文章基本信息

标题：Identification of a human gamma-glutamyl cleaving enzyme related to, but distinct from, gamma-glutamyl transpeptidase
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作者：N Heisterkamp ; E Rajpert-De Meyts ; L Uribe 等
期刊名称：Proceedings of the National Academy of Sciences
印刷版ISSN：0027-8424
电子版ISSN：1091-6490
出版年度：1991
卷号：88
期号：14
页码：6303-6307
DOI：10.1073/pnas.88.14.6303
语种：English
出版社：The National Academy of Sciences of the United States of America
摘要：We have cloned a 2.4-kilobase cDNA from a human placental cDNA library by using a gamma-glutamyl transpeptidase [GGT; gamma-glutamyltransferase, (5-glutamyl)-peptide:amino acid 5-glutamyltransferase, EC 2.3.2.2 ] probe. The deduced amino acid sequence of this cDNA, GGT-rel, exhibited an overall similarity of 39.5% with human GGT. Sequences that could represent a heavy and a light chain, analogous to GGT, as well as a putative transmembrane region were identified in GGT-rel. Transfectants overexpressing GGT-rel were tested for their ability to catalyze cleavage of the gamma-glutamyl moiety from natural and synthetic substrates for GGT. Experiments with glutathione added to the medium suggested that GGT-rel could hydrolyze the gamma-glutamyl moiety. More definitive evidence was obtained in experiments in which this protein converted leukotriene C4 to leukotriene D4. However, GGT-rel did not convert synthetic substrates that are commonly used to assay GGT. Our results indicate that GGT can no longer be considered the only enzyme capable of cleaving the gamma-glutamyl linkage of leukotriene C4 and, most likely, of other natural compounds.