Overall pathway of mononucleosome production.

Five electrophoretically distinguishable classes of mononucleosomes (MI, MII, ...MV) are produced upon treatment of mammalian nuclear chromatin with micrococcal nuclease. These five forms differ in their initial DNA lengths, relative mass proportions, stability, contents of histone H1, and presence of certain nonhistone proteins. A new "chromatin fingerprinting" technique has been developed in order to trace nuclease-mediated interconversions between these mononucleosomes and their polynucleosomal precursors. Application of this technique, together with earlier findings from this laboratory, has made possible the elucidation of the overall pathway of nuclease cleavage of chromatin which leads to the production and interconversion of these mononucleosomes, and has permitted reconstruction of the organization of these mononucleosomes in undigested chromatin...