Regulates silencing of the mat2 and mat3 loci. Organizes the chromatin structure of the mating-type region where it also participates in establishing the 'cold spot' for recombination. Required for proper positioning of nucleosomes at heterochromatic loci and for transcriptional gene silencing (TGS) function of the Snf2/Hdac-containing repressor complex (SHREC). Interacts with clr3. Associates with major heterochromatin, centromeres, sub-telomeres, rDNA and the mat locus.