Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.1.31.1 (micrococcal nuclease)
 2,818 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The synthesis of rabbit alpha and beta globins under various conditions was studied using intact reticulocytes and reticulocyte cell-free systems. Raising salt concentration of media in which reticulocytes were incubated with radioactive amino acids reduced the total protein synthesis but did not affect the ratio of alpha to beta globins produced. Using a reticulocyte lysate which had been incubated with micrococcal nuclease to remove the endogenous globin messenger RNA activity, it was found that unlike the intact cell or the untreated lysate very little alpha globin was synthesised on adding purified globin mRNA. These results are discussed in terms of their compatibility with some proposed models of coordination of alpha and beta globin production.
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PMID:Maintenance of the ratio of alpha and beta globin synthesis in rabbit reticulocytes. 92 89

An 80S initiation complex was formed by incubating a heterologous cell-free system with 125I-labeled globin mRNAs in the presence of sparsomycin. The 80S initiation complex was then digested with micrococcal nuclease. The ribosomal 5S-RNA X L5-protein (5S RNP) fraction, released by EDTA treatment, contained 125I-labeled mRNA fragments. The attachment of labeled mRNA fragments to 5S RNP was shown by (a) CsCl isopycnic centrifugation, (b) recentrifugation through a sucrose density gradient and (c) acrylamide gel electrophoresis of 5S RNP purified by (b). Labeled fragments were released from 5S RNP by treatment with sodium dodecyl sulfate or pronase, indicating the participation of protein L5 in the attachment. The attached mRNA fragments were 23-25 nucleotides in length. Hybridization experiments, using restriction fragments of cDNA for rabbit beta globin mRNA, showed that the attached mRNA fragments were derived from the 5' portion of globin mRNAs. The attachment of 125I-labeled mRNA fragments to 5S RNP was also observed in the 80S initiation complex formed by incubation of reticulocyte lysate with 125I-labeled globin mRNA, but not in labeled polysomal fractions. These findings may indicate that 5S RNP interacted with the 5' portion of globin mRNA, containing the translation initiation codon of globin mRNA in the 80S initiation complex. The biochemical significance of these results is discussed.
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PMID:Attachment of the 5'-terminal portion of globin mRNAs to 5S-RNA X L5-protein in the 80S initiation complex. 384 Apr 35

The 15s globin mRNA-protein complex (mRNP) was isolated from chicken reticulocyte polyribosomes dissociated in EDTA. To determine protein binding sites, the mRNP was treated with micrococcal nuclease and the nuclease resistant RNA was mapped to the beta globin gene at the nucleotide level. As far as we can determine there is no bound protein from the Cap site to the poly A addition site of beta globin mRNA in the mRNP except for a short area in the coding region near the translation initiation site.
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PMID:Chicken reticulocyte polysomal messenger RNA-protein complex: absence of bound proteins in most of the coding region of beta globin mRNA. 646 16

Acetylation of specific lysine residues in the N-terminal domains of core histones is a biochemical marker of active genes. To determine the spatial and temporal distribution of this reversible posttranslational modification, affinity-purified polyclonal antibodies recognizing the epitope epsilon-acetyllysine have been used in immunoselection procedures with mononucleosomes and salt-soluble chromatin fragments generated by micrococcal nuclease. The DNA of the antibody-selected chromatin was slot-blotted and probed with a variety of gene sequences: an enhanced hybridization signal, with respect to that from the DNA of the input chromatin, demonstrated elevated acetylation levels on the histones associated with the probing sequences. Using chicken embryonic erythrocytes as chromatin source and probes from the beta globin locus, it was shown that both the embryonic epsilon and adult beta genes are acetylated at 5 and 15 days, and the acetylation uniformly covers the whole of the locus, precisely comapping with the 33 kb of open chromatin structure. Studies with proliferating human K562 cells show that the inactive but poised PDGF-beta gene is already hyperacetylated and that its acetylation status is not enhanced on induction. These results indicate that acetylation is not a consequence of transcription but a prerequisite and that it may be responsible for either generating or maintaining the open structure of poised and active genes.
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PMID:Chromosomal mapping of core histone acetylation by immunoselection. 916 94