Chromatin fibers are made up of eukaryotic DNA found in the nucleus. Once considered a dull, static entity, a passive scaffold that supports many interesting cellular processes, chromatin structure is now known to be dynamic. It changes in an orchestrated way, responding to the interchange and modification of proteins that associate with and comprise it. At the heart of chromatin's design is the nucleosome, a complex of DNA wound around an octamer containing two molecules each of histone proteins H2A, H2B, H3, and H4.1
Chromatin's structure plays an important regulatory role in DNA template-dependent processes including transcription, replication, recombination, repair, segregation, chromosomal stability, cell cycle progression, and epigenetic silencing.1-3 Many factors can induce remodeling (changes in chromatin structure) including histone modification and the binding of numerous non-histone proteins that are loosely termed the transcriptional apparatus.
Histones contain two distinct domains. The proteins' amino-terminal tails, which protrude from the...
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