Figure 9.—

Summary of differential effects of histone H3 and H4 mutations on transcriptional silencing and heterochromatin structure at HML. (A) Effects of histone H3 mutations on HML silencing (top) and chromatin structure measured with a DNA supercoiling based assay (bottom). The histone fold domains of H3 are indicated above the sequence, and the substitutions of specific residues are indicated below the sequence. The phenotypes of H3 mutations are color coded. (B) Effects of histone H4 mutations on HML silencing (top) and chromatin structure (bottom). The phenotypes of H4 mutations are color coded similarly to those of H3 mutations.