Practice question

Reader domains distinguish modification state of histone tails to translate histone code into functional outcomes. SANT domains, named after Swi3, Ada2, N-Cor, TFIIIB, are structurally related to Myb DNA-binding motifs and found in co-repressor and remodeling subunits including SMRT, Ada2 and ISWI. Biochemical studies show SANT2 of SMRT and SANT of Ada2 preferentially bind unacetylated H3 and H4 tails, increasing affinity of associated deacetylase and acetyltransferase complexes for hypoacetylated substrates. Tetracetylation of H4 disrupts this interaction, illustrating sensitivity to modification status without direct recognition of methyl or acetyl marks.