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Western Blotting
Sample preparation
1. Aspirate media from cultures and Wash the cells with 1X PBS.
2. Lyse cells by adding 1X SDS sample buffer and transfer the extract to a microcentrifuge tube. Keep onice.
3. Sonicate for 10–15 sec to complete cell lysis and shear DNA.
4. Heat a 20 μl sample to 95–100°C for 5 min, then cool on ice.
5. Centrifuge for 5 min (with Microcentrifuge).
6. Load appropriate volumes of samples onto SDS-PAGE gel (loading quantity of protein sample depends on the concentration of extracted proteins).
NOTE: At the same time, please load the pre-stained molecular weight markers to determine molecular weights and verify electrotransfer.
7. Electrotransfer to nitrocellulose/PVDF membrane.
Membrane Blocking and Antibody Incubations
a. Blocking
1. (Optional) After transfer, wash the transferred membrane with TBS for 5 min at room temperature.
2. Incubate the membrane in the blocking buffer for 1 hr at room temperature.
3. Wash three times for 5 min each with TBST.
b. Antibodies Incubation
1. Incubate membrane and primary antibody (at the appropriate dilution and diluent recommended) in a primary antibody dilution buffer with gentle agitation overnight at 4°C.
2. Wash three times for 5 min each with TBST.
3. Incubate membrane with an appropriate second antibodydissolved in the blocking buffer with gentle agitation for 1 hr at room temperature.
4. Wash three times for 5 min each with TBST.
5. Proceed with detection.
Detection of Proteins
1. After antibodies incubation, Wash membrane three times for 5 minutes in TBST.
2. PrepareECL Reagent (or other chromogenic agents/substrate according to your second antibody). Mix well.
3. Incubate substrate with membrane for 1 minute, remove excess solution (membrane remains wet), wrap in plastic and expose to X-ray film.
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