Lai H C, Grove G, Tu C P
Nucleic Acids Res. 1986 Aug 11;14(15):6101-14. doi: 10.1093/nar/14.15.6101.
We have isolated a Yb-subunit cDNA clone from a GSH S-transferase (GST) cDNA library made from rat liver polysomal poly(A) RNAs. Sequence analysis of one of these cDNA, pGTR200, revealed an open reading frame of 218 amino acids of Mr = 25,915. The deduced sequence is in agreement with the 19 NH2-terminal residues for GST-A. The sequence of pGTR200 differs from another Yb cDNA, pGTA/C44 by four nucleotides and two amino acids in the coding region, thus revealing sequence microheterogeneity. The cDNA insert in pGTR200 also contains 36 nucleotides in the 5' noncoding region and a complete 3' noncoding region. The Yb subunit cDNA shares very limited homology with those of the Ya or Yc cDNAs, but has relatively higher sequence homology to the placental subunit Yp clone pGP5. The mRNA of pGTR200 is not expressed abundantly in rat hearts and seminal vesicles. Therefore, the GST subunit sequence of pGTR200 probably represents a basic Yb subunit. Genomic DNA hybridization patterns showed a complexity consistent with having a multigene family for Yb subunits. Comparison of the amino acid sequences of the Ya, Yb, Yc, and Yp subunits revealed significant conservation of amino acids (approximately 29%) throughout the coding sequences. These results indicate that the rat GSTs are products of at least four different genes that may constitute a supergene family.
我们从一个由大鼠肝脏多聚核糖体多聚（A）RNA构建的谷胱甘肽S-转移酶（GST）cDNA文库中分离出了一个Yb亚基cDNA克隆。对其中一个cDNA，即pGTR200进行序列分析，发现其开放阅读框为218个氨基酸，分子量为25,915。推导的序列与GST-A的19个N端残基一致。pGTR200的序列与另一个Yb cDNA，即pGTA/C44在编码区有四个核苷酸和两个氨基酸的差异，从而显示出序列微异质性。pGTR200中的cDNA插入片段在5'非编码区还包含36个核苷酸和一个完整的3'非编码区。Yb亚基cDNA与Ya或Yc cDNA的同源性非常有限，但与胎盘亚基Yp克隆pGP5有相对较高的序列同源性。pGTR200的mRNA在大鼠心脏和精囊中表达不丰富。因此，pGTR200的GST亚基序列可能代表一个基本的Yb亚基。基因组DNA杂交模式显示其复杂性与Yb亚基存在多基因家族一致。对Ya、Yb、Yc和Yp亚基的氨基酸序列进行比较，发现在整个编码序列中氨基酸有显著的保守性（约29%）。这些结果表明大鼠GST是至少四个不同基因的产物，这些基因可能构成一个超基因家族。
