Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.1.30.1 (S1 nuclease)
 3,660 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The extracellular glycoprotein cytotactin is expressed in a characteristic and complex spatiotemporal sequence during development of the chicken embryo. To identify the various control elements underlying its expression, the promoter region of the cytotactin gene has been isolated and characterized. Clones were isolated from genomic libraries by using a fragment near the 5' end of the cDNA sequence. The sequence of this cDNA fragment was found to be distributed over two exons separated by a large first intron. The site of transcription initiation was determined by S1 nuclease and primer-extension mapping. Sequencing of a 4.3-kilobase (kb) genomic DNA clone that contains 3986 base pairs (bp) upstream of the RNA start site, the first exon, and part of the first intron revealed a number of sequence motifs implicated in the regulation and expression of eukaryotic genes. These included CCAAT boxes, phorbol ester-responsive elements, enhancer elements, and a consensus TATA sequence located 24 bp upstream of the major RNA cap site. The flanking sequence also contained a number of regions of dyad symmetry and direct repeats unique to cytotactin, as well as an array of A + T-rich sequences that resemble engrailed elements. Constructs containing fragments of the upstream region of the cytotactin gene fused to a promoterless gene for chloramphenicol acetyltransferase were transiently transfected into chicken embryo fibroblasts to define functional promoter sequences. Although sequences from -721 to +121 exhibited minimal promoter activity, the entire region between -3986 to +374 was required to yield maximal expression in chicken embryo fibroblasts. Transfection of the -3986/+374 chloramphenicol acetyltransferase plasmid into the human U251MG astrocytoma cells but not HT1080 fibrosarcoma cells resulted in chloramphenicol acetyltransferase expression, consistent with the observed synthesis of cytotactin protein only by the U251MG cell line. These data indicate that the chicken cytotactin promoter can control expression in a cell type-specific fashion within cells of another species. These studies provide a basis for the dissection of cis elements and trans factors that govern the developmental expression of the cytotactin gene.
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PMID:Identification and characterization of the promoter for the cytotactin gene. 169 83

Transcripts from the engrailed gene of Drosophila melanogaster have been characterized by Northern, S1 nuclease sensitivity, and primer extension analyses. The engrailed gene encodes three poly(A)+ transcripts (3.6 kb, 2.7 kb, and 1.4 kb) that derive from a 3.9-kb portion of the genome. No other transcribed regions were found up to 16 kb downstream and 48 kb upstream of the engrailed transcription unit, the portion of the genome to which engrailed mutations have been mapped. The structures of the engrailed transcripts are unaffected by lethal engrailed mutations that break the locus at points in the transcriptionally silent regions. Transcripts expressed by 145 kb of DNA that surround the engrailed locus were also identified by Northern analysis. In contrast to the large portion of the engrailed gene that is transcriptionally inactive, most of the surrounding regions are 10-fold more densely populated with transcripts. We presume that the unusually large silent region at the periphery of the engrailed transcription unit signify the presence of special mechanisms that regulate its expression.
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PMID:The transcription unit of the Drosophila engrailed locus: an unusually small portion of a 70,000 bp gene. 244 63

The invected and engrailed genes are juxtaposed in the Drosophila genome and are closely related in sequence and pattern of expression. The structure of the most abundant invected transcript was defined by obtaining the full-length cDNA sequence and by S1 nuclease sensitivity and primer extension studies; a partial sequence of the invected gene was determined; and the developmental profile of invected expression was characterized by Northern analysis and by in situ localization. The invected gene, like the engrailed gene, is expressed in the embryonic and larval cells of the posterior developmental compartments and in the embryonic hindgut, clypeolabrum, and nervous system. Like the engrailed gene, the invected gene can encode a protein of approximately 60 kD that contains a homeo box near its carboxyl terminus; indeed, a sequence of 117 amino acids in the carboxy-terminal region of both proteins is almost identical. The developmental role of the invected gene is not known.
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PMID:The invected gene of Drosophila: sequence analysis and expression studies reveal a close kinship to the engrailed gene. 289 56