Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: HUMANGGP:011460 (HLUG25)
 5 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Two human liver UDP-glucuronosyltransferase cDNA clones (HLUGP1 and HLUG25) were individually inserted into the eukaryotic expression vector pKCRH2. Each recombinant plasmid was cotransfected with a SFVneo vector, thereby allowing establishment of several V79 cell lines retaining the exogenous UDP-glucuronosyltransferase cDNA after selection with G418 (Geneticin). Southern blot analysis suggested that the cDNAs were integrated into the host cell genome. Northern blot and immunoblot analyses indicated that the cDNAs were correctly transcribed and translated for the production of functional enzymes. The established recombinant V79 cell lines stably expressed the UDP-glucuronosyltransferase activities towards 1-naphthol (HLUGP1) and hyodeoxycholic acid (HLUG25) at levels 10-20-fold higher than with transient expression, and in the range found in human liver. These high levels of expression of UDP-glucuronosyltransferase activity allowed the determination of apparent kinetic constants and substrate specificities of glucuronidation in the genetically engineered cell lines. HLUG25 cDNA encoded an isoform with restricted specificity towards the 6-OH group of the bile acid hyodeoxycholic acid. The other steroids, bile acids, endobiotics, and xenobiotics tested as substrates were glucuronidated in various samples of human liver microsomes, but not by this isoenzyme. This study, allowing the expression of individual UDP-glucuronosyltransferases in heterologous cells with no endogenous transferases, offered a unique solution for the characterization of UDP-glucuronosyltransferase functional heterogeneity.
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PMID:Stable expression of two human UDP-glucuronosyltransferase cDNAs in V79 cell cultures. 184 92

A human cDNA, UDPGTh-3, encoding a dihydrotestosterone/5 alpha-androstane-3 alpha,17 beta-diol UDP- glucuronosyltransferase (transferase) has been isolated and characterized. The nucleotide sequence of UDPGTh-3 encodes a 530 amino acid protein with a typical membrane insertion-signal peptide, a membrane-anchoring domain, and three potential asparagine-linked glycosylation sites. Alignment shows that this encoded isozyme is 96% identical to an apparent estriol-metabolizing isoform, HLUG4 [Coffman, B. L., et al., (1990) Arch. Biochem. Biophys. 281, 170-175]. The udpgth-3 isozyme is 78% identical to two other steroid isoforms, HLUG25 (udpgth-1) [Jackson, M. R., et al. (1987) Biochem. J. 242, 581-588; Ritter, J. K., et. al. (1992) Biochemistry 31, 3409-3414] and udpgth-2 [Ritter, J. K., et al. (1990) J. Biol. Chem. 265, 7900-7906]. udpgth-2 and udpgth-1 metabolized parallel substrates (stereospecific estriols, 3,4-catechol estrogens, and the bile salt hyodeoxycholate), except that udpgth-2 was 100-fold more effective than udpgth-1. The mRNA encoding udpgth-3 is 2.4 kb in size and is present in liver, prostate, and testis; the mRNA encoding udpgth-2 is located in liver and kidney, whereas that for udpgth-1 is liver-specific. Each of the liver mRNA species encoding udpgth-3, udpgth-2, or udpgth-1 was induced 2.5-3-fold by phenobarbital treatment of the Erythrocebus patas monkey. In 16 human liver mRNA samples, the message encoding udpgth-3 was generally uniformly expressed and that for udpgth-1 exhibited wide variations in its level, whereas that for udpgth-2 was barely detectable in nine samples and not detectable in the others. Three samples contained no message for either isoform. Substrate turnover by udpgth-3 is ranked as follows: phenolphthalein > 5 alpha-androstane-3 alpha,17 beta-diol > 5 alpha- dihydrotestosterone = 4-hydroxybiphenyl > phenolsulfonphthalein (phenol red) > phenolphthalin. Genes encoding udpgth-3, udpgth-2, and udpgth-1 mapped to human chromosome 4 with genomic DNA from human/mouse and human/hamster somatic cell hybrids; the genes encoding udpgth-1 and udpgth-2 mapped specifically to band 4q28. udpgth-3 exhibited similar Km values both for 5 alpha-dihydrotestosterone (10 microM) and for its metabolite, 5 alpha-androstane-3 alpha,-17 beta-diol (12.5 microM).(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:Characterization of a cloned human dihydrotestosterone/androstanediol UDP-glucuronosyltransferase and its comparison to other steroid isoforms. 839 10