Immunoprecipitation buffer (IP buffer)

Reagent	Final concentration	Amount
Tris-HCl pH 8.0 (1 M)	20 mM	1 mL
KCl (1 M)	140 mM	7 mL
MgCl2 (1 M)	1.8 mM	0.1 mL
NP40 (10%)	0.1%	0.5 mL
Heparin (50 mg/mL)	0.2 mg/mL	0.2 mL
ddH2O	n/a	41.2 mL
Total	n/a	50 mL

Keep heparin stock solution aliquoted at −20°C; avoid repeated cycles of thawing and freezing. All other stock solutions can be kept at room temperature. Nonetheless, to be able to prepare a cold IP buffer at will, we recommend keeping stock solutions at 4°C, with the exception of NP40. Once prepared, keep IP buffer at 4°C until use.