Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P00492 (hypoxanthine-guanine phosphoribosyltransferase)
 2,385 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Chloramphenicol-resistant (CAPr) reconstituted cells and cybrids were isolated by fusion of karyoplasts (or intact cells) of mouse amelanotic melanoma B16 cells with cytoplasts of hypoxanthine-guanine phosphoribosyltransferase (HGPRT) -deficient, CAPr rat myoblastic cells, L6TG.CAPr, and double selection in HAT medium containing CAP. Reconstituted cells or cybrids exhibited unique cellular arrangement, and about one third of the isolated clones expressed high tyrosinase activity and marked melanin synthesis, although the parental mouse cells expressed low tyrosinase activity and the parental rat cells did not express tyrosinase activity. These phenotypic changes have been stable for more than a year. The phenotypic reversions of these clonal cells were induced by treatment with a tumor promoter. There were changes in the morphology of the treated cells to that of the mouse B16 cells and extinction of tyrosinase activity and melanin synthesis in pigmented clonal cells. These phenotypic changes and reversions induced by a promoter were repeatedly reversible.
Somatic Cell Genet 1982 Sep
PMID:Induction of supermelanin synthesis and morphological changes in interspecific reconstituted cells and its reversal by tumor promoter. 681 81

We have examined contact-mediated intercellular communication by measuring the transfer of thioguanine sensitivity to a hypoxanthine phosphoribosyltransferase (EC 2.4.2.8)-negative clone (66cl-4) selected from one subline isolated previously from a spontaneously arising mammary tumor of a BALB/cfC3H mouse. We tested other sublines from the same tumor and unrelated cell types for their ability to serve as 6-thioguanine nucleotide donors to 66cl-4 cells. The degree of communication, measured by the number of donor cells required to reduce the number of thioguanine-resistant colonies, varied with the donor cell type. The 66cl-4 line communicated with the parent cell line from which the thioguanine-resistant cell was selected and with other sublines from the parent tumor, with some unrelated tumor cells, and with some nonneoplastic cells (3T3, hamster kidney and lung fibroblasts, and mouse mammary epithelial cells). There was a quantitative difference in the amount of communication which took place with the various cells tested, but no pattern of difference could be discerned. Line 66cl-4 did not preferentially communicate with cells of epithelial versus fibroblast morphology, nor with tumor versus nontumor cells. The 66cl-4 cells retained the ability of their parent line to form metastatic tumors when injected s.c. into BALB/c mice. A quantitative selectivity of communication is thus expressed in these malignant metastatic cells, but it is apparently unrelated to either the morphological or malignant phenotype of the donor. Contact-mediated communication between tumor subpopulations may differentially affect growth and drug sensitivity within a tumor.
Cancer Res 1983 Sep
PMID:Quantitative selectivity of contact-mediated intercellular communication in a metastatic mouse mammary tumor line. 687 51

The regional gene assignments for human porphobilinogen deaminase (PBGD; EC 4.3.1.8) and esterase A4 (ESA4; EC3.1.1.1) chromosome 11 have been determined with somatic cell hybridization and immunologic, electrophoretic, and cytogenetic techniques. Dimethyl sulfoxide-induced erythroid differentiation of hybrid clones derived from the fusion of tetraploid Friend murine erythroleukemia (2S MEL) cells deficient in thymidine kinase and human Lesch--Nyhan fibroblasts (HLN) deficient in hypoxanthine phosphoribosyltransferase (HPRT-; EC 2.4.2.8) were examined for expression of human PBGD, ESA4, and lactate dehydrogenase A (LDHA; EC 1.1.1.27). Human PBGD was detected by rocket immunoelectrophoresis with rabbit anti-human PBGD IgG and by isoelectric focusing. The human chromosome complement of each clone was determined by cytogenetic and enzyme marker analyses. Of the five primary 2S MEL--HLN clones examined, three were positive for human PBGD. These were subcloned to yield a total of 10 secondary, tertiary, or quaternary clones. Analyses of these subclones permitted the regional assignment of human PBGD and ESA4 to the long arm of chromosome 11. Finer regional assignment of the loci for human PBGD and ESA4 was facilitated when two 2S MEL (HPRT-)--human fibroblast (HX/11) hybrids, each containing the X chromosome--autosome translocation (der11), t(X;11)(q25-26;q23) as the only human chromosome, were examined for expression of human PBGD, ESA4, and LDHA. One clone, HX/11-2, contained the intact X/11 translocated chromosome; in the other, HX/11-3, 11p was deleted, and the human X/11 derivative was translocated onto a mouse chromosome. HX/11-2 expressed human LDHA, but HX/11-3 did not, verifying that the latter human 11/X derivative did not include 11pter leads to 11p12; PBGD and ESA4 were not detected in either hybrid. These results confirm the location of the gene for human PBGD on chromosome 11 and establish the assignment of the loci for PBGD and ESA4 in the region 11q23 leads to 11qter.
Proc Natl Acad Sci U S A 1981 Sep
PMID:Regional gene assignment of human porphobilinogen deaminase and esterase A4 to chromosome 11q23 leads to 11qter. 694 13

The role of DNA modification in the maintenance of mammalian X-chromosome inactivation was investigated by using the technique of DNA transformation in mammalian cells. The ability of inactive X-chromosome DNA from adult mouse tissues to act in transformation for the X-linked hypoxanthine phosphoribosyltransferase gene (Hprt) could be ascertained by utilizing a recently discovered electrophoretic variant form of the hypoxanthine phosphoribosyltransferase enzyme and a previously available X:autosome translocation. Our findings indicate that inactive X-chromosome DNA from several tissues of adult female mice is strikingly inefficient, in comparison to active X-chromosome DNA, in eliciting genetic transformation for hypoxanthine phosphoribosyltransferase. These results provide in vivo evidence that is consistent with DNA modification playing an important role in the maintenance of X-chromosome inactivation.
Proc Natl Acad Sci U S A 1982 Sep
PMID:Evidence for DNA modification in the maintenance of X-chromosome inactivation of adult mouse tissues. 695 68

The levels of hypoxanthine-guanine phosphoribosyltransferase (HGPRT) were determined in lymphocytes from normal people and patients with chronic lymphocytic leukaemia (CLL). The HGPRT level in the total lymphocyte population from patients with CLL was lower than that from normal subjects. The HGPRT activity was higher in normal non-T cells than normal T cells. The enzyme activity in CLL B cells was lower than in CLL T cells. The HGPRT level was higher in CLL T cells than in normal T cells; these data suggest CLL T cells differ biochemically from their normal counterparts.
Br J Haematol 1981 Sep
PMID:Hypoxanthine-guanine phosphoribosyltransferase activity in normal and leukaemic lymphocytes. 697 4

The entire amino acid sequence of hypoxanthine-guanine phosphoribosyltransferase from human erythrocytes has been defined. Peptide fragments formed by cleavage at arginine, glutamic acid, and methionine residues were analyzed by Edman degradation or digestion with carboxypeptidase. The complete primary structure of human hypoxanthine-guanine phosphoribosyltransferase was established by sequence analysis of 17 peptide fragments, 15 of which were purified by reverse-phase high pressure liquid chromatography. The enzyme is 217 residues long with a molecular weight equal to 24,470. Mass spectroscopy indicated that the NH2-terminal alanine is acetylated.
J Biol Chem 1982 Sep 25
PMID:Human hypoxanthine-guanine phosphoribosyltransferase. Complete amino acid sequence of the erythrocyte enzyme. 710 41

We describe an assay for the quantification of reverse mutations at the hypoxanthine-guanine phosphoribosyltransferase (hgprt) locus in Chinese hamster ovary cells utilizing the selective agent L-azaserine (AS). Conditions are defined in terms of optimal AS concentration, cell density, and phenotypic expression time. After treatment, replicate cultures of 10(6) cells are allowed a 48-h phenotypic expression time in 100-mm plates. AS (10 muM) is then added directly to the growing culture and AS-resistant (ASr) cells form visible colonies. This assay is used to quantify ICR-191-, ICR-170-, and N-ethyl-N-nitrosourea-induced reversion of independently isolated HGPRT- clones. The ASr phenotype is characterized both physiologically and biochemically. All ASr clones isolated are stably resistant to AS and aminopterin but sensitive to 6-thioguanine. They also have re-expressed HGPRT enzyme. In addition, several revertants are shown to contain altered HGPRT. The data provide further evidence that ICR-191 and ICR-170 cause structural gene mutations in mammalian cells and also suggest that ICR-191, ICR-170, and N-ethyl-N-nitrosourea induce similar types of mutations in Chinese hamster ovary cells.
Mutat Res 1982 Sep
PMID:Quantification and analysis of reverse mutations at the hgprt locus in Chinese hamster ovary cells. 712 97

The phenotypic instability of a 8-azaguanine (AG)-resistant clone A14--2c-1 was previously reported (Abramyan et al., 1979) to be determined by genetic (replicative) instability. Further, phenotype gene activity changes are characteristic of genetically instable "mutant", which may be "passed" from one locus to another. In the present work, some clones were isolated from clone A14-2c-1 differing in their sensitivity to lethal UV-radiation, lethal dose D37 differences being almost 6 times. During a further cultivation through 90 passages (300 cell generations), two of four clones changed their D37 values: for clone 2c-15 it increased by 3 times, for clone 2c-16 it decreased more than twice. Besides, subclones of 2c-15 and 2c-16 clones had also different D37 values. With respect to AG-resistance, clone 2s-15 was shown to have LD50 to AG, similar to that of the parental one-while in 3 other clones LD50 was 3 times as much. These differences are associated with variations in hypoxanthine-guanine phosphoribosyltransferase (HPRT) activity: in clones A14-2c-1 and 2c-15 this activity is two times higher than in other clones. All the clones have the same value of the Michaelis constant for hypoxanthine and phosphoribosylpyrophosphate. It can be outlined that difference in HPRT activity and quantity in cells are closely related. Thus, phenotypic instability of A14-2c-1 clone offers characteristic features of genetic (replicative) instability: instability in AG-resistance and UV-sensitivity coincides with interclonal heterogeneity according to unstable markers; the unstable property may be transmitted from one locus (responsible for AG-resistance) to be another one (UV-sensitivity); and different level of AG-resistance in clones is probably determined by changes in gene activity, which lead to differences in HPRT quantity in cells.
Tsitologiia 1981 Sep
PMID:[Intraclonal heterogeneity and instability of CHO-K1 Chinese hamster cells in sensitivity to ultraviolet light and resistance to 8-azaguanine]. 729 4

The subjects of this study were individuals with the form of X-linked mental retardation that is associated with the presence of a cytologically variant X chromosome having a secondary constriction or "fragile site" at Xq 27-28 (Fra X). Studies were carried out to test the hypothesis that deletions or modifications at neighboring loci occur as a consequence of events at the fragile site. Skin fibroblasts and peripheral blood lymphocytes from affected males were analyzed with respect to the expression of two X-lined enzymes: glucose-6-phosphate dehydrogenase (G6PD) and hypoxanthine phosphoribosyltransferase (HPRT); loci for these enzymes are known to be located in the region of the fragile site. Although the number of cells resistant to thioguanine (HPRT-deficient) obtained from some cultures from one Fra X male and blood cells of another was greater than expected, the frequency of these cells was not increased in cultures from other Fra X males. Furthermore, our results indicate that the G6PD activity and electrophoretic mobility in Fra X males is similar to that in normal cells, thus providing no evidence for the loss of the long-arm telomere in the fragile X syndrome.
Am J Hum Genet 1981 Sep
PMID:Fragile X syndrome: search for phenotypic manifestations at loci for hypoxanthine phosphoribosyltransferase and glucose-6-phosphate dehydrogenase. 729 24

Protein patterns of cultured fibroblast and hair root lysates from healthy controls and patients with genetic diseases (Duchenne muscular dystrophy, Friedreich's ataxia, Marie's ataxia, Lesch-Nyhan syndrome, maple syrup urine disease, and trisomy 13, 18 and 21) were obtained with two-dimensional electrophoresis. The analysis of these patterns in 39 gels by visual comparison revealed differences in the presence and absence of 20 specific protein spots. However, this variability, which has been observed in healthy controls as well as in patients, could not provide a diagnosis for a specific genetic disease. Only in one case - trisomy 18 - was an additional spot observed, which was not present in any of the other gels.
Clin Genet 1981 Sep
PMID:High resolution protein mapping in fibroblast cell lines and hair roots from patients with genetic disease. 730 19


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