Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

---

Query: EC:3.1.30.2 (endonuclease)
18,621 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The Y1 mouse adrenocortical tumor cell line retains the ability to synthesize and secrete steroids, but does not express steroid 21-hydroxylase (C21) and, therefore, does not produce 21-hydroxylated steroids. In this investigation the mechanisms underlying the loss of C21 activity in the Y1 cell line were explored. A 9-kilobase BglII fragment containing the C21 gene was cloned from the Y1 genome. This genomic clone directed the synthesis of C21 transcripts and 21-hydroxylated steroid products when transfected back into the Y1 cell line. As determined by restriction endonuclease digestions with MspI and HpaII, enzymes that distinguish between unmethylated and methylated CCGG sites, the endogenous C21 gene was extensively methylated in Y1 adrenal cells and in cells from other mouse tissues that do not normally express this gene. In contrast, the C21 gene was hypomethylated in primary cultures of mouse adrenal cells which normally synthesize large amounts of C21. The cloned C21 gene transfected into Y1 cells initially was unmethylated, but became extensively methylated with prolonged culture of the cells; prolonged culture of these transfectants also resulted in a loss of C21 expression. Loss of C21 expression in Y1 transfectants, however, temporally preceded the extensive methylation of the transfected C21 gene. Furthermore, treatment of Y1 cells with 5-azacytidine caused a demethylation of the endogenous C21 gene, but did not result in the recovery of C21 expression. These results indicate that Y1 cells contain a functional C21 gene that has been silenced by a reversible cis-modification event.(ABSTRACT TRUNCATED AT 250 WORDS)
...
PMID:cis modification of the steroid 21-hydroxylase gene prevents its expression in the Y1 mouse adrenocortical tumor cell line. 170 55

Genomic DNA obtained from B lymphoblastoid cell line was digested with appropriate restriction endonuclease and hybridized with several probes specific for HLA-DQ gene. DNA probe which detects intron between DQ beta 1 and beta 2 domains suggested the intron insertion event of Alu-like repetitive sequence in DR7DQw2 haplotype. Southern hybridization with DQA1 3' untranslated (UT) region probe showed DQw2-type hybridization pattern in DR7LDQw3 haplotype. On the contrary, DQB1 3'UT region probe showed DQw3-type pattern in the same haplotype, which strongly supports the previous suggestion that recombination occurs between DQA1 and DQB1 genes in DR7DQw3 haplotype. 3'UT region probes of DQA1 and DQB1 genes failed to detect restriction fragment lenght polymorphism (RFLP) between DR4DQw3 and DR4DQw4 haplotypes. DNA sequencing of DQB1 genomic clone derived from KT3 cell line (DR4DQw4) revealed striking homology of beta 2 domain, 5'UT region, 3'UT region and intervening sequence between beta 1 and beta 2 domains in DR4DQw3 and DR4DQw4 haplotypes. This structural similarity suggests that DQw3 and DQw4 genes are generated from a common ancestral gene.
...
PMID:[Diversity of the HLA-DQ gene]. 197 41

To understand the basis of osteonectin (SPARC) transcriptional regulation, we have isolated a bovine genomic clone (lambda Og15) encoding exon 1 and 15 kilobase pairs (kb) of flanking DNA. Direct RNA sequencing of the 5' end of the osteonectin message showed it contained a sequence identical to that of a 2.4-kb EcoRI-BamHI fragment located midway in the clone lambda Og15. The results indicate exon 1 is located 10 kb away from exon 2 in the bovine genome. The DNA sequence unit CCTG is repeated five times in exon 1 which is composed exclusively of untranslated sequence. Sequence analysis of the 5'-flanking DNA revealed the presence of many regulatory motifs including a "GC" box with four overlapping SP1 consensus sequences. Immediately downstream from the GC box is a 72-base pair purine-rich stretch composed primarily of direct repeats of the sequence motifs GGGGA and GGA (GAGA box). Digestion of the flanking DNA in vitro with S1 endonuclease showed a site for the enzyme at position -55 which is just 3' to the GAGA box. Chimeric chloramphenicol acetyltransferase constructs were prepared containing the S1-sensitive site and showed substantial transcriptional activity in UMR-106 and fetal and adult human bone cells which are known to be high producers of the protein. The results indicate a potential regulatory activity of the S1 site in osteonectin gene activation.
...
PMID:Osteonectin promoter. DNA sequence analysis and S1 endonuclease site potentially associated with transcriptional control in bone cells. 253 44

Previous studies from this laboratory have demonstrated that cytosolic Ca2+ rapidly rises to supraphysiologic levels in liver cells exposed to the hepatotoxins carbon tetrachloride (CCl4) and 1,1-dichloroethylene (DCE) in vivo and in vitro. The present study examines whether this increase in intracellular Ca2+ activates endonucleases that could initiate or contribute to the ensuing hepatotoxic events. Initial experiments demonstrated that there was no generalized breakdown of hepatic DNA in intact rats exposed to CCl4 and DCE, as assessed by the appearance of nucleosomal fragments in liver nuclear DNA separated on agarose gels. Nor was generalized fragmentation observed in DNA isolated from primary hepatocyte cultures exposed to halocarbons, except at very late times following loss of plasma membrane integrity. Endonuclease activation was further examined at a more sensitive level by specifically monitoring hypersensitive sites (HSS) in serum albumin gene. Actively transcribed genes, such as albumin in liver tissue, are extremely sensitive to attack by exogenous nucleolytic enzymes at discrete sites. We speculated that subtle halocarbon-induced endonuclease activation would first become evident at these sites. To locate HSS, DNA was digested with restriction enzymes Eco R1 or Hind III, electrophoresed on agarose gels, blotted onto nitrocellulose, and hybridized to a 32P-labeled 1400 bp rat albumin genomic clone. No cleavage at hypersensitive sites was detected in DNA isolated from rat liver or hepatocyte DNA at early times when elevations of Ca2+ were developing. Thus, these data indicate that endonuclease activation by intracellular Ca2+ and resultant nucleolytic destruction of DNA is not an early event in the hepatotoxicity produced by halocarbons.
...
PMID:Halocarbon hepatotoxicity is not initiated by Ca2+-stimulated endonuclease activation. 253 8

A full-length genomic clone for human tyrosine hydroxylase (L-tyrosine, tetrahydropteridine:oxygen oxidoreductase, EC 1.14.16.2) has been isolated. A human brain genomic library constructed in EMBL3 was screened by using a rat cDNA for tyrosine hydroxylase as a probe [Brown, E. R., Coker, G. T., III, & O'Malley, K. L. (1987) Biochemistry 26, 5208-5212]. Out of one million recombinant phage, one clone was identified that hybridized to both 5' and 3' rat cDNA probes. Restriction endonuclease mapping. Southern blotting, and sequence analysis revealed that, like its rodent counterpart, the human gene is single copy, contains 13 primary exons, and spans approximately 8 kilobases (kb). In contrast to the rat gene, human tyrosine hydroxylase undergoes alternative RNA processing within intron 1, generating at least three distinct mRNAs. A comparison of the human tyrosine hydroxylase and phenylalanine hydroxylase [DiLella, A. G., Kwok, S. C. M., Ledley, F. D., Marvit, J., & Woo, S. L. C. (1986) Biochemistry 25, 743-749] genes indicates that although both probably evolved from a common ancestral gene, major changes in the size of introns have occurred since their divergence.
...
PMID:Isolation and characterization of the human tyrosine hydroxylase gene: identification of 5' alternative splice sites responsible for multiple mRNAs. 289 28

A method using restriction enzymes to locate the cap site in a cloned and sequenced 5' region of a gene is described. With a cDNA fragment (or synthetic oligonucleotide sequence), complementary to any portion of an mRNA, the position of the cap site nucleotide in a genomic clone can be precisely located. The steps include: (1) hybridization of a cDNA fragment to an mRNA sample, and reverse transcription from this primer to produce labeled, fully extended cDNA molecules, (2) hybridization of the extended cDNA to a genomic clone containing the region in which initiation occurs (previously sequenced), (3) restriction endonuclease digestion of the hybrid with two or more enzymes within the putative first exon, and (4) size analysis of the short labeled cDNA fragments produced. Multicut restriction enzymes are most useful in this technique. The sizes of the hybridized fragments correspond to the unique distances from the 5' end of the message to each of the different cleavage sites allowing the cap site to be positioned in the genomic sequence.
...
PMID:Mapping a mammalian mRNA cap site by restriction digestion of hybridized cDNA. 300 19

A DNA probe specific for the HLA-B locus has been isolated from a broadly cross-reactive HLA class I genomic clone. Locus specificity of the probe appears to be derived primarily from a stretch of approximately 180 nucleotides comprising the last (7th) intron of the original B7 gene. Use of the probe to analyze Southern blots of genomic DNA from unrelated individuals provides the first direct demonstration of intragenic localization of an HLA allele-specific restriction endonuclease site. Availability of this probe should make practicable the study of HLA-B locus restriction fragment length polymorphism as genetic markers of disease susceptibility, and should provide a model for developing probes specific for other HLA class I loci.
...
PMID:An HLA-B locus probe clarifies endonuclease polymorphism of major histocompatibility complex class I genes. 609 60

A DNA sequence consisting of the 5-mer AGAGG repeated tandemly 32 times has been detected in a chicken genomic clone and found to be present in about 2000 copies per chicken genome. This sequence was highly susceptible to single-strand specific endonucleases isolated from Aspergillus oryzae (S1) and mung bean, but cleavage by a single-strand specific endonuclease isolated from Neurospora crassa occurred only at a pH below 5.5. Endonucleolytic cutting of the AGAGG sequence by the single-strand specific enzymes required a supercoiled substrate and was independent of ionic strength.
...
PMID:A chicken repetitive DNA sequence that is highly sensitive to single-strand specific endonucleases. 623 28

A genomic clone that contains the human gastrin gene was isolated from a human gene library. Restriction endonuclease mapping and DNA sequencing analysis revealed that this gene is about 0.7 kb long, and has an intron. The intron is located at a position that separates the coding region into the peptide region essential for biological activities of gastrin and the non-essential, N-terminal peptide region.
...
PMID:Molecular cloning of the human gastrin gene. 632 77

The cDNA encoding the gonadotropin-releasing hormone (GnRH) receptor has recently been cloned and characterized in several species, including human. To determine the structure of the gene encoding the human GnRH receptor, we have screened a human genomic library and isolated seven positive clones, using cDNA probes derived from a human pituitary cDNA library. The isolated genomic clone contains the entire protein coding region of the GnRH receptor which is distributed between three exons and spans over 18.9 kb. Sequence analysis and restriction endonuclease mapping revealed the presence of two introns of 4.2 and 5.0 kb, respectively, both located within the open reading frame, designating the human GnRH receptor gene to the intron-containing class of the G-protein coupled receptor superfamily. Genomic Southern blot analysis indicated the presence of a single copy of the gene encoding for the GnRH receptor within the human genome. Using DNA from human-hamster somatic hybrid cell lines, the GnRH receptor gene was assigned to human chromosome 4, by means of PCR. The present study represents the first report on the GnRH receptor gene and its partial characterization should facilitate further investigation of the mechanisms by which expression of this gene is regulated.
...
PMID:The human gonadotropin-releasing hormone (GnRH) receptor gene: cloning, genomic organization and chromosomal assignment. 795 84


1 2 Next >>

---