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

We have cloned and characterized the genomic structure of the human gene for Myc-associated zinc finger protein (MAZ), which is located on chromosome 16p11.2. This gene is transcribed as an mRNA of 2.7 kilobases (kb) that encodes a 60-kDa MAZ protein. A 40-kb cosmid clone was isolated that includes the promoter, five exons, four introns, and one 3'-untranslated region. All exon-intron junction sequences conform to the GT/AG rule. The promoter region has features typical of a housekeeping gene: a high G + C content (88. 4%); a high frequency of CpG dinucleotides, in particular within the region 0.5 kb upstream of the site of initiation of translation; and the absence of canonical TATA and CAAT boxes. An S1 nuclease protection assay demonstrated the presence of multiple sites for initiation of transcription around a site 174 nucleotides (nt) upstream of the ATG codon and such expression was reflected by the promoter activity of a MAZ promoter/CAT (chloramphenicol acetyltransferase) reporter gene. Cis-acting positive and negative elements controlling basal transcription of the human MAZ gene were found from nucleotides (nt) -383 to -248 and nt -2500 to -948. Moreover, positive and negative autoregulatory elements were also identified in the regions from nt -248 to -189 and from nt -383 to -248 after co-transfection of HeLa cells with plasmids that carried the MAZ promoter/CAT construct and the MAZ-expression vector. Our results indicate that the 5'-end flanking sequences are responsible for the promoter activities of the MAZ gene.
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PMID:Genomic organization and expression of a human gene for Myc-associated zinc finger protein (MAZ). 968 18

The T-cell protein tyrosine phosphatase (TC PTP) is expressed ubiquitously at all stages of mammalian development. However, mRNA levels fluctuate in a cell-cycle-dependent manner, reaching peak levels in late G1, and rapidly decreasing in S phase. Furthermore, TC PTP being present in higher amounts in lymphoid tissues, we have recently shown that it is essential for proper maintenance of both the bone marrow micro-environment and B- and T-cell functions. In order to better understand the elements controlling the expression pattern of this gene, we have isolated and characterized approx. 4kb of the murine TC PTP promoter. DNA sequencing of the proximal 5' region revealed the absence of both TATAA and CAAT boxes. Primer extension analysis and S1 nuclease mapping techniques identified multiple transcription initiation sites. Functional promoter activity was determined using transfection experiments of promoter deletion constructs fused to a CAT reporter construct. Our results indicate that the minimal promoter sequence required for functional expression is contained within the first 147bp of the TC PTP promoter. In addition, consistent with the cell-cycle-dependent expression of TC PTP, we localized a domain between 492 and 1976bp from the transcription initiation site through which repression occurs. In conclusion, although initiator-driven transcription allows for ubiquitous expression of TC PTP, we define general transcription motifs present within the promoter that may mediate specific modulations of the TC PTP gene.
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PMID:Promoter analysis of the murine T-cell protein tyrosine phosphatase gene. 1052 59

Investigation of the expression of the riboflavin (rib) genes, which are found immediately downstream of luxG in the lux operon in Photobacterium phosphoreum, provides more information relevant to the evolution of bioluminescence, as well as to the regulation of supply of flavin substrate for bacterial bioluminescence reactions. In order to answer the question of whether or not the transcriptions of lux and rib genes are integrated, a transcriptional termination assay was performed with P. phosphoreum DNA, containing the possible stem-loop structures, located in the intergenic region of luxF and luxE (OmegaA), of luxG and ribE (OmegaB), and downstream of ribA (OmegaC). The expression of the CAT (Chloramphenicol Acetyl Transferase) reporter gene was remarkably decreased upon the insertion of the stem-loop structure (OmegaC) into the strong lux promoter and the reporter gene. However, the insertion of the structure (OmegaB) into the intergenic region of the lux and the rib genes caused no significant change in expression from the CAT gene. In addition, the single stranded DNA in the same region was protected by the P. phosphoreum mRNA from the S1 nuclease protection assay. These results suggest that lux genes and rib genes are part of the same operon in P. phosphoreum.
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PMID:Coregulation of lux genes and riboflavin genes in bioluminescent bacteria of Photobacterium phosphoreum. 1545 47

To investigate gene organization and expression signals in extreme thermophilic archaebacteria, tRNA genes were cloned from Thermoproteus tenax. Clones for five tRNA species were obtained, namely for tRNAAla (TGC), tRNAAla (CGC), tRNALeu (CAG), tRNALeu (CAA) and tRNAMet (CAT). Three of the respective genes were located singly in the chromosome, the two others (tRNAAla and tRNAMet) were clustered but in a head to head position. Four of the genes contained intervening sequences, either in the classical position 3' to the anticodon (tRNAMet), or within the anticodon sequence (tRNALeuCAG), or in the hitherto unique position 5' to the anticodon within the anticodon stem region (tRNAAla). Existence of a transcript containing the intervening sequence was demonstrated by nuclease S1 mapping. All tRNA genes were extremely rich in G-C basepairs of helical regions, a feature which may contribute to thermostability of the secondary structure. The start site of transcription of the 16S/23S rRNA operon and of two tRNA genes of Thermoproteus was determined by nuclease S1 mapping. Transcription of the tRNA genes initiates close to or immediately at the 5' end of the structural gene, that of the rRNA operon 175 bp upstream of the coding region. About 18 bp upstream of the transcription initiation site a conserved AT-rich sequence motif occurs within a fairly GC-rich intercistronic spacer. Its putative instability at the high growth temperature of Thermoproteus suggests a function as entry site for RNA polymerase.
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PMID:Genes for stable RNA in the extreme thermophile Thermoproteus tenax: introns and transcription signals. 1598 38

Hemagglutinin-neurarninidase (HN) protein was expressed in COS-7 cells, indicating that the expression of HN protein driven by SRa promoter is higher than that driven by chicken beta-actin promoter. Moreover, with 5' noncoding region (NCR) of HN gene, the expression was enhanced. Northern blotting demonstrated that this phenomenon was caused by the difference of HN mRNA transcription. To know the regulatory function of 5' NCR, HN gene 5' NCR was replaced by 5' NCR of keratin gene or cytochrome P-450 gene and the 3' NCR was deleted by site-directed mutagenesis. By using CAT gene as a reporter, S1 nuclease assay was done to quantitate the HN mRNA transcript in the COS-7 cells co-transfected with the reporter and mutated plasmids, indicating that 5' NCR is non-specific to the enhancement of HN protein expression, and the 3' NCR also has a special regulatory function.
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PMID:Regulation of noncoding region for expression of Sendai virus hemagglutinin-neuraminidase (HN) gene. 1876 26

The myc gene family, including c- and N-myc, is believed to play a critical role in the regulation of cell cycle and proliferation. The function of N-myc, in contrast to c-myc, is not clearly understood. Here we report that, using a N-myc expression vector in CAT and S1 nuclease protection assays, the N-myc protein trans-represses expression of the human N-myc, the mouse N-myc, and the human MHC class 1 antigen genes. The analysis of N-myc deletion mutants showed that the N-terminal region where there are amino acid sequences highly conserved in the myc family and the central region where the acidic amino acids are concentrated, are necessary for trans-repression activity. Also, the region near the C-terminus is relevant for DNA-protein and protein-protein interaction; in particular, the basic region, helix-loop-helix, and leucine zipper are important for activity.
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PMID:Determination of transrepression domains of the human N-myc protein. 2158 77


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