Butyrate-induced histone hyperacetylation in human and mouse cells: estimation of putative sites of histone acetylation in vivo.

Human and mouse cells in culture were treated with various concentrations of sodium butyrate. Acid-extracted histones of control and butyrate-treated cells were analyzed by two-dimensional gel electrophoresis. All core histones of the control cells contained modified forms. All core histones of the butyrate-treated cells were hyperacetylated. Depending on the number of acetylation sites per molecule, each histone or histone variant exhibited a characteristic number of acetylated forms. This number was the same for each histone common in human and mouse cells treated with butyrate. Histones 2A.1, 2A.2, and 2A.X have two sites of inner acetylation; 2A.Z has 3; 2B's have 5; and each one of the H3 variants as well as H4 have 4.