WHOLE CELL PROTEIN EXTRACTS
This if for both cytoplasmic and nuclear proteins-if you want only nuclear follow nuclear extract protocol.
- Lyse cells (1X107) in 1 ml. of the following buffer:
20 mM Tris pH 7.5
100 mM NaCl
0.5% NP-40
0.5 mM EDTA
0.5 mM PMSF
0.5% protease inhibitor cocktail (Sigma)
pipet cells up and down extensively and then sit on ice for 10 minutes.
- Spin down extracts full speed in microfuge for 10 minutes at 40C.
- Transfer supernatant carefully into a new tube.
- Perform Bio-Rad protein assay.
ALTERNATIVELY-FOR VERY INSOLUBLE (i.e. cytoskeletal proteins etc.)---
- Lyse 107-108 cells in 250-500 ml of cell extraction buffer by pipetting up and down and then sonicating briefly to shear DNA (microtip for about 10 sec.).
- Determine protein concentration using Pierce BCA Protein Assay.
- Load 20 mgs (small gel) or 100 mgs (large gel) of total lysate onto SDS-PAGE gel-Western blot if necessary.
Cell extraction buffer
20 mM Tris pH8.0
100 mM NaCl
1 mM EDTA
0.1% SDS
1 mM PMSF
1X protease inhibitor cocktail