When DNA is tightly bound with histones,
   the  heterochromatin that os formed is inaccessible to enzymes such as
   DNAse as well as RNA polymerase II.

   Chromatin remodeling involves transcriptional activators

   in  eukaryotic  chromosomes  is  combined with histones and nonhistone
   proteins  to  form  chromatin.  Some  chromosomal  regions  are highly
   condensed in the interphase nucleus and form transcriptionally inert .
   Investigators have shown that genes in transcriptionally inert regions
   of  the  genome  are  relatively  resistant to in vitro digestion with
   DNAse I. Euchromatic regions on the other hand, have an open chromatin
   configuration,  and are sensitive to DNAse I digestion. Genes in these
   regions  can  be  transcribed.  Nucleosomes can inhibit multiple steps
   required for gene transcription.

   The  binding  of  enhancer  transcription  factors  requires accessing
   nucleosomal DNA and may result in displacement of the nucleosome.