Plasma membrane-associated phosphatase activities hydrolyzing [32P]phosphotyrosyl histones and [32P]phosphatidylinositol phosphate.
We describe a procedure of preparing [32P]phosphotyrosyl histones with minimal contamination by 32P-labeled lipids; the latter was usually found to be mixed with the phosphoproteins when the cell membrane-enriched fraction of A-431 cells was used as a source of tyrosine kinase. The phosphatase activities previously found to be associated with the plasma membranes of a human astrocytoma were resolved using purified [32P]phosphotyrosyl histones and [32P]phosphatidylinositol phosphate. In comparison with the phosphotyrosyl protein phosphatase, the phosphatidylinositol phosphate phosphatase activity is more active over a broad range of pH values, and its activity is inhibited by fluoride, zinc chloride, and lower concentrations of vanadate.
D000818:Animals; D001254:Astrocytoma / Q000201:enzymology*; D002462:Cell Membrane / Q000201:enzymology; D006657:Histones / Q000378:metabolism*; D006801:Humans; D006863:Hydrogen-Ion Concentration; D006868:Hydrolysis; D007700:Kinetics; D051379:Mice; D010749:Phosphoprotein Phosphatases / Q000032:analysis* / Q000037:antagonists & inhibitors; D010744:Phosphoric Monoester Hydrolases / Q000032:analysis* / Q000037:antagonists & inhibitors; D010761:Phosphorus Radioisotopes; D017027:Protein Tyrosine Phosphatases
D006657:Histones; D010761:Phosphorus Radioisotopes; D010749:Phosphoprotein Phosphatases; D010744:Phosphoric Monoester Hydrolases; D017027:Protein Tyrosine Phosphatases; C053153:phosphatidylinositol-3,4-bisphosphate 4-phosphatase