the release of these four histones ( h2a , h2b , h3 , and h4 ) is coordinate and occurs in a highly cooperative manner , as indicated by ( 1 ) dependence of the initial kinetics of histone removal upon heparin concentration , ( 2 ) analysis of dna and histones in the fractions obtained from differential sedimentation of heparin-treated nuclei , and ( 3 ) analysis of the products from heparin-treated nuclei by equilibrium centrifugation in metrizamide density gradients .
C0019646
h2a
C0007610
nuclei