Phosphoinositide 3-phosphatase segregates from phosphatidylinositol 3-kinase in EGF-stimulated A431 cells and fails to in vitro hydrolyse phosphatidylinositol(3,4,5) trisphosphate

• Published in: FEBS letters Vol. 341; no. 1; pp. 113 - 118
• Main Authors: Payrastre, Bernard, Gironcel, Daisy, Plantavid, Monique, Mauco, Gérard, Breton, Monique, Chap, Hugues
• Format: Journal Article
• Language: English
• Published: England Elsevier B.V 14.03.1994
• Subjects: 3T3 Cells; A431 cell; Animals; Cell Line; DMEM, Dulbecco's modified Eagle's medium; EGF, epidermal growth factor; Enzyme Activation; Epidermal Growth Factor - physiology; Humans; Hydrolysis; Mice; PBS, phosphate-buffered saline; PDGF, platelet-derived growth factor; Phosphatidylinositol 3-kinase; Phosphatidylinositol 3-Kinases; Phosphatidylinositol Phosphates - metabolism; Phosphoinositide 3-phosphatase; Phosphoric Monoester Hydrolases - metabolism; Phosphotransferases (Alcohol Group Acceptor) - metabolism; Phosphotyrosine; PKC, protein kinase C; PLC, phospholipase C; PLD, phopholipase D; PtdIns 3-kinase, phosphatidylinositol 3-kinase; PtdIns(3,4)P2, phosphatidylinositol(3,4)bisphosphate; PtdIns(3,4,5)P3, phosphatidylinositol(3,4,5)trisphosphate; PtdIns, phosphatidylinositol; PtdInsP, phosphatidylinositolphosphate; PtdS, phosphatidylserine; SAX, strong anion exchange; Substrate Specificity; PLC, phospholipase C; EGF, epidermal growth factor; PKC, protein kinase C; PtdInsP, phosphatidylinositolphosphate; Phosphotyrosine; SAX, strong anion exchange; PtdIns(3,4,5)P 3, phosphatidylinositol(3,4,5) trisphosphate; Phosphoinositide 3-phosphatase; PtdS, phosphatidylserine; PtdIns, phosphatidylinositol; PBS, phosphate-buffered saline; DMEM, Dulbecco's modified Eagle's medium; PtdIns 3-kinase, phosphatidylinositol 3-kinase; Phosphatidylinositol 3-kinase; A431 cell; PDGF, platelet-derived growth factor; PLD, phopholipase D; PtdIns(3,4)P 2, phosphatidylinositol(3,4) bisphosphate
• ISSN: 0014-5793; 1873-3468
• DOI: 10.1016/0014-5793(94)80251-3

Beside 4- and 5-phosphatases playing a role in the interconversion between the D-3 phosphorylated polyphosphoinositides, the only enzyme described so far to be responsible for a phosphomonoesterasic activity on the D-3 position of inositol lipids is a specific 3-phosphatase that hydrolyzes PtdIns(3)P in NIH 3T3 cells. We report here the presence of a potent 3-phosphatase activity in different cell types. This activity is detected both in cytosol and membranes of A431 cells and is inhibited by VO 4 3− and Zn 2+. Interestingly, the cytosolic activity from A431 cells selectively hydrolyzes in vitro PtdIns(3)P and PtdIns(3,4)P 2, whereas PtdIns(3,4,5)P 3 remains a very poor substrate under the same conditions. Finally, assays of phosphatidylinositol 3-kinase and 3-phosphatase activities in the pool of phosphotyrosine-containing proteins isolated from EGF-stimulated A431 cells suggest a compartmentation of these two antagonistic activities during cell activation.