Sakamuro D, Yamazoe M, Matsuda Y, Kangawa K, Taniguchi N, Matsuo H, Yoshikawa H, Ogasawara N
Department of Biochemistry, Osaka University Medical School, Japan.
Gene. 1988 Dec 15;73(1):1-9. doi: 10.1016/0378-1119(88)90307-1.
A cDNA hybridizable to that of rat gamma-glutamyl transpeptidase (GGT) was cloned from a cDNA library of human fetal liver. The insert of the cDNA clone contained 1866 bp consisting of an open reading frame (ORF) of 1709 bp (569 amino acids (aa), N-terminal portion truncated) and a 135-bp 3'-untranslated region followed by a polyadenylated tail. In parallel, amino acid sequences of N-terminal portions of heavy and light chains of a purified human GGT were determined. Two stretches of amino acid sequences identical to the N-terminal sequences of heavy and light chains were found in the ORF. We therefore concluded that the clone is a cDNA for human GGT. From the amino acid sequence deduced from cDNA, the heavy and the light chains of the purified enzyme are estimated to be composed of 351 aa (Mr 38,336) and of 189 aa (Mr 20,000), respectively. The heavy chain is preceded by a signal peptide of at least 29 aa presumed to be cleaved by bromelain treatment. Six putative N-glycosylation sites are present in the heavy subunit region and one in the light subunit region. Primary structure and hydrophobicity profile are closely similar to those of rat GGT.
从人胎肝cDNA文库中克隆出一种可与大鼠γ-谷氨酰转肽酶（GGT）的cDNA杂交的cDNA。该cDNA克隆的插入片段包含1866 bp，由一个1709 bp的开放阅读框（ORF）（569个氨基酸（aa），N端部分截短）和一个135 bp的3'非翻译区组成，后面跟着一个聚腺苷酸化尾巴。同时，测定了纯化的人GGT重链和轻链N端部分的氨基酸序列。在该ORF中发现了两段与重链和轻链N端序列相同的氨基酸序列。因此，我们得出结论，该克隆是人类GGT的cDNA。根据从cDNA推导的氨基酸序列，纯化酶的重链和轻链估计分别由351个aa（Mr 38,336）和189个aa（Mr 20,000）组成。重链之前有一个至少29个aa的信号肽，推测经菠萝蛋白酶处理后会被切割。重亚基区域有6个推定的N-糖基化位点，轻亚基区域有1个。一级结构和疏水性图谱与大鼠GGT的非常相似。
