title: A major lienal phosphotyrosine phosphatase is inhibited by phospholipids and inositol trisphosphate.
abstract: A major "non-receptor" phosphotyrosine-specific protein phosphatase isolated from the 30,000g pellet fraction of porcine spleen is related to the human T-cell tyrosine phosphatase (Cool et al. (1989) Proc. Natl. Acad. Sci. U.S.A. 86, 5257-5261) and is strongly inhibited by micromolar concentrations of phosphatidyl inositol (IC50 6 microM) and phosphatidyl serine (IC50 3.7 microM). In addition, the enzyme is inhibited by myo-inositol 1,4,5-trisphosphate (IC50 ca. 2 microM) in a non-competitive manner but not by myo-inositol hexaphosphate. Since the overall cellular tyrosine phosphatase activity greatly exceeds tyrosine kinase activity, inhibition of the phosphatase may be of importance for the regulation of the extent of tyrosine phosphorylation of cellular proteins.
authors: Faculty of Biology, University of Konstanz, Germany.
authors: C
authors: C
authors: Stader
authors: H W
authors: HW
authors: Hofer
mesh_terms: D000818:Animals; D002848:Chromatography, DEAE-Cellulose; D006801:Humans; D015544:Inositol 1,4,5-Trisphosphate / Q000494:pharmacology*; D007700:Kinetics; D010743:Phospholipids / Q000494:pharmacology*; D010833:Phytic Acid / Q000494:pharmacology; D017027:Protein Tyrosine Phosphatases / Q000037:antagonists & inhibitors* / Q000302:isolation & purification; D013154:Spleen / Q000201:enzymology*; D013347:Subcellular Fractions / Q000201:enzymology; D013552:Swine; D013601:T-Lymphocytes / Q000201:enzymology*
chemical_list: D010743:Phospholipids; D010833:Phytic Acid; D015544:Inositol 1,4,5-Trisphosphate; D017027:Protein Tyrosine Phosphatases