Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.1.30.2 (endonuclease)
 18,621 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The DNA coding for histones from Strongylocentrotus purpuratus, purified up to 100-fold with the use of Hg+2-CS2-SO4 and actinomycin-CsC1 equilibrium density gradients, has been used to study the clustering of genes coding for different histones and the size of the repeating multigene cluster. When digested with EcoRI restriction endonuclease, the histone DNA is identified in two classes of fragments with molecular weights of 1.15 X 106 and 2.8 X 106, whereas after treatment of the DNA with HindIII restriction endonuclease, histone gene sequences can be identified only in a fragment of 3.95 X 106. Treatment of the DNA with both enzymes simultaneously shows that there is a HindIII site within the smaller EcoRI fragment. Partial digests with HindIII give fragment sizes that appear to be simple multiples of a 3.95 X 106 repeat. Individual histone mRNAs all hybridize to the 3.95 X 106 fragment but only to one or the other EcoRI fragments. The evidence strongly suggests a repeating unit of 3.95 X 106 containing the genes for most, if not all, the histonrs.
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PMID:Histone gene arrangement in the sea urchin, Strongylocentrotus purpuratus. 110 3

Cytosine methylation of developmentally regulated genes of the sea urchin Strongylocentrotus purpuratus was studied by using restriction-endonuclease digestion and Southern blotting. The single-copy bindin gene, the family of five cytoplasmic actin genes and the 400-fold-repeated set of five early histone genes were mostly unmethylated, but some sites exhibited partial methylation that varied throughout development. This shows that in echinoderms the methylation of DNA is not confined to the non-transcribed portion of the genome, as previously believed [Bird, Tagart & Smith (1979) Cell 17, 889-901], and may play a role in transcriptional regulation.
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PMID:DNA methylation pattern changes during development of a sea urchin. 159 Jul 64

The developmentally regulated sea urchin early histone gene repeat (SUEHGR) from Strongylocentrotus purpuratus was isolated as chromatin by nucleoprotein hybridization. This technique is a novel method to isolate specific sequences as chromatin. Because the purification scheme is based only on the gene sequence and is independent of other physical properties such as protein composition and transcriptional activity, we were able to isolate the same gene in different functional states. Gene size chromatin fragments were solubilized by restriction endonuclease digestion of cell nuclei. Using T7 gene 6 exonuclease, the 3'termini of the fragments were exposed and then hybridized in solution to a biotinylated oligonucleotide complementary to one end of the SUEHGR fragment. The hybrids were bound to an Avidin D matrix. DTT cleavage of the biotin linker yielded a chromatin fraction greater than 700 fold enriched in SUEHGR. Overall yields were between 2% and 15%. The purity of the isolated material was independently measured to be greater than 80%. The homogeneous native structure of the inactive genes was preserved as shown by electron microscopy and micrococcal nuclease digestion of the purified SUEHGR. Minor heterogeneity was observed for the purified active genes by micrococcal nuclease digestion but the main features of the active chromatin were preserved during isolation. This isolation offers the first opportunity to study the structure of an RNA polymerase II gene at different stages of the cell cycle and development.
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PMID:Nucleoprotein hybridization: a method for isolating active and inactive genes as chromatin. 203 Sep 47