What is difference among Protein A, protein G, and Protein A/G? - (Jun/07/2007 )

new to chip assay, so lots stupid question I guess. . these are three kind of agarose resin used in CHIP assay to bind to antibody. so what is difference among them? Which condition use which? any preferred in certain situation?

Thanks guys. I found here is really helpful.

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The difference is in the specificity for different antibody types and subtypes. Protein A is more broad in it's ability to bind human antibody types other than IgG but it specifically does not bind IgG3 very well. Protein G binds all human IgG subtypes well. Protein G also is more versitile when it comes to binding of IgG subtypes of other species. A resin with both types (protein A/G resin) should be most inclusive in terms of the antibody types it binds. Having said that, we haven't had any problems in ChIP assays using protein A beads alone.

Hope that helps.

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