Many intracellular proteins are required to interact or bind to other macromolecules within a bind DNA. Such proteins often have conserved structural features, called motifs, whis at can cell in order to function properly. One class of such proteins is comprised of proteins tha interact with DNA. One such motif consists of two closely aligned a-helices(shown as cylinders below)that each have leucine-rich regions. This motif is referred to as a leucine
once oncu n a paiuicuia positon on DNA, a nucleosome remained fixed in place because of the tight association 30-nm 98A5 sequence-specific DNA-binding proteins nucleosome
