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KMID : 0043319970200050465
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Archives of Pharmacal Research
1997 Volume.20 No. 5 p.465 ~ p.470
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Expression of Human Liver 3,4-Catechol estrogens UDP-Glucuronosyltransferase cDNA in COS 1 Cells
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Ahn Mee-Ryung
Owens Ida-S.
Sheen Yhun-Yhong
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Abstract
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The human cDNA clone UDPGTh2, encoding a liver UDP-glucuronosyltransferase (UDPGT), was isolated from a .gamma.gt 11 cDNA library by hybridization to mouse transferase cDNA clone, UDPGTm1. The two clones had 74% nlicleotide sequence identities in the coding region. UDPGTh2 encoded a 529 amino acid protein with an amino terminus membrane-insertion signal peptide and a carboxyl terminus membrane-spanning region. In order to establish substrate specificity, the clone was inserted into the pSVL vector (pUDPGTh2) and expressed in COS 1 cells. Sixty potential substrates were tested using cells transfected with pUDPGTh2. The order of relative substrate activity was as follows: 4-hydroxyestrone > estriol >2-hydroxyestriol > 4-hydroxyestradiol > -hydroxyestradiol >-androstane-, , -triol=5-androstane- , -triol. There were only trace amounts of gulcuronidation of 2-hydroxyestradiol and 2-hydroxyestrone, and in contrast to other cloned transferase, no gulcuronidation of either the primary estrogens and androgens (estrone, estradiol/testosterone, androsterone) or any of the exogenous substrates tested was detected. A lineweaver-Burk plot of the effect of 4-hydroxystrone concentration on the velocity of glucuronidation showed an apparent Km of . The unique specificity of this transferase might play an important role in regulating the level and activity of these potent and active estrogen metabolites.
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KEYWORD
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UDP-Glucuronosyltransferase cDNA, UDPGTh2, 4-Hydroxyestrone, Estriol
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