Histones characteristics

In the circulation of the BN rat there is a simultaneous and transient presence of antiglomerular basement membrane antibodies and circulating immune complexes [175]. Another characteristic is a striking increase in total and antigen-specific IgE level [190], which also has been found in Hooded Lister rats [ 191 ], as well as anti-single-stranded DNA antibodies [ 181] in the BN rat. In PVG/C rats [192, 193], mercuric chloride also induced glomerulopathi and antinuclear antibodies directed against non-histone nucleoprotein. 

The fluorescence of purified histones has been studied by several different groups, 90 95) with the most detailed studies being on calf thymus histone HI. Histone HI, which binds to the outside of core particles, contains one tyrosine and no tryptophan. This protein exhibits a substantial increase in fluorescence intensity in going from a denatured to a folded state.<90) Collisional quenching studies indicate that the tyrosine of the folded HI is in a buried environ-ment.(91) Libertini and Small(94) have identified three emissions from this residue when in the unfolded state with peaks near 300, 340, and 400 nm. The 340-nm peak was ascribed to tyrosinate (vide infra), and several possibilities were considered for the 400-nm component, including room temperature phosphorescence, emission of a charge transfer complex, or dityrosine. Dityrosine has the appropriate spectral characteristics, but would require... 

The fact that nucleosome-like particles can be reversibly reconstituted from histones and DNA, without any additional factor, exemplifies the principle of self-assembly of biological structures. The reconstituted particles have the characteristic beaded appearance of nu-... 

Parseghian MH, Hamkalo BA (2001) A compendium of the histone HI family of somatic subtypes an elusive cast of characters and their characteristics. Biochem Cell Biol 79 289—304 Pehrson JR, Fuji RN (1998) Evolutionary conservation of histone macroH2A subtypes and domains. 

HD In Drosophila models of Huntington s disease, the HDAC inhibitors SAHA and sodium butyrate arrest the progressive neuronal degeneration and lethality (Steffan et al, 2001). SAHA and sodium butyrate have also been demonstrated to extend survival, ameliorate motor deficits and delay characteristic neuropathology in the mouse Huntington s disease model, R6/2 (Ferrante et al, 2003 Hockly et al, 2003). In NaBu-treated animals, animals displayed enhanced acetylation status of histones and pro-survival transcription factors like Spl and reduction in several neuropatho-logical hallmarks like striatal neuronal atrophy (Ferrante et al, 2003). Consistent with the idea that HDAC inhibition relieves transcriptional repression and that protection is downstream of mutant htt, neither SAHA nor sodium butyrate decreased mutant htt expression or aggregates (Ferrante et al, 2003 Hockly et al, 2003). 

Despite many biochemical similarities between linker and core histones the proteins of these two groups differ in architecture, evolutionary origin, and function. Each of the four core histones has a characteristic histone fold domain. The latter is an old and ubiquitous structural motif used in DNA compaction and protein dimerization [3]. Linker histones do not have a histone fold. The canonical... 

Fig. 3. Amino acid sequence of several somatic human histone HI proteins to illustrate the microheterogeneity of linker histones. The sequences for human histone HI variants (H1.1-H1.4) were obtained from Ref [373] and Hl-5 was from Ref [412]. The nomenclature followed for the designation of these histone variants was Doenecke (e.g., see Ref. [412]). The nomenclature of Parseghian et at. [373] is shown in parentheses. The regions corresponding to the trypsin-resistant (winged helix motif [96]) which is characteristic of the protein members of the histone HI family are indicated by a boxed inset.

Because these nucleases preferentially solubilize the DNA of active genes, methods have been developed to examine the proteins associated with the DNA. These methods take advantage of two main characteristics of the chromatin from active genes, its solubility in 100 mM NaCl and its solubility in moderate concentrations of Mg " " (2-5 mM). What has been found is that all four of the core histones H2A, H2B, H3, and H4 are present in these solubilized fractions [36-38]. Histone HI is... 

Using the unique characteristics of the procaryotic polymerases, a number of investigators have attempted to define what happens to the histones during transcription. In the mid 1980s two different laboratories did a set of important experiments. Lorch et al. [84] observed that during transcription with SP6 RNA polymerase of a DNA that contained an SP6 promoter, flanked by DNA sufficient... 

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