Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:2.4.2.7 (adenine phosphoribosyltransferase)
 692 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Mouse fibroblast cell lines which secrete bovine (b) GH have been generated. This was accomplished by cotransforming mouse L cells (thymidine kinase-negative [TK-] and adenine phosphoribosyl transferase-negative [APRT-]) with DNA molecules encoding the Rous sarcoma virus-long-terminal repeat and bGH genes along with the herpes viral TK gene and the hamster APRT gene. One stable cell line, Pd lambda-pbGH 4-13, was found to secrete approximately 75 micrograms bGH per 24 h/5.0 X 10(6) cells. Media from this cell line were collected for purification of recombinant bGH (rbGH). Purification involved (NH4)2SO4 fractionation, ion-exchange chromatography, and gel filtration on Sephacryl S-200. The rbGH was characterized by bioassay, RIA, radioreceptor assay, and sodium dodecyl sulfate gel electrophoresis. Results of these analyses were compared with those obtained with a highly purified pituitary bGH. In the rat tibia bioassay, rbGH was found to be as potent as pituitary bGH. Results from the RIA, radioreceptor assay, and sodium dodecyl sulfate gel electrophoresis and Western blot analysis also suggested that the rbGH was similar to that of pituitary origin. Amino acid composition, partial (amino-terminal) sequence, and tryptic peptide maps were also found to be similar between the rbGH and pituitary bGH preparations. The amino terminus of the rbGH showed similar heterogeneity to that of the bGH of pituitary origin. We conclude that rbGH which was synthesized, processed, and secreted from transformed mouse fibroblasts possessed almost exactly the same physiochemical properties as pituitary bGH.
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PMID:Purification and physiochemical properties of a recombinant bovine growth hormone produced by cultured murine fibroblasts. 375

Unmethylated CpG islands are known to keep adjacent promoters transcriptionally active. In the CpG island adjacent to the adenosine phosphoribosyltransferase gene, the protection against transcriptional silencing can be attributed to the short CpG-rich core element containing Sp1 binding sites. We report here the insertion of this CpG island core element, IE, into the long terminal repeat of a retroviral vector derived from Rous sarcoma virus, which normally suffers from progressive transcriptional silencing in mammalian cells. IE insertion into a specific position between enhancer and promoter sequences led to efficient protection of the integrated vector from silencing and gradual CpG methylation in rodent and human cells. Individual cell clones with IE-modified reporter vectors display high levels of reporter expression for a sustained period and without substantial variegation in the cell culture. The presence of Sp1 binding sites is important for the protective effect of IE, but at least some part of the entire antisilencing capacity is maintained in IE with mutated Sp1 sites. We suggest that this strategy of antisilencing protection by the CpG island core element may prove generally useful in retroviral vectors.
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PMID:The core element of a CpG island protects avian sarcoma and leukosis virus-derived vectors from transcriptional silencing. 1855 Jun 62