The S-thiolating activity of membrane γ-glutamyltransferase:: Formation of cysteinyl-glycine mixed disulfides with cellular proteins and in the cell microenvironment
The S-thiolating activity of membrane γ-glutamyltransferase:: Formation of cysteinyl-glycine mixed disulfides with cellular proteins and in the cell microenvironment
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DOI：
10.1089/ars.2005.7.911
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发表时间：
2005-07-01
影响因子：
6.6
通讯作者：
Pompella, A
中科院分区：
文献类型：
--
作者：
Corti, A;Paolicchi, A;Pompella, A
以往的研究证明，质膜酶γ-谷氨酰基转移酶(GGT)的活性伴随着促氧化过程，产生活性氧物种和氧化细胞蛋白硫醇。本工作旨在验证GGT介导的S硫代化反应的发生和程度，并表征参与混合二硫键形成的分子物种。实验表明，源于细胞内GGT介导的谷胱甘肽(GSH)代谢的半胱氨酰甘氨酸(CG)可以有效硫化细胞内蛋白质以及细胞外环境中存在的蛋白质。随着细胞呈现高水平的GGT表达，在细胞蛋白和培养基蛋白中都可以检测到含有CG的混合二硫化物的基础水平。通过给予底物刺激这些细胞中的GGT活性会导致CG混合二硫化物的形成增加，并伴随着含有GSH的二硫化物的减少，这可能是由于GGT依赖于从系统中去除GSH所致。报道的结果表明，CG(“蛋白质S-半胱氨酸甘氨酸化”)的结合可能代表了膜GGT的一种未知功能，可能在细胞及其周围环境中发挥调节作用(S)。
Previous studies have documented that activity of the plasma membrane enzyme gamma-glutamyltransferase (GGT) is accompanied by prooxidant processes, with production of reactive oxygen species and oxidation of cellular protein thiols. The present work was aimed to verify the occurrence and extent of S-thiolation mediated by GGT and characterize the molecular species involved in mixed disulfide formation. Experiments show that the cysteinyl-glycine (CG) originating from cellular GGT-mediated glutathione (GSH) metabolism can efficiently thiolate cellular proteins, as well as proteins present in the extracellular environment. With cells presenting high levels of GGT expression, basal levels of CG-containing protein mixed disulfides are detectable, in cellular proteins, as well as in proteins of the culture medium. Stimulation of GGT activity in these cells by administration of substrates results in an increase of CG mixed disulfide formation and a concomitant decrease of GSH-containing disulfides, likely due to GGT-dependent removal of GSH from the system. The findings reported suggest that binding of CG ("protein S-cysteylglycylation") may represent an as yet unrecognized function of membrane GGT, likely playing a regulatory role(s) in the cell and its surroundings.