Partial inhibition of histone deacetylase in active chromatin by HMG 14 and HMG 17.

Digestion of isolated Friend erythroleukemic cell nuclei with DNase I under conditions which selectively destroy the DNA of transcriptionally "active" genes releases into the supernatant fraction proteins of the non-histone "High Mobility Group" (HMGs). Two of these, HMG-14 and HMG-17(identified by solubility in trichloroacetic acid, electrophoretic mobility on SDS-polyacrylamide gels and by amino acid composition) will partially inhibit the endogenous mouse cell histone deacetylase enzymes when added to in vitro assay mixtures. Other closely related proteins do not share this inhibitory ability and thus the reaction with the enzymes appears to be specific. Since these two HMG proteins appear to be preferentially associated with the "active" fraction of chromatin, these findings have important implications for possible models of eukaryotic gene regulatory mechanisms.