPLEXED WITH PHOSPHOTYROSINE
1pty: CRYSTAL STRUCTURE OF PROTEIN TYROSINE PHOSPHATASE 1B COMPLEXED WITH TWO PHOSPHOTYROSINE MOLECULES
1pxh: Crystal structure of protein tyrosine phosphatase 1B with potent and selective bidentate inhibitor compound 2
1pyn: DUAL-SITE POTENT, SELECTIVE PROTEIN TYROSINE PHOSPHATASE 1B INHIBITOR USING A LINKED FRAGMENT STRATEGY AND A MALONATE HEAD ON THE FIRST SITE
1q1m: A Highly Efficient Approach to a Selective and Cell Active PTP1B inhibitors
1q6j: THE STRUCTURE OF PHOSPHOTYROSINE PHOSPHATASE 1B IN COMPLEX WITH COMPOUND 2
1q6m: THE STRUCTURE OF PHOSPHOTYROSINE PHOSPHATASE 1B IN COMPLEX WITH COMPOUND 3
1q6n: THE STRUCTURE OF PHOSPHOTYROSINE PHOSPHATASE 1B IN COMPLEX WITH COMPOUND 4
1q6p: THE STRUCTURE OF PHOSPHOTYROSINE PHOSPHATASE 1B IN COMPLEX WITH COMPOUND 6
1q6s: THE STRUCTURE OF PHOSPHOTYROSINE PHOSPHATASE 1B IN COMPLEX WITH COMPOUND 9
1q6t: THE STRUCTURE OF PHOSPHOTYROSINE PHOSPHATASE 1B IN COMPLEX WITH COMPOUND 11
1qxk: Monoacid-Based, Cell Permeable, Selective Inhibitors of Protein Tyrosine Phosphatase 1B
1sug: 1.95 A structure of apo protein tyrosine phosphatase 1B
1t48: Allosteric Inhibition of Protein Tyrosine Phosphatase 1B
1t49: Allosteric Inhibition of Protein Tyrosine Phosphatase 1B
1t4j: Allosteric Inhibition of Protein Tyrosine Phosphatase 1B
1wax: PROTEIN TYROSINE PHOSPHATASE 1B WITH ACTIVE SITE INHIBITOR
1xbo: PTP1B complexed with Isoxazole Carboxylic Acid
2azr: Crystal structure of PTP1B with Bicyclic Thiophene inhibitor
2b07: Crystal structure of PTP1B with Tricyclic Thiophene inhibitor.
2b4s: Crystal structure of a complex between PTP1B and the insulin receptor tyrosine kinase
2bgd: STRUCTURE-BASED DESIGN OF PROTEIN TYROSINE PHOSPHATASE-1B INHIBITORS
2bge: STRUCTURE-BASED DESIGN OF PROTEIN TYROSINE PHOSPHATASE-1B INHIBITORS
2cm2: STRUCTURE OF PROTEIN TYROSINE PHOSPHATASE 1B (P212121)
2cm3: STRUCTURE OF PROTEIN TYROSINE PHOSPHATASE 1B (C2)
2cm7: STRUCTURAL BASIS FOR INHIBITION OF PROTEIN TYROSINE PHOSPHATASE 1B BY ISOTHIAZOLIDINONE HETEROCYCLIC PHOSPHONATE MIMETICS
2cm8: STRUCTURAL BASIS FOR INHIBITION OF PROTEIN TYROSINE PHOSPHATASE 1B BY ISOTHIAZOLIDINONE HETEROCYCLIC PHOSPHONATE MIMETICS
2cma: STRUCTURAL BASIS FOR INHIBITION OF PROTEIN TYROSINE PHOSPHATASE 1B BY ISOTHIAZOLIDINONE HETEROCYCLIC PHOSPHONATE MIMETICS
2cmb: STRUCTURAL BASIS FOR INHIBITION OF PROTEIN TYROSINE PHOSPHATASE 1B BY ISOTHIAZOLIDINONE HETEROCYCLIC PHOSPHONATE MIMETICS
2cmc: STRUCTURAL BASIS FOR INHIBITION OF PROTEIN TYROSINE PHOSPHATASE 1B BY ISOTHIAZOLIDINONE HETEROCYCLIC PHOSPHONATE MIMETICS
2cne: STRUCTURAL INSIGHTS INTO THE DESIGN OF NONPEPTIDIC ISOTHIAZOLIDINONE-CONTAINING INHIBITORS OF PROTEIN TYROSINE PHOSPHATASE 1B
2cnf: STRUCTURAL INSIGHTS INTO THE DESIGN OF NONPEPTIDIC ISOTHIAZOLIDINONE-CONTAINING INHIBITORS OF PROTEIN TYROSINE PHOSPHATASE 1B
2cng: STRUCTURAL INSIGHTS INTO THE DESIGN OF NONPEPTIDIC ISOTHIAZOLIDINONE-CONTAINING INHIBITORS OF PROTEIN TYROSINE PHOSPHATASE 1B
2cnh: STRUCTURAL INSIGHTS INTO THE DESIGN OF NONPEPTIDIC ISOTHIAZOLIDINONE-CONTAINING INHIBITORS OF PROTEIN TYROSINE PHOSPHATASE 1B
2cni: STRUCTURAL INSIGHTS INTO THE DESIGN OF NONPEPTIDIC ISOTHIAZOLIDINONE-CONTAINING INHIBITORS OF PROTEIN TYROSINE PHOSPHATASE 1B
2f6f: The structure of the S295F mutant of human PTP1B
2f6t: Protein tyrosine phosphatase 1B with sulfamic acid inhibitors
2f6v: Protein tyrosine phosphatase 1B with sulfamic acid inhibitors
2f6w: Protein tyrosine phosphatase 1B with sulfamic acid inhibitors
2f6y: Protein tyrosine phosphatase 1B with sulfamic acid inhibitors
2f6z: Protein tyrosine phosphatase 1B with sulfamic acid inhibitors
2f70: Protein tyrosine phosphatase 1B with sulfamic acid inhibitors
2f71: Protein tyrosine phosphatase 1B with sulfamic acid inhibitors
2fjm: The structure of phosphotyrosine phosphatase 1B in complex with compound 2
2fjn: The structure of phosphotyrosine phosphatase 1B in complex with compound 2
2h4g: Crystal structure of PTP1B with monocyclic thiophene inhibitor
2h4k: Crystal structure of PTP1B with a monocyclic thiophene inhibitor
2hb1: Crystal Structure of PTP1B with Monocyclic Thiophene Inhibitor
2hnp: CRYSTAL STRUCTURE OF HUMAN PROTEIN TYROSINE PHOSPHATASE 1B
2hnq: CRYSTAL STRUCTURE OF HUMAN PROTEIN TYROSINE PHOSPHATASE 1B
2nt7: Crystal structure of PTP1B-inhibitor complex
2nta: Crystal Structure of PTP1B-inhibitor Complex