Subnucleosome particles containing high mobility group proteins HMG-E and HMG-G originate from transcriptionally active chromatin.

Subnucleosome particles SN2 and SN3 containing short DNA fragments and non-histone proteins of the high mobility group, HMG-G and HMG-E respectively, were purified from the chromatin preparations of mouse L cells partially digested with staphylococcal nuclease. Labeled DNAs prepared from these particles were hybridized to an excess of nuclear RNA. The binding of subnucleosomal DNA was about 3-fold higher comparing to total cellular DNA fragmented to the same size. Special control experiments showed that DNA.protein complexes present in subnucleosomes SN2 and SN3 preexisted in nontreated nuclei. The conclusion has been drawn that non-histone proteins HMG-G and HMG-E are associated with the DNA of transcriptionally active chromatin and are released by nuclease as subnucleosomes.