Characterization of a Soluble Adrenal Phosphatidylinositol 4-Kinase Reveals Wortmannin Sensitivity of Type III Phosphatidylinositol Kinases†

摘要: Phosphorylation of phosphatidylinositol (PtdIns) by PtdIns 4-kinases is the first step in synthesis polyphosphoinositides, lipid precursors intracellular signaling molecules. We have recently identified a cytosolic 4-kinase (cPI4K) bovine adrenal cortex that distinguished from previously known its sensitivity to 3-kinase inhibitor wortmannin (WT). The present study has further characterized this soluble enzyme and compared properties those membrane-bound, type II activity III brain. enzymatic cPI4K was inhibited not only WT (IC50 ∼ 50 nM) but also LY-294002 100 μM), another 3-kinase, neither compound affected at concentrations cPI4K. In contrast enzyme, had significantly higher Km for ATP, relatively insensitive inhibition adenosine...