Abstract
Production of PtdIns(4)P and PtdIns(4,5)P2 by plasma-membrane preparations from A431 cells was selectively stimulated in a dose-dependent manner by epidermal growth factor (EGF) in the presence of Na3VO4. Na3VO4 itself mimicked this effect, which was overcome after treatment by a specific phosphotyrosyl phosphatase isolated from A431 cells. PtdIns and PtdIns(4)P kinase activities were present in phosphotyrosyl-proteins isolated from EGF- and/or Na3VO4-stimulated A431 cells by immunoaffinity using an anti-phosphotyrosine antibody. These data suggest for the first time an EGF-dependent regulation of PtdIns 4-kinase and PtdIns(4)P 5-kinase activities by a mechanism involving a tyrosine-phosphorylation process.
Publication types
-
Research Support, Non-U.S. Gov't
MeSH terms
-
1-Phosphatidylinositol 4-Kinase
-
Adenosine Triphosphate / metabolism
-
Carcinoma, Squamous Cell
-
Cell Line
-
Chromatography, High Pressure Liquid
-
Humans
-
Kinetics
-
Membrane Proteins / isolation & purification
-
Membrane Proteins / metabolism*
-
Molecular Weight
-
Neoplasm Proteins / metabolism
-
Phosphatidylinositols / isolation & purification
-
Phosphatidylinositols / metabolism
-
Phosphoprotein Phosphatases / metabolism*
-
Phosphoproteins / isolation & purification
-
Phosphorus Radioisotopes
-
Phosphorylation
-
Phosphotransferases / metabolism*
-
Protein Tyrosine Phosphatases
-
Protein-Tyrosine Kinases / metabolism*
Substances
-
Membrane Proteins
-
Neoplasm Proteins
-
Phosphatidylinositols
-
Phosphoproteins
-
Phosphorus Radioisotopes
-
Adenosine Triphosphate
-
Phosphotransferases
-
1-Phosphatidylinositol 4-Kinase
-
Protein-Tyrosine Kinases
-
Phosphoprotein Phosphatases
-
Protein Tyrosine Phosphatases