Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:2.3.1.28 (chloramphenicol acetyltransferase)
 5,100 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

A rat medullary thyroid carcinoma, which was previously shown to produce high levels of immunoreactive cholecystokinin (CCK), was used to establish a stable cell line. Transplantable tumors were subjected to four series of alternate in vitro and in vivo passages. Cells were prepared from the fourth series of tumors under serum-free medium conditions that prevent fibroblast growth. Subcloning of these cells yielded several propagatable clonal cell lines. One cell line with immunoreactive CCK-8 production was selected for further studies. This high CCK cell line, WE4/2, produces and secretes a CCK-immunoreactive product that coelutes with synthetic CCK-8 sulfate during Sephadex chromatography and HPLC. Northern analysis with a rat CCK cDNA revealed that the cultured cells produce a CCK RNA the same size and with the same 5' end as that previously reported for brain and intestines. In addition, a recombinant plasmid containing about 800 basepairs of 5' flanking sequence of the rat CCK gene linked to the coding sequence of the bacterial chloramphenicol acetyltransferase gene elicited a high level of chloramphenicol acetyltransferase activity when transfected into the WE4/2 cell line. Therefore, the WE4/2 cell line provides a model system for studying CCK gene expression and biosynthesis.
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PMID:Establishment of a cholecystokinin-producing rat medullary thyroid carcinoma cell line. 275 80

The gene for rat cholecystokinin (CCK) was isolated from a rat genomic DNA library. The transcription unit spans 7 kilobases and is interrupted by two introns. The initiator methionine codon lies 2 bases into exon 2; therefore, exon 1 is a noncoding exon. The transcription initiation site was determined using avian myeloblastosis reverse transcriptase, a cDNA primer, and mRNA isolated from a rat medullary thyroid carcinoma. A "TATA"-like sequence precedes the transcription initiation site at position -34. The polyadenylation site for the gene was mapped by a nuclease protection assay using a cRNA generated by transcription of the exon 3 region of the CCK gene with SP6 bacteriophage RNA polymerase. The sequence AT-TAAA is found 22 bases 5' to the site determined to be the polyadenylation addition site. Two regions of simple repetitive DNA occur within the CCK lambda clone, one within intron 2 and the other 4 kilobases 3' to the gene. Sequence analysis of the repetitive element 3' distal to the gene revealed two copies of the sequence 5'-(AC)n-3', where n is 22 and 25. A 114-base pair sequence of predominantly repeating purine-pyrimidine nucleotides separates these two d(AC) repeats. Transcriptional control elements were investigated by fusing regions of the CCK gene to the structural gene encoding chloramphenicol acetyltransferase. Promoter activity was determined by transfecting COS-7 cells with plasmids containing the gene fusions, followed by determining chloramphenicol acetyltransferase activity in cellular extracts. The region necessary for expression of the CCK gene fusions in COS-7 cells is within 144 bases 5' to the initiation of transcription.
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PMID:A gene encoding rat cholecystokinin. Isolation, nucleotide sequence, and promoter activity. 298 40