Identification and characterization of a novel human type II diacylglycerol kinase, DGKκ
Identification and characterization of a novel human type II diacylglycerol kinase, DGKκ
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DOI：
10.1074/jbc.m500669200
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发表时间：
2005-12-02
影响因子：
4.8
通讯作者：
Sakane, F
中科院分区：
文献类型：
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作者：
Imai, S;Kai, M;Sakane, F
甘油二酯激酶（DGK）通过调节磷脂酸和甘油二酯之间的平衡，在信号转导中发挥重要作用。在这里，我们确定了DGK家族的第十个成员，命名为DGK κ。κ-同工酶（1271个氨基酸，计算分子量，142 kDa）包含一个普列克底物蛋白同源结构域，两个富含半胱氨酸的锌指样结构，和一个分离的催化区，这是以前克隆的II型同工酶（DGK δ和DGK eta）常见的。新的DGK同工酶在N端增加了33个Glu-Pro-Ala-Pro串联重复序列。逆转录PCR结果显示，DGK-kappa mRNA在睾丸中的表达量最高，在胎盘中的表达量较低。DGK κ，当在HEK 293细胞中表达时，即使在没有细胞刺激的情况下也持续定位于质膜。缺失分析表明，短的C-末端序列（氨基酸残基1199-1268）是质膜定位所必需的和足够的。有趣的是，在H2 O2处理的细胞中，DGK κ，而不是其他II型DGK，通过Src家族激酶途径在Tyr（78）处特异性酪氨酸磷酸化。此外，H2 O2选择性地抑制DGK κ活性的Src家族激酶独立的方式，这表明同工酶改变了细胞膜中的信号脂质的平衡，以响应氧化应激。DGK κ的表达模式、亚细胞分布和调控机制与DGK κ和DGK κ不同，尽管结构相似性很高，这表明单个II型同工酶具有独特的功能。
Diacylglycerol kinase (DGK) plays an important role in signal transduction through modulating the balance between two signaling lipids, diacylglycerol and phosphatidic acid. Here we identified a tenth member of the DGK family designated DGK kappa. The kappa-isozyme (1271 amino acids, calculated molecular mass, 142 kDa) contains a pleckstrin homology domain, two cysteine-rich zinc finger-like structures, and a separated catalytic region as have been found commonly for the type II isozymes previously cloned (DGK delta and DGK eta). The new DGK isozyme has additionally 33 tandem repeats of Glu-Pro-Ala-Pro at the N terminus. Reverse transcriptase-PCR showed that the DGK kappa mRNA is most abundant in the testis, and to a lesser extent in the placenta. DGK kappa, when expressed in HEK293 cells, was persistently localized at the plasma membrane even in the absence of cell stimuli. Deletion analysis revealed that the short C-terminal sequence (amino acid residues 1199-1268) is necessary and sufficient for the plasma membrane localization. Interestingly, DGK kappa, but not other type II DGKs, was specifically tyrosine-phosphorylated at Tyr(78) through the Src family kinase pathway in H2O2-treated cells. Moreover, H2O2 selectively inhibited DGK kappa activity in a Src family kinase-independent manner, suggesting that the isozyme changes the balance of signaling lipids in the plasma membrane in response to oxidative stress. The expression patterns, subcellular distribution, and regulatory mechanisms of DGK kappa are distinct from those of DGK kappa and DGK kappa despite high structural similarity, suggesting unique functions of the individual type II isozymes.