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[Arabidopsis] cloning strategy for protein interaction using pETDuet-1 and Pull Down

Jose Pedro Fonseca via arab-gen%40net.bio.net (by zepedrof from gmail.com)
Fri Mar 20 13:11:24 EST 2009

Dear all,

I´m testing interaction of three proteins with a bait. Our plan is to
coexpress each one of the three target proteins separately with the
bait using pETDuet-1 (contains 2 multiple cloning sites (MCS), each
cloning site contains a tag (His tag and S tag) for protein isolation
and purification).

I´m trying to devise a best strategy for coexpression followed by pull
down assays and would appreciate if someone could suggest a good
strategy for this kind of experiment.

My question is: What is the best strategy to use?


1) Clone target protein A fused to a His tag into MCS1 and bait
protein fused to S tag into MCS2? Induce expression of both proteins
and separately purify protein A-his tag with a nickel resin and bait
with a S-affinity resin for pull down?

2) Clone target protein A fused to a His tag into MCS1  and bait
protein alone (no tag here) into MCS2 ? Induce expression of both
proteins and bind protein A into nickel resin.  But then how do I test
interaction of protein A with bait if the bait was not purified
previously with a different tag?
Can I use lysate of co-expressed proteins to bind bait to the protein
A previously bound to nickel resin?

Any help appreciated,


Graduate student

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