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A. Preparation of cell lysates
- Collect cells (confluent T-25) by trypsinization and spin.
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Lyse the pellet with 100 µl lysis buffer on ice for 10 min.
For 500,000 cells, lyse with 20 µl. - Spin at 14,000 rpm (16,000 g) in an Eppendorf microfuge for 10 min at 4°C.
- Transfer the supernatant to a new tube and discard the pellet.
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Determine the protein concentration (Bradford assay, A280, or BCA)
(We use the Bradford assay from Bio-Rad.) - Take x µl (= y µg protein) and mix with x µl of 2x sample buffer.
- Boil for 5 min.
- Cool at RT for 5 min.
- Flash spin to bring down condensation prior to loading gel.
B. Polyacrylamide gel (14.5 cm x 16.5 cm)
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Agarose plug:
1% agarose dissolved in 1x Resolving gel buffer.
(I make 50 ml, keep melting it as I need it, and re-adding water to maintain agarose conc.) -
Resolving gel: 24 ml of a 9% gel
5.4 ml 40% acrylamide/bisacrylamide (29:1 mix)
3 ml 8x Resolving gel buffer
15.6 ml water
12 µl TEMED
60 µl 20% ammonium persulfate -
Stacking gel: 8 ml
1 ml 40% acrylamide/bisacrylamide (29:1 mix)
2 ml 4x Stacking gel buffer
5 ml water
8 µl TEMED
21.6 µl 20% ammonium persulfate
C. Preparation of gel
- Assemble the glass plates and spacers (1.5 mm thick).
- Pour an agarose plug (1-2 mm).
- Pour the running gel to about 1 cm below the wells of the comb (~20 ml).
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Seal with 1 ml water-saturated 1-butanol.
(Can stop here and leave gel as is overnight if you want.) - When gel has set, pour off the butanol and rinse with deionized water.
- Pour the stacking gel (~5 ml) and insert the comb immediately.
- When the stacking gel has set, place in gel rig and immerse in buffer.
- Prior to running the gel, flush the wells out thoroughly with running buffer.