Pull-Down Assay


Pull-down assay is a in vitro method used  to concentrate the target protein or direct protein-protein interaction. It is  often used by biochemists to verified the protein-protein interaction predicted  by other assay. It utilize beads conjugated with bait protein, which is predicted  to interact with the target protein, to trap the prey, followed by downstream  analysis of bait-prey complex, for instance, Western blotting and mass  spectrometry.

The principle of pull-down assay is  affinity purification, which is similar to immunoprecipitation, except that  this method uses bait protein, instead of antibody to trap the target protein. In  a pull-down assay, a bait protein is tagged and immobilized on beads with  affinity ligand specific for the tag, thereby generating a "secondary affinity  support" for purifying other proteins that interact with the bait  protein. When incubated with a protein sample that contains putative  "prey" proteins, such as a cell lysate, the bait can bind the prey,  and thus trap down the prey from the lysate.

In addition to investigating the  interaction of two proteins, pull-down assays can also be used to detect the  activation status of specific proteins. Activation of proteins are often couple  with protein conformational change, and the bait selectively binds to a  specific conformation. In this case, pull-down assay can be utilized to  selectively purify the active prey. For instance, GTPase effectors only recognize  the active GTPases, thus when using GTPase effectors as the bait, only the  active GTPases are trapped and purified, and the proportion of active GTPase  can thus be measured.

Pull-Down Assay

Type  of tag of the bait

There are many types of tags for the bait  of pull-down assay, such as GST, poly-His, and biotin, etc. The affinity ligand  used to immobilize bait are glutathione, nickel and chelate complexes, and  streptavidin, respectively.

Bait tagAffinity ligand
Glutathione S-transferase (GST)Glutathione
Poly-histidineNickel or cobalt chelate complexes

Creative Proteomics provides the above  pull-down assays to suits the specific needs of your project. Our buffers and  analytical systems are optimized and can be also adjusted based your project  needs as well. You welcome to send us inquiry to discuss the specific needs of your project.

Features  of Pull-Down Assay

Our Pull-Down  Assay service contains:

Ordering Procedure:

Ordering Procedure

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