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)

Hybridization experiments show that DNA extracted from two distinct subsets of mononucleosomes (MNI and MN2) generated by a limited action of micrococcal nuclease on trout testis nuclei is enriched approximately 7-fold in sequences that are transcribed into cytoplasmic polyadenylated RNA in trout testis cells. Both subsets of mononucleosomes contain eight core histones, but MNI also possesses one or two molecules of a small, basic, high-mobility-group (HMG) protein H6 [Levy W., B., Connor, W. & Dixon, G. H. (1979) J. Biol. Chem. 254, 609-620], bound to a DNA fragment of 140 base pairs. In contrast, MN2 contains 1 molecule of H1 but no H6, and its DNA length is somewhat longer at 140-190 base pairs. The preferential release of these two subsets of mononucleosomes is correlated with the presence of a second larger HMG protein, HMG-T, in the linker regions flanking both types of mononucleosomes. The HMG-T-containing linker regions appear to be considerably more susceptible to attack by micrococcal nuclease than H1-containing linkers. Cross-reassociation reactions between the DNA from MN1 and MN2 subsets indicate that they share a significant extent of sequence overlap but also that each subset contains specific sequences that are absent in the other subset.
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PMID:Limited action of micrococcal nuclease on trout testis nuclei generates two mononucleosome subsets enriched in transcribed DNA sequences. 28 7

Rat liver chromatin was digested by micrococcal nuclease. Chromatin subunits (or mononucleosomes) were isolated by sucrose density gradient and subsequently fractionated by 6% polyacrylamide gel electrophoresis into two major components. One component (MN1) of the mononucleosomes had a higher mobility, contained histones H2A, H2B, H3, H4, and shorter DNA fragments (140 base pairs) while the other (MN2) contained all five histones and longer DNA fragments (180 base pairs). Both submononucleosomes (MN1 and MN2) were found to contain nonhistone chromatin proteins (NHCP). By electrophoresis in 15% sodium dodecyl sulfate-polyacrylamide gel, 9 and 11 major fractions of NHCP were identified in the submononucleosomes MN1 and MN2, respectively. It was also observed that treatment of mononucleosomes with 0.6 M NaCl removes most of these NHCP and histone H1 except for two major NHCP which remain in the core particles.
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PMID:Identification of nonhistone chromatin proteins in chromatin subunits (or mononucleosomes) devoid of histone H1. 47 14

Mononucleosomes (MN1) enriched in structural non-histone proteins and transcribed DNA sequences were obtained by limited digestion of trout testis nuclei with micrococcal nuclease followed by selective solubilization in 0.1 M NaCl. These monosomes consist of the four inner histones plus stoichiometric amounts of the non-histone protein H6, of the HMG group, complexed with 140 base pairs of DNA. Hybridization experiments indicate that MN1 DNA is enriched in sequences complementary to cytoplasmic polyadenylated RNA.
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PMID:Partial purification of transcriptionally active nucleosomes from trout testis cells. 56 93

Hen erythrocyte chromatin was digested with staphylococcal nuclease and fractionated by electrophoresis in polyacrylamide gels. Instead of the three bands described for mouse carcinoma chromatin, four main discrete components (MN1, MN2, MN2E and MN3) were resolved in the mononucleosome fraction of erythrocyte chromatin. MN2 contained all five histones and a DNA fragment of 165--180 base pairs. MN2E comprised four nucleosomal histones plus histone H5 (but not H1) and a DNA fragment of 170--190 base pairs. The relatively nuclease resistant MN3 fraction of erythrocyte nucleosomes contained H1 but no H5 histone. A more accurate analysis of the MN2 fraction in mouse carcinoma nucleosomes revealed some additional microheterogeneity depending on the presence of two different subfractions of H1.
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PMID:Separation of nucleosomes containing histones H1 and H5. 73 86

Mononucleosomes greatly enriched in non-histone proteins were prepared by limited digestion of testis nuclei with micrococcal nuclease. Five to fifteen per cent of the chromatin was solubilized and could be separated by adjustment to 0.1 M NaCl, into a soluble fraction MN1, consisting of mononucleosomes containing the four inner histones and the small basic non-histone, H6, associated with a 140-base-pair DNA fragment. H1 was notably absent in MN1. The fraction insoluble in 0.1 M NaCl (MN2) comprised a mixture of mono-, di-, tri-, and oligosomes. MN2 monosome fraction contained the four inner histones plus H1 and lacked H6 and the length of its DNA was 170 base-pairs. Previous work had shown that limited micrococcal nuclease digestion of trout testis nuclei released a great proportion of the non-histone protein, high mobility group protein T (HMG-T). It seems likely that HMG-T is the major non-histone protein located in the linker regions of a subset of nucleosomes containing the non-histone protein H6 as a major structural component. Moreover, the presence of HMG-T renders this subset of nucleosomes very sensitive to micrococcal nuclease. Hybridization experiments were performed to demonstrate that the DNA from MN1 monosomes corresponds to a subset of the trout testis genome. This DNA subset is greatly enriched in sequences that are present in cytoplasmic RNA. Chromatin subunits enriched in their content of H6 and HMG-T could also be obtained by limited digestion of trout testis chromatin with DNase II followed by precipitation with MgCl2.
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PMID:A subset of trout testis nucleosomes enriched in transcribed DNA sequences contains high mobility group proteins as major structural components. 76 85

Three major satellite DNAs comprise 40-45% of the genome of Drosophila virilis. Since these satellites are not substrates for most restriction enzymes, we were able to digest D. virilis nuclei with HaeIII and micrococcal nuclease and isolate chromatin fractions containing variable levels of satellite DNA. Electrophoretic analysis of these chromatin fractions revealed that the level of the acid-soluble chromosomal protein, cp17.3, was directly related to the percentage of satellite DNA in chromatin. The correlation between cp17.3 and satellite DNA abundance suggests that cp17.3 is involved in the heterochromatic condensation of satellite DNAs. cp17.3 occurs at a frequency of one molecule per 10-20 nucleosomes. It is detected in an electrophoretically distinguishable class of mononucleosomes, provisionally identified as MN1uH2A, which contains ubiquitinated histone H2A (uH2a) but lacks histone H1. It is not detected in MN1, a second class of mononucleosomes, which lacks uH2A and H1. Since cp17.3 is correlated with satellite DNAs and present in nucleosome cores, it might be a histone variant specifically associated with satellite DNAs.
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PMID:Satellite DNA-correlated nucleosomal proteins in Drosophila virilis. 300 8

The protein composition of nucleosome fractions differing in their sensitivity to micrococcal nuclease and derived from butyrate-treated or untreated HeLa cells has been compared. Most of the high-mobility-group-14 (HMG-14) and HMG-17 content of HeLa cell chromatin is associated with those nucleosomes that are preferentially sensitive to micrococcal nuclease. Furthermore, electrophoresis of these two HMG proteins from the transcriptionally active chromatin fraction MN1 of butyrate-treated cells resolves them into a series of bands. The multiple band pattern of HMG-14 and -17 from butyrate-treated cells results from hyperphosphorylation rather than hyperacetylation. Phosphorylation of these two small nonhistone proteins may play some role in the modulation of the structure of transcriptionally active chromatin.
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PMID:Enhanced phosphorylation of high-mobility-group proteins in nuclease-sensitive mononucleosomes from butyrate-treated HeLa cells. 645 41

Limited micrococcal nuclease action on trout testis nuclei yields two mononucleosome subsets, MN1 and MN2, enriched in transcribed DNA sequences. MN1 is soluble and MN2 insoluble in 0.1 M NaCl. Electrophoresis of intact MN1 and MN2 mononucleosomes in 4% polyacrylamide gels shows that each fraction is heterogeneous and four major and several minor subcomponents can be resolved. Dissociation of the protein components of these nucleosomal particles by two-dimensional electrophoresis shows that the major component of MN1 possesses stoichiometric amounts of the four inner histones and of the high mobility group protein H6, associated with DNA fragments of 140 base pairs in length. The major component of MN2 possesses equimolar amounts of the four inner histones plus 1 molecule of H1 and H6, complexed with DNA fragments of 220 base pairs in size.
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PMID:Transcriptionally active mononucleosomes from trout testis are heterogeneous in composition. 735 38