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. 1999 Mar;19(3):2061–2068. doi: 10.1128/mcb.19.3.2061

FIG. 2.

FIG. 2

The H2A/H4 nucleosomal HAT activity in Tetrahymena is not p55 dependent. (A) HAT activity of RP-HPLC fractions following reconstitution by stepwise dialysis. A peak of free, nonnucleosomal HAT activity (I*) was contained in fraction 2. In contrast, a well-separated peak of nucleosomal HAT activity was contained in fractions 5 to 7 (II*). (B) Substrate specificity of these fractions. Note that nucleosomal HAT activity (II*) was H2A/H4 specific; in contrast, free-histone HAT activity was H3 specific. (C) Western blot analysis of the fractions. As expected, free-histone HAT activity (I*) (fractions 2 and 3) contained essentially all of the p55 signal. In contrast, the peak of nucleosomal H2A/H4 HAT activity (fractions 5 to 7) was devoid of p55, suggesting that this polypeptide cannot be responsible for the nucleosomal H2A/H4 HAT activity (see text). Note that fractions 2 and 3 also contained the majority of Ada5/Spt20 signal. Lane C contains DNase I extract as input.