Preparation of Chromatin Assembly Extracts from Xenopus Oocytes

The majority of DNA in eukaryotic cells is packaged by histones and many poorly characterized nonhistone proteins to form a dynamic structure known as chromatin. Chromatin is a periodic structure made up of repeating, regularly spaced subunits, the nucleosomes. Elegant genetic experiments have clearly demonstrated that histones play a central role in transcriptional control (1 ). Moreover, histones, via protein-protein interactions or by playing an architectural role, can facilitate or inhibit the transcriptional activation process (1 ,2 ). It also appears that the function of histones themselves may be regulated by protein modifications and therefore may be targets for cell signaling pathways (3 ,4 ).