Histones association with acidic proteins

In the absence of ligand, some nuclear hormone receptors associate with co-repressors, namely, SMRT (silencing mediator of retinoic acid and thyroid hormone receptors) and N-CoR (nuclear receptor co-repressor). Both, SMRT and N-CoR, recruit coregulatory protein SINS and histone deacetylases (HDACs) to form a large co-repressor complex that contains histone deacetylase activity, implicating histone deacetylation in transcriptional repression [52,53]. 

The DNA of cells containing nuclei (eukaryotic cells) is tightly associated with proteins called histones, most of which are rather basic proteins (i.e., they have high isoelectric points). Considering the basic character of most histones and the amino acids that contribute to this basic character, what enzymes would probably be most effective in disrupting histones from eukaryotic cellular DNA Would you expect the procedure used in this experiment for the isolation of bacterial DNA to be useful for the isolation of DNA from eukaryotic cells ... 

Histones Proteins containing a large number of positively charged amino acids (lysine, arginine) that associate with DNA to form nucleosomes. 

Histones are abnndant proteins associated with eukaryotic DNA and are a family of basic proteins rich in the positively charged amino acids lysine and/or arginine, which interact with the negative charges of DNA. 

The most abundant proteins associated with eukaryotic DNA are histones, a family of small, basic proteins present In all eukaryotic nuclei. The five major types of histone proteins—termed HI, H2A, H2B, H3, and H4 are rich In pos Itively charged basic amino acids, which interact with the negatively charged phosphate groups in DNA. 

Histones are a class of DNA-binding proteins that includes five types of protein. Their properties are outlined in Table 28.1. All histones are small, very basic proteins rich in lysine and arginine. Some have been remarkably well conserved in amino acid sequence throughout evolution. Histone H4, for example, shows only two substitutions between humans and peas and only eight substitutions between humans and yeast. The histones are the basic building blocks of chromatin structure. The nucleoids of prokaryotic cells also have proteins associated with DNA, but these proteins are quite different from the histones and do not seem to form a comparable chromatin structure. Thus, a histone-containing chromatin structure is a uniquely eukaryotic feature. In all kinds of eukaryotic nuclei, the histones are present in an equal weight amount with DNA, and histones H2A, H2B, H3, and H4 are always found in equimolar quantities. 

Histone acetylase activity has been associated with a number of transcription factors and co-activators. The proteins ACTR (activator of the thyroid and retinoic acid receptor) and SRC-1 (steroid receptor co-activator) are involved in activation of transcription by several ligand-bound nuclear receptors, and both contain histone acetylase activity. TAF250, a component of TFIID, also contains histone acetylase activity, as does the co-activator p300/CBP (CREB binding protein), which interacts with the transcription factor CREB. 

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