Fig 7. Heterochromatin restricts access of proteasome to centromeric regions.

A, Cnp1-GFP level is increased in mts2-1 cells after incubation at 37°C for 4 hours. Western blotting was performed using an anti-GFP antibody. B, The association of proteasome with centromeres is increased in clr4Δ. ChIP assays were conducted with indicated cells expressing Mts2-myc using an anti-myc antibody. Data from ChIP with the myc antibody were normalized against those from IgG mock ChIP. cnt3, centromeric region. n = 8, error bar represents SEM. *, p<0.01. C, Model: heterochromatin mediates centromere specificity by blocking the access of ubiquitin-proteosome machinery to centromeres to prevent the degradation of CENP-A.