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 production of alpha-fetoprotein (AFP) and metallothionein-1 (MT-1) in mouse tissues follows a well-defined developmental pattern. The genes for these proteins are highly transcribed in embryo liver but transcribed at a very low rate in adult liver and in brain at all stages of development. A dot hybridization procedure was defined for quantitative screening for AFP, MT-1, immunoglobulin, and satellite DNA sequences to determine the relative degree of micrococcal nuclease sensitivity of these DNA sequences in fetal, newborn, and adult liver and brain, and the visceral yolk sac of the embryo. It was found that, for the DNA sequences assayed, three distinct chromatin conformations exist. DNA that does not code for protein (satellite DNA) was highly resistant to nuclease cleavage. DNA that codes for protein, but is not available for transcription (unrearranged immunoglobulin (C mu) genes in brain, liver, and yolk sac) was fourfold more sensitive to cleavage than were satellite DNA sequences. A further sevenfold increase in nuclease sensitivity was detected in genes actively being transcribed (MT-1 and AFP genes in embryo liver). Quiescent MT-1 and AFP genes were intermediate in nuclease-sensitivity between active genes and unrearranged C mu genes. These data indicate that MT-1 and AFP genes are permanently established in a nuclease-sensitive chromatin conformation early in liver development, and that conformation is maintained regardless of the degree of transcription of the genes. A second, reversible change in chromatin structure occurs in step with changes in the degree of developmentally regulated expression of AFP and MT-1 genes.
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PMID:Nuclease sensitivity of alpha-fetoprotein, metallothionein-1, and immunoglobulin gene sequences in mouse during development. 243 93

We have investigated the stability of the higher order structure of chromatin associated to genes which display a different transcriptional activity in adult rat live. Nuclei were digested with micrococcal nuclease and chromatin was fractionated by sedimentation in sucrose gradients. Specific DNA sequences were revealed by dot-blotting. In conditions of physiological ionic strength the distribution of the inactive gamma-casein gene sequences is similar than the bulk of chromatin. In the same conditions the relative content of the albumin gene, highly expressed in adult rat liver, revealed an enhanced instability of the chromatin superstructure. The distribution of the potentially active but silent alpha-fetoprotein sequences in adult liver showed an intermediate unfolding of its chromatin superstructure. These distinct behavior was not observed in non-physiological ionic strength conditions. Our results suggest that distinct folding of the local higher order structure of chromatin actually occurs in the region of active, potentially active and inactive genes.
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PMID:Differential stability of the higher order structure of chromatin associated with genes having different transcriptional activity. 244 Apr 33

The resolution of the standard micrococcal nuclease assay for sensitivity of active chromatin has been enhanced by the inclusion of an additional step of digesting nuclease-digested DNA with a suitable restriction enzyme prior to Southern hybridization. The improved assay has been used to analyze the chromatin structure of the lamin A, albumin and alpha-fetoprotein genes during rat liver development.
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PMID:An improved method to distinguish micrococcal nuclease sensitivity of chromatin. 890 69