Diacylglycerol kinase θ binds to and is negatively regulated by active RhoA
Diacylglycerol kinase θ binds to and is negatively regulated by active RhoA
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DOI：
10.1074/jbc.274.11.6820
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发表时间：
1999-03-12
影响因子：
4.8
通讯作者：
van Blitterswijk, WJ
中科院分区：
文献类型：
--
作者：
Houssa, B;de Widt, J;van Blitterswijk, WJ
二酰基甘油激酶（DGK）磷酸化第二信使二酰基甘油以产生磷脂酸。迄今为止，对DGK活性的调节知之甚少。我们先前已经鉴定了DGK θ同种型，其主要在脑中表达（Houssa，B，，Schaap，D.，货车der Wal，J.，后藤，K.，近藤，H.，Yamakawa，A.，柴田先生，竹轮，T.，和货车Blitterswijk，W. J.（1997）J. Biol，Chem.272，10422-10428），我们现在报道DGK θ在转染的COS细胞以及未转染的神经元N1 E-115细胞中特异性结合活化的RhoA。结合被RhoA的效应环中的点突变（Y34 N）消除。DGK θ不与无活性RhoA结合，也不与其他Rho家族GTP酶Rac或Cdc 42结合。与活性RhoA一样，DGK θ定位于质膜。引人注目的是，活化的RhoA与DGK θ的结合完全抑制了DGK催化活性。我们的研究结果表明，DGK θ是RhoA的下游效应器，其活性受RhoA的负调控。通过积累新产生的二酰甘油，RhoA介导的DGK θ抑制可能导致增强的PKC活性响应于外部刺激。
Diacylglycerol kinase (DGK) phosphorylates the second messenger diacylglycerol to yield phosphatidic acid. To date, very little is known about the regulation of DGK activity. We have previously identified the DGK theta isotype, which is predominantly expressed in brain (Houssa, B,, Schaap, D., van der Wal, J., Goto, K., Kondo, H., Yamakawa, A., Shibata, M., Takenawa, T., and Van Blitterswijk, W. J. (1997) J. Biol, Chem. 272, 10422-10428), We now report that DGK theta binds specifically to activated RhoA in transfected COS cells as well as in nontransfected neuronal N1E-115 cells. Binding is abolished by a point mutation (Y34N) in the effector loop of RhoA DGK theta does not bind to inactive RhoA, nor to the other Rho-family GTPases, Rac or Cdc42, Like active RhoA, DGK theta localizes to the plasma membrane. Strikingly, the binding of activated RhoA to DGK theta completely inhibits DGK catalytic activity. Our results suggest that DGK theta is a downstream effector of RhoA and that its activity is negatively regulated by RhoA, Through accumulation of newly produced diacylglycerol, RhoA-mediated inhibition of DGK theta may lead to enhanced PKC activity in response to external stimuli.