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)

Earlier results have demonstrated a mutagenic activity of simian virus 40 (SV40) in mammalian cells. To analyse this ability further, the effect of SV40 DNA fragments, introduced into Chinese hamster cells, on the frequency of mutations at the hypoxanthine phosphoribosyltransferase locus and other loci was studied. It was found that the mutagenic effect was substantially maintained when the viral genome had been replaced by a fragment comprising the T antigen-coding region and the early promoter-enhancer region; was strongly reduced or abolished when the promoter region including upstream sequences in this fragment had been replaced by the chicken lysozyme gene promoter or both enhancer elements were deleted, and was abolished in an SV40 replication origin-defective mutant in which the structure of the T antigen-binding site II was affected. It may be concluded that SV40-induced mutagenesis depends on the expression of the early region of the genome and on a function involved in specific binding of large T antigen to viral DNA. Since origin-defective mutants of SV40 were reported as being able to transform cells, the functions of transformation and mutation do not seem to correlate.
 ...
PMID:Simian virus 40-induced mutagenesis: action of the early viral region. 302 45

By fusion of C3H/HeJ splenic adherent mononuclear cells enriched for macrophages with HPRT-deficient C57L/J HH- hepatoma cells, we have generated six macrophage-hepatoma hybrid clones. The hybrid nature of isolated clones was demonstrated by karyotypic analysis. The hybrid clones were screened for macrophage properties by assaying the presence of two enzymes: nonspecific esterase and lysozyme. Three of six hybrids expressed higher amount of Ia antigen and less amount of FcR; the other three hybrids expressed higher amounts of Fcr, but no Ia antigen. Phagocytosis of serum-opsonized beads is positively correlated with FcR expression, while the proliferation of antigen-primed lymphocytes is only induced by antigen-pulsed hybrids expressing Ia antigen. One hybrid clone (MH3-1) secreted significantly higher level of PGE2 and also expressed Ia antigen with higher ability of antigen-presentation. The data suggest that the cell hybridization can segregate macrophage-featured phenotypes into different hybrid clones which perform distinct functions. It may facilitate the study on the relationship of macrophage functions and the relationship between the functions and defined cell structure.
 ...
PMID:Generation of phenotypically distinct macrophage-hepatoma hybrid clones. 347 90