Expression of human gamma-glutamyl transpeptidase in COS CELLs.

γ-谷氨酰转肽酶(Gamma-Glamyl Transspeptidase，GT)是一种膜结合酶，它催化氨基酸和多肽中的γ-谷氨酰基部分的水解，并将其残基转移到其他氨基酸和多肽中。它被认为是一种癌胎儿蛋白，被认为参与了细胞膜的解毒、氨基酸和多肽在肝脏的转运、肾脏的氨化作用和白三烯的产生。本研究的目的是建立表达γ-GT的细胞系，以帮助了解伽马-GT在活体中的生理作用。用DEAE-葡聚糖凝胶电泳法将pSV-GT基因插入到pSV载体中，构建成pSV-GTP-GTP。Northern杂交观察到PSV-GTP在mRNA水平的瞬时表达，伽马-GTP酶分析检测细胞中合成的酶。目前，我们正在制备稳定表达的γ-GT细胞克隆。

Gamma-glutamyl transpeptidase (gamma-GT) is a membrane-bound enzyme which catalyzes hydrolysis of the gamma-glutamyl moiety of amino acids and peptides, and transfers the gamma-glutamyl residue to the other amino acids and peptides. It is considered to be an oncofetal protein and has been reported to be involved in detoxification in cell membrane transport of amino acids and peptides in liver, ammoniagenesis in kidney, and production of leucotrienes.The aim of the pres ent study was to establish the cell line which expresses gamma-GT in order to help understanding the physiological role of gamma-GT in vivo.COS cells were. transfected with PSV-GTP (which constructed by insertion of gamma-GT cDNA into PSV vector), using a DEAE Dextran method. Transient expression in PSV-GTP transfected cells was observed at a mRNA level by Northern hybridization, and the enzyme synthesized in those cells was detected by gamma-GTP enzyme assay. And at present, we are preparing the stable expression cell clones of gamma-GT.