FIGURE 3 The activity gel result showing that Gcn5 has HAT activity. Macronuclear extracts of Tetrahymena show the expected HAT activity of p55 (lane 1). The gene for Gcn5 was cloned into an expression plasmid and then induced. The induced Gcn5 (60 kDa) protein has HAT activity (lane 2). Lane 3 shows the result for uninduced cells; lane 4, induced cells lacking the expression plasmid containing the Gcn5 gene. The numbers on the right indicate molecular mass in kilodaltons.