scholarly journals PTPA activates protein phosphatase-2A through reducing its phosphorylation at tyrosine-307 with upregulation of protein tyrosine phosphatase 1B

2013 ◽  
Vol 1833 (5) ◽  
pp. 1235-1243 ◽  
Author(s):  
Yu Luo ◽  
Yun-Juan Nie ◽  
Hai-Rong Shi ◽  
Zhong-Fei Ni ◽  
Qun Wang ◽  
...  
Keyword(s):  
Protein Tyrosine Phosphatase ◽  
Protein Phosphatase ◽  
Protein Phosphatase 2A ◽  
Tyrosine Phosphatase ◽  
Protein Tyrosine Phosphatase 1B ◽  
Protein Tyrosine ◽  
Phosphatase 2A

scholarly journals Inactivation of p42 MAP kinase by protein phosphatase 2A and a protein tyrosine phosphatase, but not CL100, in various cell lines

1995 ◽  
Vol 5 (3) ◽  
pp. 283-295 ◽  
Author(s):  
Dario R. Alessi ◽  
Nestor Gomez ◽  
Greg Moorhead ◽  
Tom Lewis ◽  
Stephen M. Keyse ◽  
...  
Keyword(s):  
Map Kinase ◽  
Cell Lines ◽  
Protein Tyrosine Phosphatase ◽  
Protein Phosphatase ◽  
Protein Phosphatase 2A ◽  
Tyrosine Phosphatase ◽  
Protein Tyrosine ◽  
Phosphatase 2A

Glycogen synthase kinase-3β regulates Tyr307 phosphorylation of protein phosphatase-2A via protein tyrosine phosphatase 1B but not Src

2011 ◽  
Vol 437 (2) ◽  
pp. 335-344 ◽  
Author(s):  
Xiu-Qing Yao ◽  
Xiao-Xue Zhang ◽  
Yang-Yang Yin ◽  
Bin Liu ◽  
Dan-Ju Luo ◽  
...  
Keyword(s):  
Protein Tyrosine Phosphatase ◽  
Protein Phosphatase ◽  
Glycogen Synthase ◽  
Protein Phosphatase 2A ◽  
Tyrosine Phosphatase ◽  
Glycogen Synthase Kinase ◽  
Protein Tyrosine Phosphatase 1B ◽  
Glycogen Synthase Kinase 3Β ◽  
Phosphatase 2A ◽  
Gsk 3Β

GSK-3β (glycogen synthase kinase-3β), a crucial tau kinase, negatively regulates PP2A (protein phosphatase 2A), the most active tau phosphatase that is suppressed in the brain in AD (Alzheimer's disease). However, the molecular mechanism is not understood. In the present study we found that activation of GSK-3β stimulates the inhibitory phosphorylation of PP2A at Tyr307 (pY307-PP2A), whereas inhibition of GSK-3β decreased the level of pY307-PP2A both in vitro and in vivo. GSK-3β is a serine/threonine kinase that can not phosphorylate tyrosine directly, therefore we measured PTP1B (protein tyrosine phosphatase 1B) and Src (a tyrosine kinase) activities. We found that GSK-3β can modulate both PTP1B and Src protein levels, but it only inhibits PTP1B activity, with no effect on Src. Furthermore, only knockdown of PTP1B but not Src by siRNA (small interfering RNA) eliminates the effects of GSK-3β on PP2A. GSK-3β phosphorylates PTP1B at serine residues, and activation of GSK-3β reduces the mRNA level of PTP1B. Additionally, we also observed that GSK-3 negatively regulates the protein and mRNA levels of PP2A, and knockdown of CREB (cAMP-response-element-binding protein) abolishes the increase in PP2A induced by GSK-3 inhibition. The results of the present study suggest that GSK-3β inhibits PP2A by increasing the inhibitory Tyr307 phosphorylation and decreasing the expression of PP2A, and the mechanism involves inhibition of PTP1B and CREB.

scholarly journals Protein phosphatase 2A is a specific protamine-kinase-inactivating phosphatase

1992 ◽  
Vol 287 (3) ◽  
pp. 1019-1022 ◽  
Author(s):  
G D Amick ◽  
S A G Reddy ◽  
Z Damuni
Keyword(s):  
Protein Tyrosine Phosphatase ◽  
Protein Phosphatase ◽  
Kinase Activity ◽  
Protein Phosphatase 2A ◽  
Tyrosine Phosphatase ◽  
Protein Phosphatase 1 ◽  
Protein Phosphatase 2B ◽  
2B Protein ◽  
Phosphatase 2A ◽  
Protamine Kinase

Purified preparations of a protamine protein kinase from bovine kidney cytosol [Damuni, Amick & Sneed (1989) J. Biol. Chem. 264, 6412-6416] were inactivated after incubation with near-homogeneous preparations of protein phosphatase 2A1 and protein phosphatase 2A2. These protein phosphatase 2A-mediated inactivations of the protamine kinase were unaffected by highly purified preparations of inhibitor 2, but were prevented when the incubations were performed in the presence of 100 nM microcystin-LR, 100 nM okadaic acid or 0.2 mM-ATP. By contrast, highly purified preparations of protein phosphatase 2B, protein phosphatase 2C, the catalytic subunit of protein phosphatase 1, and two forms of a protein tyrosine phosphatase, designated PTPase 1B and T-cell PTPase, had little effect, if any, on protamine kinase activity. Purified preparations of the protamine kinase did not react with anti-phosphotyrosine antibodies, as determined by Western blotting and immunoprecipitation analysis. The results indicate that protein phosphatase 2A is a specific protamine-kinase-inactivating phosphatase.

Inhibition of Protein Tyrosine Phosphatase 1B by Lutein Derivatives isolated from Mexican Oregano (Lippia graveolens)

2018 ◽  
Vol 17 (3) ◽  
pp. 134-139
Author(s):  
R.M. Perez-Gutierrez
Keyword(s):  
Protein Tyrosine Phosphatase ◽  
Inhibitory Activity ◽  
Spectroscopic Data ◽  
Methanol Extract ◽  
Tyrosine Phosphatase ◽  
Positive Control ◽  
Protein Tyrosine Phosphatase 1B ◽  
Protein Tyrosine ◽  
Ic50 Value ◽  
Ic50 Values

Methanol extract from Lippia graveolens (Mexican oregano) was studied in order to identify inhibitory bioactives for protein tyrosine phosphatase 1B (PTP1B). Known flavone as lutein (1), and another flavone glycoside such as lutein-7-o-glucoside (2), 6-hydroxy-lutein-7-ohexoside (3) and lutein-7-o-ramnoide (4) were isolated from methanol extract of aerial parts of the Lippia graveolens. All isolates were identified based on extensive spectroscopic data analysis, including UV, IR, NMR, MS and compared with spectroscopic data previously reported. These flavones were evaluated for PTP1B inhibitory activity. Among them, compounds 1 and 3 displayed potential inhibitory activity against PTP1B with IC50 values of 7.01 ± 1.25 μg/ml and 18.4 μg/ml, respectively. In addition, compound 2 and 4 showed moderate inhibitory activity with an IC50 value of 23.8 ± 6.21 and 67.8 ± 5.80 μg/ml respectively. Among the four compounds, luteolin was found to be the most potent PTP1B inhibitor compared to the positive control ursolic acid, with an IC50 value of 8.12 ± 1.06 μg/ml. These results indicate that flavonoids constituents contained in Lippia graveolens can be considered as a natural source for the treatment of type 2 diabetes.

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