Isolation and characterization of the UGT2B28 cDNA encoding a novel human steroid conjugating UDP-glucuronosyltransferase
Isolation and characterization of the UGT2B28 cDNA encoding a novel human steroid conjugating UDP-glucuronosyltransferase
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DOI：
10.1021/bi002607y
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发表时间：
2001-04-03
期刊：
影响因子：
2.9
通讯作者：
Bélanger, A
中科院分区：
文献类型：
--
作者：
Lévesque, É;Turgeon, D;Bélanger, A
UDP-葡萄糖醛酸基转移酶(UGT)属于UGT2B亚家族，催化葡萄糖醛酸转移到大量的内源性化合物，特别是类固醇，以促进它们从靶细胞中消除。克隆了一个全长1666bp的新的人类UGT2B基因，编码529个氨基酸的蛋白质，命名为UGT2B28I型。糖醛酸化实验表明UGT2B28I型催化内源和外源化合物的结合。UGT2B28的组织分布显示I型转录本在肝、乳腺和LNCaP细胞中表达。另外两个UGT2B基因被分离出来，序列分析鉴定了两个截短的UGT2B28物种。UGT2B28II型与I型不同，在辅因子结合区缺失308bp，而UGT2B28III型在推测的底物结合区缺少351bp。所有的UGT2B28亚型都由一个单独的UGT2B28基因编码，该基因的基因组结构类似于目前所描述的其他UGT2B基因。虽然没有发现较短的异构体的底物，但这三种亚型都位于内质网和核周膜上，这表明缺失的结构域不是这些UGT2B蛋白亚细胞定位所必需的。然而，所有的结构域仍然是观察葡萄糖醛酸化活性所必需的。UGT2B28在乳房和肝脏中的表达表明，这种酶在这些组织中的雄激素和雌激素代谢中发挥了作用。
UDP-glucuronosyltransferase (UGT) enzymes belonging to the UGT2B subfamily catalyze the transfer of glucuronic acid to a large number of endogenous compounds, particularly steroids, to facilitate their elimination from target cells. A novel human UGT2B cDNA of 1666 bp was isolated and encodes a 529-amino acid protein named UGT2B28 type I. Glucuronidation assays demonstrated that UGT2B28 type I catalyzes the conjugation of endogenous and exogenous compounds. The tissue distribution of UGT2B28 revealed the expression of the type I transcript in the liver, breast, and LNCaP cells. Two other UGT2B cDNAs were isolated, and sequence analysis led to the identification of two truncated UGT2B28 species. UGT2B28 type II differs from type I by a deletion of 308 bp in the cofactor binding domain, whereas UGT2B28 type III lacks 351 bp in the putative substrate binding domain. All UGT2B28 isoforms are encoded by a single UGT2B28 gene which has a genomic organization similar to that of the other UGT2B genes characterized thus far. Although no substrates could be identified for the shorter isoforms, the three subtypes were shown to be located in the endoplasmic reticulum and the perinuclear membrane, demonstrating that the missing domains are not required for the subcellular localization of these UGT2B proteins. However, all the domains remain necessary for observing glucuronidation activity. The expression of UGT2B28 type I in the breast and liver suggests a role of this enzyme in the androgen and estrogen metabolism in these tissues.