3X HA tag - (Dec/03/2008 )
I am going to be tagging a potassium channel with HA at the N terminus. What are the pros and cons of a 1X HA tag vs 3X HA tag?
Depends on what you are going to be doing with the expressed protein although there really isn't much difference between 1 and 3 since the tag is so small but I've heard of people doing 12 or even 25 HA-tags! I work with HA-tag a lot and really like it. I only used one HA-tag which is preferable for imaging via immunofluorescence. If you have multiple tags, you can get an incredibly strong signal and will have difficulty determining any fine details such as localization but you will certainly be able to identify expressing cells. I prefer the one tag because the signal is very nice and easy to determine localization. However, if you are going to be doing interaction studies and will be wanting to do co-immunoprecipitations, the one HA-tag will most likely not be enough to get an efficient IP and then the three (or more) is preferable. Another thing to consider is the functionality of the protein. The smaller the tag the less chance of it interfering with the functionality of your protein, especially a channel protein. Here the one tag is preferable but you will most likely have no problems with three. All-in-all, I think you will be fine with the three and this gives you more flexibility for all sorts of different assays.