Mackenzie P I, Rodbourn L
Department of Clinical Pharmacology, Flinders University of South Australia, Bedford Park.
J Biol Chem. 1990 Jul 5;265(19):11328-32.
A lambda clone containing the entire gene and flanking sequences for a form of UDP-glucuronosyltransferase (UDPGTr-2) that glucuronidates testosterone and the foreign compounds, 4-hydroxybiphenyl and chloramphenicol, has been isolated from a rat liver genomic library. Sequence analysis of this clone revealed that the UDPGTr-2 gene is approximately 12 kilobase pairs in length and consists of six exons. All introns were found to interrupt protein coding regions of the gene. Four transcriptional start sites have been identified and are located 34, 35, 38, and 39 base pairs (bp) upstream of the translation initiation site. The 5'-flanking region of the gene contains a TATA-like sequence, CATAAA, 22 bp from the first transcription start site, potential AP-1 and v-MYB binding sites, and four sequence motifs that have been found in genes that are expressed predominantly in the liver. A 323-bp fragment encompassing these elements was fused upstream in both orientations to the coding sequence of placental alkaline phosphatase to assay promoter activity. Transient transfection of various cultured cell lines with the chimeric DNA demonstrated that this fragment, in the correct orientation, was able to function as an efficient promoter in the rat hepatoma cell lines Reuber H4-II-E and McA-RH7777. It was, however, inactive in hepatoma cell lines from two other species and in cell lines derived from other tissues. These results are consistent with the physiological expression of the rat UDPGTr-2 gene and suggest that the proximal 5'-flanking region of the gene may contain information which limits its expression to the liver.
从大鼠肝脏基因组文库中分离出一个λ克隆，其包含一种尿苷二磷酸葡萄糖醛酸基转移酶（UDPGTr - 2）的完整基因及侧翼序列，该酶可使睾酮、外源化合物4 - 羟基联苯和氯霉素发生葡萄糖醛酸化反应。对该克隆进行序列分析发现，UDPGTr - 2基因长度约为12千碱基对，由六个外显子组成。所有内含子均位于该基因的蛋白质编码区。已鉴定出四个转录起始位点，它们位于翻译起始位点上游34、35、38和39个碱基对（bp）处。该基因的5'侧翼区域包含一个类TATA序列CATAAA，距第一个转录起始位点22 bp，还有潜在的AP - 1和v - MYB结合位点，以及在主要在肝脏中表达的基因中发现的四个序列基序。一个包含这些元件的323 bp片段以两个方向融合到胎盘碱性磷酸酶的编码序列上游，以检测启动子活性。用嵌合DNA对各种培养细胞系进行瞬时转染表明，该片段在正确方向上能够在大鼠肝癌细胞系Reuber H4 - II - E和McA - RH7777中作为高效启动子发挥作用。然而，它在来自其他两个物种的肝癌细胞系以及来自其他组织的细胞系中无活性。这些结果与大鼠UDPGTr - 2基因的生理表达一致，并表明该基因的近端5'侧翼区域可能包含将其表达限制在肝脏的信息。
