Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:2.4.2.8 (hypoxanthine-guanine phosphoribosyltransferase)
 2,527 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Chinese hamster X mouse somatic cell hybrids segregating mouse chromosomes were examined for their mouse chromosome content using trypsin-Giemsa (GTG) banding and Hoechst 33258 staining techniques. Simultaneously, they were scored for the presence of 24 mouse enzymes. The results confirm the assignments of 11 genes previously mapped by sexual genetics: Dip-1 and Id-1 to chromosome 1; Pgm-2 and Pgd to 4; Pgm-1 to 5; Gpi-1 to 7; Gr-1 to 8; Mpi-1 and Mod-1 to 9; Np-1 and Es-10 to 14. They also confirm chromosomally the assignments of 3 genes that were made by other somatic cell genetic studies: Aprt to 8; Hprt and alpha-gal to the X chromosome. But most importantly, four enzyme loci are assigned to four chromosomes that until now were not known to carry a biochemical marker which is expressed in cultured cells: Trip-1 to 10; Dip-2 to 18; Acp-1 to 12; and Ak-1 to 2. Cytogenetic examination of clones showing discordant segregation of HPRT and A-GAL, suggested the assignment of alpha-gal to region XE leads to XF of the mouse X chromosome. The cytologic studies provide a comparison between data from sexual genetics and somatic cell hybrids and validate hybrid cell techniques. They provide evidence of the reliability of scoring chromosomes by GTG and Hoechst staining and stress the importance of identifying clones with multiple chromosome rearrangements. Striking examples of norandom segregation of mouse chromosomes were observed in these hybrids with preferential retention of 15 and segregation of 11 and the Y chromosome.
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PMID:Gene mapping in Mus musculus by interspecific cell hybridization: assignment of the genes for tripeptidase-1 to chromosome 10, dipeptidase-2 to chromosome 18, acid phosphatase-1 to chromosome 12, and adenylate kinase-1 to chromosome 2. 19 84

We have used trypsin-Wright's banding ("GTG-banding") to analyze the chromosome content in two sublines of the SV40-transformed human cell line LNSV, derived from fibroblasts of a patient with HPRT deficiency. Both LNSV sublines (GM-847 and "LNSV") were heteroploid and showed considerable numerical and structural chromosome variability. Nineteen rearranged chromosomes which were observed at high frequency have been set aside as "marker chromosomes," and their probable derivation from normal human chromosomes has been described in PARIS CONFERENCE (1971) nomenclature. Heterogeneity within these uncloned sublines appears to increase with time in culture, and no evidence was found for evolution of a karyotypically stable cell population. The results are of general significance for cell genetic studies using established cell lines.
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PMID:Karyotype evolution of the simian virus 40--transformed human cell line LNSV. 21 30

Hypoxanthine phosphoribosyltransferase (HPRT, IMP:pyrophosphate phosphoribosyltransferase, EC 2.4.2.8) can be purified 5-to 10,000-fold from extracts of HeLa (human) cells by a three-step procedure consisting of high-speed centrifugation, adsorption to Sepharose-conjugated HPRT antibody, and sodium dodecyl sulfate/polyacrylamide gel electrophoresis. Purified enzyme labeled in vivo with radioactive lysine, arginine, or methionine was digested with trypsin and the tryptic peptides were separated by column chromatography on Bio-Rad cation exchanger Aminex A-5. Less than 50 ng (2 pmol) of HPRT is required to produce a tryptic peptide pattern. A methionine-labeled peptide was identified as the COOH-terminus because it was not labeled with either lysine or arginine. We have compared the tryptic peptide patterns of normal HeLaHPRT and a crossreacting HPRT protein lacking enzyme activity from HeLa mutant H23 [Milman et al. (1976) Proc. Natl. Acad. Sci. USA 73, 4589--4593]. The mutant protein has a new lysine-labeled peptide, but the chromatography patterns of arginine- or methionine-labeled peptides appear identical to those of the normal protein. The appearance in the H23 mutant HPRT protein of a new tryptic peptide provides strong evidence for a mutation in the HPRT structural gene. The tryptic peptide patterns were used to determine the total number of residues of labeled amino acid in the protein, and the values are reasonably consistent with those determined by conventional amino acid analysis pf erythrocyte HPRT.
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PMID:Tryptic peptide analysis of normal and mutant forms of hypoxanthine phosphoribosyltransferase from HeLa cells. 26 86

In the search for homologous chromosome regions in man and mouse, the locus for cytoplasmic superoxide dismutase (SOD-1; superoxide:superoxide oxidoreductase, EC 1.15.1.1) is of particular interest. In man, the SOD-1 gene occupies the same subregion of chromosome 21 that causes Down syndrome when present in triplicate. Although not obviously implicated in the pathogenesis, SOD-1 is considered to be a biochemical marker for this aneuploid condition. Using a set of 29 mouse-Chinese hamster somatic cell hybrids, we assign Sod-1 to mouse chromosome 16. Isoelectric focusing permits distinction between mouse and Chinese hamster isozymes, and trypsin/Giemsa banding distinguishes mouse from Chinese hamster chromosomes. The mouse fibroblasts used were derived from a male mouse carrying Searle's T(X;16)16H reciprocal translocation in which chromosomes X and 16 have exchanged parts. Analysis of informative hybrids leads to regional assignment of Sod-1 to the distal half of mouse chromosome 16 (16B4 --> ter). Because the Chinese hamster cell line (380) used for cell hybridization is deficient in hypoxanthine phosphoribosyltransferase (HPRT; IMP: pyrophosphate phosphoribosyltransferase, EC 2.4.2.8), that part of the mouse X chromosome carrying the complementing Hprt gene can be identified by selection in hypoxanthine/aminopterin/thymidine medium and counterselection in 8-azaguanine. Mouse Hprt is on the X(T) translocation product containing the proximal region X cen --> XD.
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PMID:Assignment of the gene for cytoplasmic superoxide dismutase (Sod-1) to a region of chromosome 16 and of Hprt to a region of the X chromosome in the mouse. 29 39

A somatic cell hybrid containing a single human X chromosome bearing the Xq27 fragile site was lethally irradiated and re-hybridized to its HPRT- Chinese hamster parent. One of 24 colonies surviving selection for HPRT was found to have retained human G6PD but not PGK. This line, X3000-11, which shows Xq24-qter translocated to a hamster chromosome by trypsin G-banding and a single human chromatin fragment corresponding to this segment of the X by G-11 staining, expresses the fragile site on exposure to 5-fluorodeoxyuridine. Dot blots using total human DNA suggest that X3000-11 retains approximately 0.2% of the human genome. By Southern blotting, X3000-11 retains Factor IX, DXS11 and DXS42 but lacks DXYS1, DXS3 and DXS17. This hybrid is being used to construct a cosmid library in the vector pCOS2 from which a sub-library of 500-1000 clones of human origin will be isolated using in vivo recombination with cloned Alu and Kpn family repeats. Such a sub-library will greatly facilitate chromosome walking to the fragile site as well as the testing of individual clones for their ability to create a folate-sensitive fragile site by DNA transfer into permissive Chinese hamster recipient cells.
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PMID:A rodent-human hybrid containing Xq24-qter translocated to a hamster chromosome expresses the Xq27 folate-sensitive fragile site. 293

For comparative studies we have used the somatic cell hybridization approach to regionally map genes on the mouse X chromosome. Fibroblasts from a mouse with the balanced reciprocal translocation T(XD;16B5)16H were fused with a Chinese hamster cell line (V79/380-6) deficient in activity of the enzyme hypoxanthine phosphoribosyltransferase (HPRT). Interpecific cell hybrids were initially selected for retention of the mouse translocation chromosome carrying the Hprt gene. Subsequently, hybrid clones were counterselected to force segregation of this chromosome. Selected and counterselected hybrid clones were analyzed for their chromosome content by trypsin/Giemsa banding and for expression of the mouse forms of the X-linked enzymes HPRT and alpha-galactosidase (GALA) by isoelectric focusing. The results indicate that the breakpoint on the mouse X chromosome (in band XD) has separated the genes for HPRT (Hprt) and for GALA (Ags). Hprt is proximal to the breakpoint in region Xcen-XD and Ags is distal in region XD-Xter. The gene order in the mouse (centromere-Hprt-Ags) is therefore inverted when compared to the order of the homologous loci on the long arm of the human X (centromere-GALA-HPRT).
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PMID:Comparative gene mapping: order of loci on the X chromosome is different in mice and humans. 625 72

Labeling of human and schistosomal hypoxanthine-guanine phosphoribosyltransferases (HGPRTases) with GMP-2',3'-dialdehyde (ox-GMP) results in nearly complete inactivation of the enzymes. Digestion of the [3H]ox-GMP-modified HGPRTases with trypsin followed by high-performance liquid chromatographic fractionation, partial amino acid sequencing, and mass spectral analysis of the labeled peptides revealed that four peptides from each of the two HGPRTases were labeled with ox-GMP. The conclusion from these studies indicates that two segments of the human enzyme protein, Ser 4-Arg 47 and Ser 91-Arg 100, and one region in the schistosomal enzyme, Gly 95-Lys 133, were labeled by ox-GMP. Since the ox-GMP labeling of human HGPRTase was effectively blocked by either GMP or PRibPP, whereas that of schistosomal HGPRTase was inhibited only by GMP [Kanaaneh, J., Craig, S. P., III, & Wang, C. C. (1994) Eur. J. Biochem. 223, 595-601], the two labeled peptides in human enzyme may be involved in binding to both GMP and PRibPP while the one peptide in schistosomal enzyme may be implicated only in GMP binding. We have also confirmed a previous observation [Keough, D. T., Emmerson, B. T., & de Jersey, J. (1991) Biochim. Biophys. Acta 1096, 95-100] that carboxymethylation of Cys 22 in the human HGPRTase by iodoacetate was inhibited by PRibPP. We also demonstrated that the carboxymethylation of Cys 25 in schistosomal HGPRTase by iodoacetate was specifically blocked by PRibPP. Apparently, the N-terminal regions in both enzymes are involved in PRibPP binding. The fact that ox-GMP labels the N-terminal region in human enzyme but not in schistosomal enzyme and that PRibPP protects against ox-GMP labeling in human enzyme but not in schistosomal enzyme both suggest that the amino-terminal PRibPP-binding site may be in close proximity to the GMP-binding site in human HGPRTase but not in schistosomal HGPRTase. This clear distinction between the active sites of human and schistosomal HGPRTases could be further exploited for potential opportunities for antischistosomal chemotherapy.
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PMID:Identification of the active sites of human and schistosomal hypoxanthine-guanine phosphoribosyltransferases by GMP-2',3'-dialdehyde affinity labeling. 757 12

The arginine-specific reagents phenylglyoxal and butane-2,3-dione irreversibly inactivate the Tritrichomonas foetus hypoxanthine-guanine-xanthine phosphoribosyltransferase (HGXPRT) and Schistosoma mansoni hypoxanthine-guanine phosphoribosyltransferase (HGPRT). The inactivation of the tritrichomonal enzyme by phenylglyoxal follows time-dependent and concentration-dependent pseudo-first-order kinetics. Complete protection against inactivation is afforded by the addition of 25 microM GMP, whereas 5-phosphoribosyl-1-diphosphate (PRibPP) at 50-250 microM can only slow down the inactivation, without being protective. Digestion of [7-(14)C]phenylglyoxal-modified enzyme with trypsin and separation of the peptides by reverse-phase HPLC shows that only one radioactive peak is greatly diminished by incubation with 25 microM GMP or 1 mM PRibPP. Mass-spectral analysis identifies Arg155 as the target site of two molecules of phenylglyoxal that is protected by the substrates. This amino acid residue is positioned next to Tyr156, which is a highly conserved aromatic residue among all the purine phosphoribosyltransferases (PRT) and is always found stacked on top of the purine substrate. This may explain why phenylglyoxal labeling of Arg155 inactivates the enzyme and why GMP can protect Arg155 more effectively than PRibPP. Among the purine PRT in our possession, only schistosomal HGPRT, the only other enzyme that contains an arginine residue at the corresponding location (Arg187), was susceptible to phenylglyoxal and butane-2,3-dione. The presence of Lys185-Phe186 and Ser179-Trp180 at the corresponding locations in human HGPRT and Giardia lamblia GPRT, respectively, may explain their resistance to phenylglyoxal. Thus, Arg155 in T. foetus HGXPRT and Arg187 in S. mansoni HGPRT will be attractive targets for future studies.
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PMID:Inactivation of Tritrichomonas foetus and Schistosoma mansoni purine phosphoribosyltransferases by arginine-specific reagents. 910 51