Co-IP vs Pull down - (Jun/28/2013 )

Hi,

I'm new to both Co-IP and GST-pull down. I was reading a paper where the author confirmed interaction between two proteins A and B uisng Co-IP. However he also did GST and his-tag pull down of both proteins? I thought doing one was sufficient? what is the difference between the two?

Many thanks

They are both pretty similar to each other, but in the case of GST/His the pulldown is usually achieved using GSH (for GST) or nickel ion (for His tag) based methods rather than antibody based.

They will have used both as a confirmatory approach for the interaction, similar to using both co-IP and confocal to demonstrate that proteins interact.

I personally think Co-IP is much better than pull-Down. Most reserachers will do both or even more assay to check if two proteins can interact with each other.