Question (11999) | Anti-Cannabinoid Receptor I antibody (ab3558)

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Question

I haved received the replacement of CB1 antibody. I tested it and found two bands in my membrane from rat brains, one is about 80 kD, the other is about 45kD. The specific band should be ~60kD. I do not know what happened.

Answer

Thank you for your email. I recall that you were previously unable to obtain any bands with this antibody. I would like to investigate this present issue further but do need details regarding your protocol in order to do that. If you could answer the questions below, it would be very helpful. 1. Please describe the problem (high background, wrong band size, more bands, no band etc). 2. On what material are you testing the antibody in WB? •Species? •Cell extract/ Nuclear extract? •Purified protein? •Recombinant protein? 3. How much protein did you load? •How did you prepare the lysate for the analysis (protease inhibitors etc)? •Did you heat the samples? 4. Primary Antibody •Specification (in which species was it raised against)? •At what dilution(s) have you tested this antibody? •Incubation time, wash step? 5. Secondary Antibody •Specification (in which species was it raised against)? •At what dilution(s) have you tested this antibody? •Incubation time, wash step? •Do you know whether the problems you are experiencing come from the secondary? 6. What detection method are you using? 7. Background bands •Have you eliminated the possibility that any background bands could be due to the secondary antibody? (Run a “No primary” control) •Is the blocking step sufficient? (We recommend blocking the membrane by adding 20 ml of blocking buffer (5% non-fat dry milk, 0.1% Tween-20 in TBS). Incubate for 2 h at room temperature or overnight at 4°C with agitation) •Are your washing steps sufficiently stringent? (Multiple short washes are more effective than fewer longer wash steps) •At what size are the bands migrating? Could they be degradation products of your target? •Please provide an image of your blot (as an e-mail attachment, a faxed image is not sufficient) 8. Optimization attempts •How many times have you tried the Western? •Do you obtain the same results every time e.g. are background bands always in the same place? •What steps have you altered? 9. Did you apply positive and negative controls along with the samples? Please specify.

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