Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: EC:2.4.2.8 (hypoxanthine-guanine phosphoribosyltransferase)
2,527 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

We have used direct microinjection of messenger RNA into individual mouse and human cells to assay for specific translation products. We have been able to detect the synthesis of human fibroblast interferon, thymidine, kinase, hypoxanthine phosphoribosyltransferase, adenine phosphoribosyltransferase, and propionyl-CoA carboxylase in response to injected mRNA. Using the interferon system as a model, we have quantitated interferon synthesis and followed partial purification of interferon mRNA sequences on sucrose density gradients. The methods we have utilized should be applicable to other systems in which sensitive assays exist for gene products and should provide a screening procedure for isolating specific mRNA sequences.
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PMID:Biological detection of specific mRNA molecules by microinjection. 29 82

An erythromycin-resistant mutant, ERY2301, was isolated from ethidium bromide-treated HeLa cells in the presence of erythromycin at 300 micrograms/ml. ERY2301 cells were enucleated and the anucleate cytoplasts were fused with D98/AH-2, a hypoxanthine phosphoribosyltransferase-deficient variant of HeLa cells. The resultant cybrids were isolated in a double selective medium containing erythromycin and 6-thioguanine. Cybrid formation occurred at a frequency of 10(-3) to 10(-4). In vitro protein synthesis by intact and Triton X-100 treated mitochondria isolated from ERY2301 was resistant to the macrolide antibiotics erythromycin and carbomycin, but was sensitive to chloramphenicol. These results suggest that the site of erythromycin resistance in ERY2301 may be at the level of mitochondrial protein synthesis and indicate that this trait is cytoplasmically inherited and, therefore, presumably encoded in the mitochondrial genome.
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PMID:Cytoplasmic inheritance of erythromycin resistance in human cells. 29 86

The enzyme inosinic acid dehydrogenase (EC 1.2.1 [14]) was measured and partially purified (10- to 15-fold) from normal and leukemic leukocytes. From the normal blood cells, the highest activities could be detected in lymphocytes and bone marrow cells. Dependent on the blast cell count, the leukemic IMP dehydrogenase had a higher mean specific activity than the enzymes of fractionated, immature bone marrow cells, or normal granulocytes. The partially purified enzymes from the various blood cells were apparently identical; they exhibited hyperbolic substrate saturation kinetics and were inhibited by a number of purine nucleotides. For the leukemic blast cell enzyme, the Km values for the substrates, IMP and NAD+, were 28 +/- 11; 227 +/- 98 microM, and 34 +/- 10; 240 +/- 67 microM for the partially purified enzyme from normal, immature bone marrow cells. The hypoxanthine-guanine and adenine phosphoribosyltransferase activities increased in the leukemic cells when compared with mature granulocytes, but nearly always showed similar activities when compared with fractionated bone marrow cells. Only one of the 30 investigated leukemic patients exhibited a marked decrease in hypoxanthine phosphoribosyltransferase activity of 0.5 nmol/mg/h. The phosphoribosyltransferase-specific activities of the leukemic cells are more variable than for the normal ones and no correlation of enzyme activities and blast cell count was apparent.
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PMID:Inosine 5'-phosphate dehydrogenase activity in normal and leukemic blood cells. 29 19

We produced somatic cell hybrids between HT 1080-6TG human fibrosarcoma cells and either rat white blood cells (WBC) or cells directly derived from rat spleen. Karyologic and isozyme analyses of hybrid cells indicated that they preferentially lose rat chromosomes. Hypoxanthine-aminopterine thymidine-selected hybrid clones expressing rat hypoxanthine phosphoribosyltransferase (HPRT), glucose-6-phosphate dehydrogenase (G6PD), and phosphoglycerate kinase (PGK) and containing the rat X chromosome were counterselected in a medium containing 30 micrograms/ml of 6-thioguanine. Concordant loss of the rat X chromosome and of the expression of rat HPRT and G6PD was observed in the hybrid clones.
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PMID:Segregation of rat chromosomes in somatic cell hybrids between rat cells and HT 1080 human fibrosarcoma cells. 29 42

The segregation of the chick-specific HPRT gene was studied in three Chinese hamster-chick red blood cell hybrid lines. The three lines showed individual segregation kinetics, the segregation taking place in an exponential-like fashion. Bromodeoxyuridine becomes incorporated into the nuclear DNA and increases the spontaneous segregation rate.
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PMID:The effect of bromodeoxyuridine on the segregation of the chicken-specific HPRT gene from Chinese hamster-chick red blood cell somatic hybrids. 29 50

The purine phosphoribosyltransferases have emerged as important enzymes in the metabolic economy of the developing human. Hypoxanthine-guanine phosphoribosyltransferase (HGPRT, EC 2.4.2.8) catalyses the conversion of hypoxanthine and guinine into their respective nucleotides. Inherited variation in HGPRT first became evident through clinical observations with the definition of the Lesch-Nyhan syndrome. In this disorder, HGPRT activity in erythrocytes is almost zero, although the fact that sensitive electrophoretic analysis reveals a tiny amount of activity suggests that a protein of altered structure is present. Furthermore, this variant enzyme has been activated by manipulation in the presence of small amounts of normal enzyme. Nevertheless, no cross-reacting material could be detected in lysates of red cells or fibroblasts of patients with the syndrome when tested with antiserum prepared in rabbits to normal erythrocyte HGPRT. We have tested for the presence of cross-reacting material in 18 patients, and all were negative. More HGPRT variants are coming to light. Most of the patients have renal stone disease or gout but no other feature of the Lesch-Nyhan syndrome. In one family four affected males displayed about 5% of normal activity, and the enzyme migrated electrophoretically more rapidly than normal. Cross-reacting material could not be demonstrated in erythrocyte lysates, although it was clear that a variant protein was present. A boy with renal stone disease has been found to have about 1% of normal erythrocyte activity of HGPRT. Cross-reacting material was found in his erythrocytes. The data indicate that mutations which produce diminished enzyme activity in this protein with a distinct subunit structure may or may not so alter the tertiary state of the protein that immunoreactive sites are no longer available to antibody prepared against the normal enzyme. So far whenever a variant normal HGPRT has been found there has been an identifiable clinical illness. The different forms of illness provide for correlation of molecular structure and function in man.
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PMID:Genetic heterogeneity at the locus for hypoxanthine-guanine phosphoribosyltransferase. 30 34

We describe an episode of obstructive uropathy produced by xanthine precipitation in the tubules of the kidney of a patient with histiocytic lymphoma during intensive chemotherapy, despite allopurinol therapy. Urinary oxypurine-uric acid ratio suggested a subclinical deficiency of hypoxanthine-guanine phosphoribosyltransferase. Results of an assay of this enzyme confirmed the abnormality. Both parents and three brothers of the patient had normal enzyme activity. The continued importance of adequate hydration for patients who receive allopurinol during initial periods of cancer therapy is emphasized.
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PMID:Xanthine nephropathy during chemotherapy in deficiency of hypoxanthine-guanine phosphoribosyltransferase. 34 39

In the present study we tested the feasibility of utilizing a structurally modified polyene antibiotic, amphotericin B methyl ester (AME), as a half-selection agent for isolating somatic cell hybrids. By using HAT medium supplemented with AME we have isolated interspecific mouse-hamster hybrids from mixed cultures of mouse (TK-C1 ID or HPRT-A9) and hamster (BHK/C 13) cells fused with Sendai virus, lysolecithin or polyethylene glycol. Hybrid cells proliferated and clones were isolated after 2 to 3 weeks growth in three changes of HAT-AME medium and subsequent growth in HAT medium alone. In contrast, genetically deficient parental C1 1D or A9 cells and AME-sensitive BHK/C 13 cells were killed using a similar growth protocol. The described technique is simple, efficient and permits one to use a cell line without a genetic defect in combination with a genetically deficient cell type in hybrid formation.
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PMID:Selection of mouse X hamster hybrids using HAT medium and a polyene antibiotic. 35 13

Enzyme-deficient cell lines, lacking TK or HPRT and therefore unable to grow in HAT medium, may be used as feeder layers to enhance clonal growth of wild-type cells. Low numbers of wild-type test cells may be plated in HAT medium with 5 X 10(5) HAT-sensitive feeder cells per Petri dish. The feeder cells remain attached and metabolizing for 1 to 2 weeks, but ultimately die and detach, leaving colonies of test cells. This feeder layer technique is very simple and flexible and could have wide applicability.
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PMID:Use of enzyme-deficient cell lines as feeder layers. 35 15

A simple method for the quick and accurate detection of cell fusion utilizing latex particles as cytoplasmic markers was developed and is reported here. The method is particularly useful for demonstrating human skin fibroblast heterokaryons. Ingestion of latex particles did not affect the growth of primary human and established BHK(21)/C(13) hamster fibroblasts. In addition, somatic cell hybridization between hypoxanthine phosphoribosyltransferase-deficient (HPRT-) and thymidine kinase-deficient (TK-) mutants of BHK(21)/C(13) was also unaffected by lates particle ingestion.
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PMID:Use of latex particles for analysis of heterokaryon formation and cell fusion. 35 91


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