The activation of protein kinase C by the polyphosphoinositides phosphatidylinositol 4,5‐diphosphate and phosphatidylinositol 4‐monophosphate

FEBS Letters

Weinstein, I.Bernard¹  O'Brian, Catherine A.¹  Arthur, W.Lane² 

[1] Cancer Center and Institute of Cancer Research, Columbia University, 701 W. 168th St., New York, NY 10032, USA;Department of Genetics, Columbia University, 701 W. 168th St., New York, NY 10032, USA

关键词: Protein kinase C;    Polyphosphoinositide;    Tumor promoter;    Lipid cofactor;    DMSO;    dimethylsulfoxide;    PI;    phosphatidylinositol;    PI 4P;    L-α-phosphatidylinositol 4-monophosphate;    PI 4;    5DP;    L-α-phosphatidylinositol 4;    5-diphosphate;    PKC;    protein kinase C;    PMSF;    phenylmethylsulfonyl fluoride;    PS;    phosphatidylserine;    TPA;    12-O-tetradecanoylphorbol-13-acetate;   

DOI  :  10.1016/0014-5793(87)80083-2

学科分类：生物化学/生物物理

来源: John Wiley & Sons Ltd.

【 摘 要 】

Protein kinase C(PKC) is a Ca²⁺- and phospholipid-dependent protein kinase which can be activated by diacylglycerol, a product of polyphosphoinositide hydrolysis. In this report, we show that the polyphosphoinositides L-α-phosphatidylinositol 4-monophosphate (PI 4P) and L-α-phosphatidylinositol 4,5-diphosphate (PI 4,5DP) can serve as phospholipid cofactors of isolated rat brain PKC. The order of potency of the phosphoinositides in the activation of PKC, PI > PI 4P > PI 4,5DP, shows a negative correlation with the degree of acidity of the phospholipid head group, whether 1 mM Ca²⁺ or 200 nM TPA is present in the reaction assay mixture. Although the polyphosphoinositides are by themselves weaker activators of PKC than PI, small amounts of PI 4,5DP cause a two-fold enhancement of PKC in the presence of Ca²⁺ and PI. While the endogenous phospholipid cofactors of PKC remain to be identified, these results suggest that the small amounts of polyphosphoinositides which are present in cell membranes may play a direct role in the activation of PKC in vivo, by serving as phospholipid cofactors of the enzyme.

【 授权许可】

Unknown