The Experts below are selected from a list of 129 Experts worldwide ranked by ideXlab platform
David W Borhani - One of the best experts on this subject based on the ideXlab platform.
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The two toxoplasma gondii Hypoxanthine-Guanine Phosphoribosyltransferase isozymes form heterotetramers.
Journal of Biological Chemistry, 2000Co-Authors: E. Lucile White, Larry J. Ross, Sabrina Zywno-van Ginkel, Geetha Vasanthakumar, Richard L. Davis, David W BorhaniAbstract:Abstract Two isozymes of the purine salvage enzyme Hypoxanthine-Guanine Phosphoribosyltransferase (HGPRT) of the apicomplexan protozoan Toxoplasma gondii are encoded by the single HGPRT gene as a result of differential splicing. Western blotting of total T. gondii protein shows that both isozymes I and II, which differ by 49 amino acids, are expressed. Both form enzymatically active homotetramers when overexpressed inEscherichia coli. The specific activity of HGPRT-I is five times that of HGPRT-II. When both isozymes are co-expressed in E. coli, HGPRT-I·HGPRT-II heterotetramers form. The predominant heterotetramer has enzymatic activity similar to HGPRT-II, and gel filtration chromatography demonstrates that its size is intermediate between the sizes of HGPRT-I and HGPRT-II. Mass spectrometric analysis of cross-linked homo- and heterotetramers reveals species of distinct molecular mass for HGPRT-I, HGPRT-II, and HGPRT-I·HGPRT-II and suggests that the predominant heterotetramer consists of one HGPRT-I subunit and three HGPRT-II subunits. The implications of this finding are discussed.
Geetha Vasanthakumar - One of the best experts on this subject based on the ideXlab platform.
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The two toxoplasma gondii Hypoxanthine-Guanine Phosphoribosyltransferase isozymes form heterotetramers.
Journal of Biological Chemistry, 2000Co-Authors: E. Lucile White, Larry J. Ross, Sabrina Zywno-van Ginkel, Geetha Vasanthakumar, Richard L. Davis, David W BorhaniAbstract:Abstract Two isozymes of the purine salvage enzyme Hypoxanthine-Guanine Phosphoribosyltransferase (HGPRT) of the apicomplexan protozoan Toxoplasma gondii are encoded by the single HGPRT gene as a result of differential splicing. Western blotting of total T. gondii protein shows that both isozymes I and II, which differ by 49 amino acids, are expressed. Both form enzymatically active homotetramers when overexpressed inEscherichia coli. The specific activity of HGPRT-I is five times that of HGPRT-II. When both isozymes are co-expressed in E. coli, HGPRT-I·HGPRT-II heterotetramers form. The predominant heterotetramer has enzymatic activity similar to HGPRT-II, and gel filtration chromatography demonstrates that its size is intermediate between the sizes of HGPRT-I and HGPRT-II. Mass spectrometric analysis of cross-linked homo- and heterotetramers reveals species of distinct molecular mass for HGPRT-I, HGPRT-II, and HGPRT-I·HGPRT-II and suggests that the predominant heterotetramer consists of one HGPRT-I subunit and three HGPRT-II subunits. The implications of this finding are discussed.
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Isolation and sequencing of a cDNA encoding the Hypoxanthine-Guanine Phosphoribosyltransferase from Toxoplasma gondii.
Gene, 1994Co-Authors: Geetha Vasanthakumar, Sabrina Van Ginkel, Gregory ParishAbstract:A Hypoxanthine-Guanine Phosphoribosyltransferase-encoding gene (HGPRT) from Toxoplasma gondii has been isolated and sequenced. The identity of the enzyme was determined by sequence comparison and complementation in a mutant Escherichia coli.
Yasukazu Yamada - One of the best experts on this subject based on the ideXlab platform.
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hypoxanthine guanine Phosphoribosyltransferase hprt mutations in the asian population
Nucleosides Nucleotides & Nucleic Acids, 2011Co-Authors: Yasukazu Yamada, Nobuaki Wakamatsu, A. Taniguchi, Kiyoko Kaneko, Shin FujimoriAbstract:Mutation of hypoxanthine guanine Phosphoribosyltransferase (HPRT) gives rise to Lesch-Nyhan syndrome, which is characterized by hyperuricemia, severe motor disability, and self-injurious behavior, or HPRT-related gout (Kelley-Seegmiller syndrome). The marked heterogeneity of HPRT deficiency is well known, with more than 300 mutations at the HPRT gene locus having been reported (deletions, insertions, duplications, abnormal splicing, and point mutations at different sites of the coding region from exons 1 to 9). We have identified mutations in Asian families with patients manifesting different clinical phenotypes, including rare cases of female subjects, by analyzing all nine exons of the HPRT gene (HPRT1) from genomic DNA and reverse-transcribed mRNA using the polymerase chain reaction technique coupled with direct sequencing. We developed suitable methods to detect the mutations identified from respective families with HPRT deficiency. Then, prenatal genetic diagnoses in HPRT-deficient families were carried out using both mRNA and genomic DNA from chorionic villi or amniotic fluid cells. As shown here in the heterogeneity of HPRT mutations, the spectrum of 70 mutations identified in the Asian population fits the four main conclusions that emerged previously from worldwide analysis.
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Hypoxanthine guanine Phosphoribosyltransferase (HPRT) mutations in the Asian population.
Nucleosides nucleotides & nucleic acids, 2011Co-Authors: Yasukazu Yamada, Nobuaki Wakamatsu, A. Taniguchi, Kiyoko Kaneko, Shin FujimoriAbstract:Mutation of hypoxanthine guanine Phosphoribosyltransferase (HPRT) gives rise to Lesch– Nyhan syndrome, which is characterized by hyperuricemia, severe motor disability, and self-injurious behavior, or HPRT-related gout (Kelley–Seegmiller syndrome). The marked heterogeneity of HPRT deficiency is well known, with more than 300 mutations at the HPRT gene locus having been reported (deletions, insertions, duplications, abnormal splicing, and point mutations at different sites of the coding region from exons 1 to 9). We have identified mutations in Asian families with patients manifesting different clinical phenotypes, including rare cases of female subjects, by analyzing all nine exons of the HPRT gene (HPRT1) from genomic DNA and reverse-transcribed mRNA using the polymerase chain reaction technique coupled with direct sequencing. We developed suitable methods to detect the mutations identified from respective families with HPRT deficiency. Then, prenatal genetic diagnoses in HPRT-deficient families were car...
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Deficiencies of hypoxanthine guanine Phosphoribosyltransferase (HPRT)
Nihon rinsho. Japanese journal of clinical medicine, 2008Co-Authors: Yasukazu YamadaAbstract:Inherited mutations of a purine salvage enzyme, hypoxanthine guanine Phosphoribosyltransferase (HPRT, EC 2.4.2.8; MIM308000), give rise to Lesch-Nyhan syndrome (MIM300322) or HPRT-related gout called as Kelley-Seegmiller syndrome (MIM300323). In contrast with the most severe phenotype of classical Lesch-Nyhan disease (LND), the least severe phenotype is characterized by hyperuricemia without any neurological or behavioral abnormality, and designated HPRT-related hyperuricemia (HRH). In between these two extremes are phenotypes involving hyperuricemia and varying degrees of neurobehavioral abnormality but without self-injury, designated HPRT-related neurological dysfunction (HRND). Marked genetic heterogeneity of HPRT deficiency is well known. More than 300 different mutations in the HPRT gene (HPRT1 which located in Xq26.1), deletion, insertions, duplications, abnormal splicing and point mutations at different sites of the coding region from exons 1 to 9, have been identified.
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Partial Hypoxanthine-Guanine Phosphoribosyltransferase deficiency due to a newly recognized mutation presenting with renal failure in a one-year-old boy.
European journal of pediatrics, 2007Co-Authors: Yasushi Ishida, Nobuaki Wakamatsu, Asako Ishimaru, Hisamichi Tauchi, Akiko Yamaguchi, Masayoshi Yokoyama, Kazuhiro Hiroi, Yasukazu YamadaAbstract:We describe the case of a 1-year-old boy with partial Hypoxanthine-Guanine Phosphoribosyltransferase (HPRT) deficiency. At his first visit to the hospital, he was diagnosed with hyperuricemia and irreversible renal failure. The misssense mutation Asp185Gly (554A>G) was identified in exon 8 of his HPRT gene, and this mutation was inherited from the mother.
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Mutations in the hypoxanthine guanine Phosphoribosyltransferase gene (HPRT1) in Asian HPRT deficient families.
Nucleosides nucleotides & nucleic acids, 2004Co-Authors: Yasukazu Yamada, Kenichiro Yamada, Shin-ichi Sonta, Nobuaki Wakamatsu, Nobuaki OgasawaraAbstract:Inherited mutation of hypoxanthine guanine Phosphoribosyltransferase, (HPRT) gives rise to Lesch‐Nyhan syndrome or HPRT‐related gout. We have identified 34 mutations in 28 Japanese, 7 Korean, and 1 Indian families with the patients manifesting different clinical phenotypes, including two rare cases in female subjects, by the analysis of all nine exons of HPRT from the genomic DNA and reverse transcribed mRNA using PCR technique coupled with direct sequencing.
Thomas R. Skopek - One of the best experts on this subject based on the ideXlab platform.
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In Vitro Mutational Spectrum of Aflatoxin B1 in the Human Hypoxanthine Guanine Phosphoribosyltransferase Gene
Cancer research, 1994Co-Authors: Neal F. Cariello, Lisa Cui, Thomas R. SkopekAbstract:Abstract The in vitro mutational spectrum of aflatoxin B 1 (AFB1) in exon 3 of the human hypoxanthine guanine Phosphoribosyltransferase gene in B-lymphoblasts was examined by a combination of polymerase chain reaction and denaturing gradient gel electrophoresis. The cell line used in this study contained an expression vector that produced high levels of human cytochrome P450 CYP1A1. CYP1A1 metabolizes AFB1 to form an epoxide intermediate which can react with DNA. About 1200 independent mutants were induced at the hypoxanthine guanine Phosphoribosyltransferase locus by AFB1 and were selected en masse by addition of 6-thioguanine to the bulk culture. Two independent cultures were treated with AFB1. Polymerase chain reaction was used to amplify exon 3 from the complex mutant population, and denaturing gradient gel electrophoresis was used to separate wild-type DNA sequences from mutant sequences. Mutational hotspots were visible as discrete bands on the denaturing gradient gel. Scanning densitometry was used to determine the fraction of the complex population that was represented in each non-wild-type band. The bands containing the mutations were excised from the denaturing gradient gel and sequenced. In this way, the nature and frequency of mutational hotspots in a population of >1000 mutants were determined. AFB1 produced one strong mutational hotspot in exon 3. Between 10 and 17% of the AFB1-induced mutants contained a single GC→TA base substitution at base pair 209. This hotspot occurred in a GGGGGG sequence (the mutated base is underlined). This mutation was observed reproducibly in two independently treated cultures. Several other mutations were observed in only one culture but at a lower frequency. Our results are the first report of the mutational spectrum of AFB1 in a native human gene.
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In vitro mutational specificity of cisplatin in the human hypoxanthine guanine Phosphoribosyltransferase gene.
Cancer research, 1992Co-Authors: Neal F. Cariello, James A. Swenberg, Thomas R. SkopekAbstract:The in vitro mutational spectra of cisplatin [cis-diamminedichloroplatinum(II)] in exon 3 of the human hypoxanthine guanine Phosphoribosyltransferase gene in B-lymphoblasts was examined by a combination of polymerase chain reaction and denaturing gradient gel electrophoresis. Several thousand independent mutants were induced at the hypoxanthine guanine Phosphoribosyltransferase locus by cisplatin and were selected en masse by addition of 6-thioguanine to the bulk culture. Polymerase chain reaction was used to amplify exon 3 from the complex mutant population, and denaturing gradient gel electrophoresis was used to separate wild-type DNA sequences from mutant sequences. Mutational hotspots were visible as discrete bands on the denaturing gradient gel. Scanning densitometry was used to determine the fraction of the complex population represented by the novel bands. The mutant bands were excised from the denaturing gradient gel and sequenced. In this way, the nature and frequency of mutational hotspots in a population of several thousand mutants were determined. Cisplatin produced several mutational hotspots in exon 3. About 9-10% of the cisplatin-induced mutants had mutations in a GGGGGG sequence (base pairs 207-212). GC----AT substitutions at the second and third guanines in the 5'-GGGGGG-3' run made up about 2 and 4% of the induced mutants, respectively. About 4% of the induced mutants contained a GC----TA substitution at the sixth guanine. About 1% of the cisplatin-induced mutants had an AT----TA transversion in a TAGA sequence (base pair 271; mutated base is underlined). Our results are consistent with mutations occurring at GpG and ApG sites. These nucleotide sequences have been identified as the primary sites of cisplatin adduction.
E. Lucile White - One of the best experts on this subject based on the ideXlab platform.
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The two toxoplasma gondii Hypoxanthine-Guanine Phosphoribosyltransferase isozymes form heterotetramers.
Journal of Biological Chemistry, 2000Co-Authors: E. Lucile White, Larry J. Ross, Sabrina Zywno-van Ginkel, Geetha Vasanthakumar, Richard L. Davis, David W BorhaniAbstract:Abstract Two isozymes of the purine salvage enzyme Hypoxanthine-Guanine Phosphoribosyltransferase (HGPRT) of the apicomplexan protozoan Toxoplasma gondii are encoded by the single HGPRT gene as a result of differential splicing. Western blotting of total T. gondii protein shows that both isozymes I and II, which differ by 49 amino acids, are expressed. Both form enzymatically active homotetramers when overexpressed inEscherichia coli. The specific activity of HGPRT-I is five times that of HGPRT-II. When both isozymes are co-expressed in E. coli, HGPRT-I·HGPRT-II heterotetramers form. The predominant heterotetramer has enzymatic activity similar to HGPRT-II, and gel filtration chromatography demonstrates that its size is intermediate between the sizes of HGPRT-I and HGPRT-II. Mass spectrometric analysis of cross-linked homo- and heterotetramers reveals species of distinct molecular mass for HGPRT-I, HGPRT-II, and HGPRT-I·HGPRT-II and suggests that the predominant heterotetramer consists of one HGPRT-I subunit and three HGPRT-II subunits. The implications of this finding are discussed.