Phosphoinositide 3-phosphatase segregates from phosphatidylinositol 3-kinase in EGF-stimulated A431 cells and fails to in vitro hydrolyse phosphatidylinositol(3,4,5)trisphosphate
作者:, Hugues Chap
摘要:Abstract 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 VO43− and Zn2+. Interestingly, the cytosolic activity from A431 cells selectively hydrolyzes in vitro PtdIns(3)P and PtdIns(3,4)P2, whereas PtdIns(3,4,5)P3 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.
关键词:Phosphoinositide 3-phosphatase; Phosphatidylinositol 3-kinase; A431 cell; Phosphotyrosine; EGF, epidermal growth factor; PDGF, platelet-derived growth factor; PKC, protein kinase C; PLC, phospholipase C; PLD, phopholipase D; PtdS, phosphatidylserine; PtdIns, phosphatidylinositol; PtdIns(3)P, phosphatidylinositol(3)phosphate; PtdIns(3,4)P2, phosphatidylinositol(3,4)bisphosphate; PtdIns(3,4,5)P3, phosphatidylinositol(3,4,5)trisphosphate; PtdIns 3-kinase, phosphatidylinositol 3-kinase; SAX, strong anion exchange; PBS, phosphate-buffered saline; DMEM, Dulbecco's modified Eagle's medium.
论文方向:[{"id":13,"name":"细胞生物学"},{"id":879,"name":"生物化学"}]
发表期刊:FEBS Letters Volume 341, Issue 1
发表时间:Mon Mar 14 00:00:00 CST 1994
数字识别码:10.1016/0014-5793(94)80251-3
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