Chromatin protein

While studying the binding of mercury by chromatin of rats injected with mercuric chloride, the nonhistone chromatin proteins in rat and kidney cell nuclei were shown to be mainly responsible for the mercury deposition [43]. The mercury-binding nonhistone proteins were found to be heterogeneous by sodium dodecyl sulphate-polyacrylamide gel electrophoresis. 

Nickel chloride has been reported to induce DNA strand breaks in CHO cells [435] in a concentration, which did not significantly injure normal cellular division, and DNA-protein cross-links, which were concentration- and time-dependent and preferentially occurred in cells in the late S phase of the cell cycle [436], The nickel cross-linked proteins included nonhistone chromatin proteins, nonhistone DNA-binding proteins and a 30 kDa protein that comigrated electrophoretically with histone HI. Moreover, blocking of cell growth in S phase [249] and induction of DNA repair synthesis in CHO cells [437] and reduction in the fidelity of DNA synthesis [438, 439], have been reported. 

Surprisingly, C. elegans appears to have lost a considerable number of chromatin proteins from the Polycomb group of proteins, observed in Drosophila and in mammals, although other transcription factor genes... 

In addition to its role in the covalent modification of chromatin proteins, PARP-1 also functions as a nucleosome-binding protein and, hence, a structural component... 

PARP-1 is an abundant ( 1 to 2 million molecules per cell) and ubiquitous nuclear protein that plays important roles in a variety of cellular functions. One aspect of PARP-1 biology is the modulation of chromatin structure through direct nucleosome binding, covalent modification of chromatin proteins, or the production of PAR which can serve as a polyanionic matrix for the binding of chromatin proteins. Given its role in a variety of physiological and pathophysiological processes, PARP-1 has... 

Yaneva J, Leuba SH, van Holde K, Zlatanova J (1997) The major chromatin protein histone HI binds preferentially to cis-platinum-damaged DNA. Proc Natl Acad Sci USA 94(25) 13448-13451... 

The functions of these fusion proteins and their precise roles in the induction of cancer are currently the subject of intense investigation (Collins et al., 2006 Huntly et al., 2004 Kindle et al., 2005). In general, it appears that since the proteins are fused in-frame, their catalytic domains continue to function, but these activities are mis-directed by the targeting domains of their fusion partners. The result is aberrant acetylation of chromatin and non-chromatin proteins, as well as sequestration of key nuclear regulators. These mechanisms are discussed in-depth in Chapter 8 of this book. Furthermore, two recent studies have demonstrated that wild-type MOZ is essential for development of hematopoietic stem cells (Katsumoto et al., 2006 Thomas et al., 2006). This suggests that AML may arise not only due to the aberrant activity of the fusion proteins, but also due to the loss of their original function. 

Reuter G, Spierer P (1992) Position effect variegation and chromatin proteins. Bioessays 14 605—612 Rice JC, Briggs SD, Ueberheide B, Barber CM, Shabanowitz J, Hunt DF, Shinkai Y, Allis CD (2003) Histone methyltransferases direct different degrees of methylation to define distinct chromatin domains. Mol Cell 12 1591-1598... 

An, W., van Holde, K., and Zlatanova, J. (1998) The non-histone chromatin protein HMGl protects linker DNA on the side opposite to that protected by linker histones. J. Biol. Chem. 273, 26289-26291. 

Scaffidi, P., Misteli, T., and Bianchi, M.E. (2002) Release of chromatin protein HMGBl by necrotic cells triggers inflammation. Nature 418, 191-195. 

Boonyaratanakornkit, V., Melvin, V., Prendergast, P., Altmann, M., Ronfani, L., Bianchi, M.E., Taraseviciene, L., Nordeen, S.K., Allegretto, E.A., and Edwards, D.P. (1998) High-mobility group chromatin proteins 1 and 2 functionally interact with steroid hormone receptors to enhance their DNA binding in vitro and transcriptional activity in mammalian cells. Mol. Cell. Biol. 18, 4471 487. 

Elton, T.S. (1986) Purification and Characterization of the High Mobility Group Nonhistone Chromatin Proteins. Ph.D. Thesis, pp. 1-134. Washington State University, Pullman, WA 99164. Palvimo, J. and Linnala-Kankkunen, A. (1989) FEBS Lett. 257, 101-104. 

Chadwick, B.P. and Willard, H.F. (2001) A novel chromatin protein, distantly related to histone H2A, is largely excluded from the inactive X chromosome. J. Cell Biol. 152, 375-384. 

Oraumbo IF, Van Duuren BL. 1987. Time-related binding of the hepatocarcingon carbon tetrachloride to hepatic chromatin proteins in vitro. Carcinogenesis 8 855-856. 

Complex multicellular eukaryotes differentiate irreversibly so that different cell types express a different profile of genes. Genes that are expressed are usually associated with swollen chromatin. Proteins found in active regions of the genome show characteristic modifications. 

It should be noted that zinc deficiency in E. gracilis, which affects the metabolism of the RNA polymerases and DNA also results in the modification in type and amount of the chromatin proteins. All the histones are absent in stationary phase cells.347... 

Steroid receptors control gene expression in target cells. An understanding of the molecular interactions between receptors and specific nuclear components is crucial for elucidating the mechanism of hormone action. Receptor binding to at least three structural elements of nuclei has been described. These include the nuclear matrix, nucleoacidic chromatin proteins (acceptor proteins), and specific DNA sequences in 5 upstream elements of hormone responsive genes. 

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