Procedure
Note: All centrifugations should be done at 4°C.
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Lyse the cells on 10 cm plates using 500 μl of buffer. Scrape the cells from plates immediately and place in 1.5 ml eppendorf tube
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Then pass lysate through a 25 G needle 10 times using a 1 ml syringe.
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Leave on ice for 20 min.
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Centrifuge out the nuclear pellet (P1) at 720 G (3000 rpm) for 5 min.
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Wash the nuclear pellet once again by adding 500 μl of fractionation buffer again.
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Disperse the pellet with a pipette and pass through a 25 G needle 10 times.
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Centrifuge again at 3000 rpm for 10 min.
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Remove the wash buffer, and resuspend the nuclear pellet in the nuclear buffer (standard lysis buffer with 10% glycerol and 0.1% SDS).
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Sonicate the nuclear pellet briefly for 3 sec on ice.
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Remove the supernatant and place in a fresh labeled eppendorf tube.
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Centrifuge the supernatant again at 8000 rpm for 20 min.
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Remove the supernatant again. This is the cytosolic and membrane fraction.
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If the mitochondrial fraction is desired, save the pellet from step 6, wash as with the nuclear pellet and resuspend in the same buffer as above.
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For a membrane fraction, Centrifuge the supernatant in an ultracentrifuge.
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Centrifuge at 40,000 rpm for 1h.
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Wash this pellet by adding 400 μl of the fractionation buffer to the pellet.
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Resuspend by pipetting. Use a 25 G needle as above.
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Then re-centrifuge for 45 min.
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Resuspend the membrane pellet in the same buffer as used for the nuclei.
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Optional : Concentrate the supernatant by centrifuging through the filter unit. This should concentrate the cytosol down to approximately 50 - 75 μl.
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Last modified: Saturday, 12 November 2011, 7:50 AM