Histone extraction

1. Harvest cells washing 2X with PBS (PBS can be supplemented with 5mM sodium butyrate to retain histone acetylation)

2. Resuspend cells in Triton Extraction Buffer (TEB: in PBS, 0.5% Triton, 2mM PMSF, 0.02% NaN3) 1ml per 107 cells (roughly 500ml)

3. Lyse cells on ice with gentle stirring

4. Centrifuge 2000rpm 10 min 4°C. Remove and discard supernatant.

5. Wash cells with half volume TEB (roughly 250ml) and centrifuge as before.

6. Resuspend cells in 0.2N HCl at 4x107 cells per ml (roughly 200ml)—extract o/n at 4°C.

7. Centrifuge samples at 2000rpm 10 min 4°C.

8. Remove supernatant and measure protein concentration

9. Store aliquots at -20°C.