Zhang Hongqiao, Forman Henry Jay
School of Natural Sciences, University of California, Merced, Merced, CA 95340, USA.
Am J Respir Cell Mol Biol. 2009 Nov;41(5):509-15. doi: 10.1165/rcmb.2009-0169TR. Epub 2009 Aug 14.
gamma-Glutamyl transpeptidase (GGT) catalyzes the transfer of the glutamyl moiety from glutathione, and glutathione S-conjugates to acceptors to form another amide or to water to produce free glutamate. Functionally, GGT plays important roles in glutathione homeostasis and mercapturic acid metabolism. The expression of GGT is increased as an adaptive response upon the exposure of oxidative stress. The underlying mechanism of this, however, is nebulous, as GGT gene structure is complex and its transcription is usually controlled by multiple promoters that generate several subtypes of GGT mRNAs. Studies reveal that signaling pathways such as Ras, ERK, p38MAPK, and PI3K are involved in the induction of GGT gene expression in response to oxidative stress. Thus, not surprisingly, induction of GGT mRNA subtypes and the involvement of multiple signaling pathways vary depending on cell type and stimuli.
γ-谷氨酰转肽酶（GGT）催化谷胱甘肽的谷氨酰部分以及谷胱甘肽S-共轭物向受体的转移，以形成另一种酰胺或与水反应生成游离谷氨酸。在功能上，GGT在谷胱甘肽稳态和巯基尿酸代谢中发挥重要作用。作为对氧化应激暴露的适应性反应，GGT的表达会增加。然而，其潜在机制尚不清楚，因为GGT基因结构复杂，其转录通常由多个启动子控制，这些启动子会产生几种GGT mRNA亚型。研究表明，Ras、ERK、p38MAPK和PI3K等信号通路参与了氧化应激反应中GGT基因表达的诱导。因此，不出所料，GGT mRNA亚型的诱导以及多种信号通路的参与因细胞类型和刺激因素而异。
