scholarly journals Functional Association between the Insulin Receptor and the Transmembrane Protein-tyrosine Phosphatase LAR in Intact Cells

1997 ◽  
Vol 272 (1) ◽  
pp. 448-457 ◽  
Author(s):  
Faiyaz Ahmad ◽  
Barry J. Goldstein
2020 ◽  
Vol 20 (29) ◽  
pp. 2692-2707
Author(s):  
Sisir Nandi ◽  
Mridula Saxena

Background: There has been growing interest in the development of highly potent and selective protein tyrosine phosphatase (PTP1B) inhibitors for the past 2-3 decades. Though most PTPs share a common active site motif, the interest in selective inhibitors, particularly against PTP1B is increasing to discover new chemical entities as antidiabetic agents. In the current paradigm to find potent and selective PTP1B inhibitors, which is currently considered as one of the best validated biological targets for non-insulin-dependent diabetic and obese individuals, resistance to insulin due to decreased sensitivity of the insulin receptor is a pathological factor and is also genetically linked, causing type II diabetes. Objectives: Insulin receptor sensitization is performed by a signal transduction mechanism via a selective protein tyrosine phosphatase (PTP1B). After the interaction of insulin with its receptor, autophosphorylation of the intracellular part of the receptor takes place, turning it into an active kinase (sensitization). PTP1B is involved in the desensitization of the receptor by dephosphorylation. PTP1b inhibitors delay the receptor desensitization, prolonging insulin effect and making PTP1B as a drug target for the treatment of diabetes II. Therefore, it has become a major target for the discovery of potent drugs for the treatment of type II diabetes and obesity. An attempt has been made in the present study to discuss the latest design and discovery of protein tyrosine phosphatase (PTP1B) inhibitors. Methods: Many PTP1B inhibitors such as diaminopyrroloquinazoline, triazines, pyrimido triazine derivatives, 2-(benzylamino)-1-phenylethanol, urea, acetamides and piperazinylpropanols, phenylsulphonamides and phenylcarboxamide, benzamido, arylcarboxylic acid derivatives, arylsupfonyl derivatives, thiazoles, isothiozolidiones and thiazolodinones have been discussed, citing the disease mechanisms. Results: The reader will gain an overview of the structure and biological activity of recently developed PTPs inhibitors. Conclusion: The co-crystallized ligands and the screened inhibitors could be used as a template for the further design of potent congeners.


2003 ◽  
Vol 23 (6) ◽  
pp. 2096-2108 ◽  
Author(s):  
Sandra Galic ◽  
Manuela Klingler-Hoffmann ◽  
Michelle T. Fodero-Tavoletti ◽  
Michelle A. Puryer ◽  
Tzu-Ching Meng ◽  
...  

ABSTRACT The human protein tyrosine phosphatase TCPTP exists as two forms: an endoplasmic reticulum-targeted 48-kDa form (TC48) and a nuclear 45-kDa form (TC45). Although targeted to the nucleus, TC45 can exit in response to specific stimuli to dephosphorylate cytoplasmic substrates. In this study, we investigated the downregulation of insulin receptor (IR) signaling by TCPTP. In response to insulin stimulation, the TC48-D182A and TC45-D182A “substrate-trapping” mutants formed stable complexes with the endogenous tyrosine-phosphorylated IR β-subunit in 293 cells. Moreover, in response to insulin stimulation, the TC45-D182A mutant accumulated in the cytoplasm of cells overexpressing the IR and in part colocalized with the IR β-subunit at the cell periphery. These results indicate that the IR may serve as a cellular substrate for both TC48 and TC45. In immortalized TCPTP−/− murine embryo fibroblasts, insulin-induced IR β-subunit tyrosine phosphorylation and protein kinase PKB/Akt activation were enhanced relative to the values in TCPTP+/+ cells. Importantly, the expression of TC45 or TC48 to physiological levels suppressed the enhanced insulin-induced signaling in TCPTP−/− cells. These results indicate that the differentially localized variants of TCPTP may dephosphorylate the IR and downregulate insulin-induced signaling in vivo.


1994 ◽  
Vol 14 (8) ◽  
pp. 5523-5532
Author(s):  
D R Stover ◽  
K A Walsh

We describe a potential regulatory mechanism for the transmembrane protein-tyrosine phosphatase CD45. Phosphorylation on both tyrosine and serine residues in vitro results in an activation of CD45 specifically toward one artificial substrate but not another. The activation of these kinases appears to be order dependent, as it is enhanced when phosphorylation of tyrosine precedes that of serine but phosphorylation in the reverse order yields no activation. Any of four protein-tyrosine kinases tested, in combination with the protein-serine/threonine kinase, casein kinase II, was capable of mediating this activation in vitro. The time course of phosphorylation of CD45 in response to T-cell activation is consistent with the possibility that this regulatory mechanism is utilized in vivo.


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