Phospho-Histone H2A.X (Ser139) Monoclonal Antibody (CR55T33), Alexa Fluor™ 488, eBioscience™ - FAQs

Antibodies are tested and validated in a variety of ways. First, we verify that in a panel of cells in which different pathways have been induced, we see phosphorylation specific staining only in the cells in which the specific pathway of interest has been activated. Second, we verify that phosphorylation specific staining is observed only in cell types in which the protein is expressed and not in cell types in which the protein is not expressed. Third, whenever possible, western immunoblotting is used to confirm the presence of a band(s) of the appropriate size(s) in stimulated/treated cells (and not in unstimulated/untreated cells, as appropriate).

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We have data demonstrating that fixed cells stored in methanol are stable at -20 degrees C or at -80 degrees C for several weeks. We do not recommend storing fixed cells in eBioscience Foxp3/Transcription Factor Buffer. However, cells fixed with eBioscience Foxp3/Transcription Factor Buffer or eBioscience Intracellular (IC) fixation buffer can be stored in eBioscience IC fixation buffer for up to 3 days at 4 degrees C in the dark.
Note: Please be aware that higher compensation values may be seen with tandem dyes if any other fixative is used apart from eBioscience IC fixation buffer, for 3-day storage.

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Each antibody has been tested in three different buffer systems: IC fixation and permeabilization, Foxp3/Transcription Factor Buffer, and IC fixation Buffer/Methanol. The recommended buffer system(s) will be noted on the Technical Data Sheet for the specific antibody.

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Because methanol can destroy the epitope recognized by some antibodies, ideally surface staining would be performed at the beginning of the protocol with a methanol-resistant fluorochrome (like eFluor 450, FITC, and eFluor 660).
Please recognize that surface staining before stimulation can have undesired effects due to activation of the cell caused by antibody binding. We recommend staining after stimulation/treatment, fixation, and methanol treatment.

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In general, you can use other companies' buffer systems provided that their buffers are of a similar composition as the buffers recommended. Be aware that results will vary depending upon the buffer system used. eBioscience antibodies have been optimized for use in eBioscience buffers and we have not tested all of our antibodies in other buffer systems. Thus, we highly recommend using our optimized protocol and buffer systems.

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It is important to understand whether the stimulation/treatment results in an upregulation or a down regulation of the phosphorylation event. Thus, it is recommended that changes in phosphorylation levels in stimulated/treated versus unstimulated/untreated cells be compared. A histogram or density plot overlay these two treatments will provide a better assessment of a change in phosphorylation event than using isotype controls.

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In theory, if the buffer systems are compatible for the antibodies of interest, this can be done. In practice, cytokine translation and phosphorylation events do not typically occur in the same timeframe, therefore, it may be difficult to detect both events in the same sample. The results will be depended on the kinetics and should be determined for each system and protein of interest.

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In theory, this can be done if the antibodies against both the transcription factor and the phosphorylated protein work in the same buffer system. For example, Anti-Human/Mouse phsopho-H2AX and all transcription factor eBioscience antibodies offered will work in the Foxp3/Transcription Factor Buffer System (Cat. No. 00-5523-00).

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In theory, this can be done if the antibodies to both proteins work in the same buffer system and if the antibodies recognize different epitopes. Please refer to the individual Technical Data Sheets for information about buffer compatibility. Also, consider using eBioscience InstantOne ELISA Kits for immunoassay quantitation of both total and phosphorylated proteins such as AKT1/2/3, JNK1/2/3, NFκB, STAT3, and STAT5.

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