By differential sucrose gradient centrifugation of pig kidney chromatin in the presence or absence of Na-EDTA and under varying ionic strength conditions, three nucleosome-like subpopulations with different buoyant densities can be obtained. These particles, on the basis of their histones and HMG protein pattern, of the 5-methylcytosine level of their DNA and of the RNA polymerase activity associated with them, can be considered as originating from chromatin fractions differently involved in gene expression. Two-dimensional electrophoresis of the tightly-bound non-histone proteins shows a distinct pattern for each subpopulation, such protein components being notably present in restricted numbers but in high amounts in the subpopulation which was apparently derived from condensed heterochromatin.
Tightly-bound non-histone proteins in different nucleosome-like subpopulations from pig kidney chromatin / Caiafa, Paola; A., Tomassetti; S., Mastrantonio; Reale, Anna; M., Spinelli; Strom, Roberto. - In: CELL BIOCHEMISTRY AND FUNCTION. - ISSN 0263-6484. - STAMPA. - 6:1(1988), pp. 39-45. [10.1002/cbf.290060107]