EXTRACELLULAR GLUTATHIONE IS A SOURCE OF CYSTEINE FOR CELLS THAT EXPRESS GAMMA-GLUTAMYL-TRANSPEPTIDASE
EXTRACELLULAR GLUTATHIONE IS A SOURCE OF CYSTEINE FOR CELLS THAT EXPRESS GAMMA-GLUTAMYL-TRANSPEPTIDASE
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DOI：
10.1021/bi00075a026
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发表时间：
1993-06-22
期刊：
影响因子：
2.9
通讯作者：
RICKETTS, WA
中科院分区：
文献类型：
--
作者：
HANIGAN, MH;RICKETTS, WA
我们表明，γ-谷氨酰转肽酶（GGT）是一种谷胱甘肽酶，使细胞能够使用细胞外谷胱甘肽作为半胱氨酸的来源。我们用含有人GGT cDNA的质粒转染NIH/3 T3小鼠成纤维细胞，并获得稳定转化的细胞系，其在细胞外表面上以其适当的方向表达GGT。NIH/3 T3成纤维细胞需要半胱氨酸来生长，并且不能使用细胞外谷胱甘肽作为半胱氨酸的来源。我们证明GGT阳性成纤维细胞能够在补充谷胱甘肽的无半胱氨酸培养基中生长。来自细胞外谷胱甘肽裂解的半胱氨酸可用于维持细胞内谷胱甘肽水平。GGT阳性NIH/3 T3细胞在含有谷胱甘肽的无半胱氨酸培养基中孵育时能够补充细胞内谷胱甘肽。GGT阴性细胞不能。因此，GGT是一种谷胱甘肽酶，它为细胞提供了获得半胱氨酸的第二来源。
We show that gamma-glutamyl transpeptidase (GGT) is a glutathionase that enables cells to use extracellular glutathione as a source of cysteine. We transfected NIH/3T3 mouse fibroblasts with a plasmid containing cDNA for human GGT, and obtained stably transformed cell lines that expressed GGT in its proper orientation on the outer surface of the cell. NIH/3T3 fibroblasts require cysteine for growth and are unable to use extracellular glutathione as a source of cysteine. We demonstrate GGT-positive fibroblasts are able to grow in cysteine-free medium supplemented with glutathione. Cysteine derived from the cleavage of extracellular glutathione can be used to maintain intracellular levels of glutathione. GGT-positive NIH/3T3 cells were able to replenish intracellular glutathione when incubated in cysteine-free medium containing glutathione. GGT-negative cells could not. Therefore, GGT is a glutathionase that provides the cell with access to a secondary source of cysteine.