Why should I use an IgG control in my IP experiment?

Isotype control antibodies are used to estimate the nonspecific binding of target primary antibodies due to Fc receptor binding or other protein-protein interactions. IgG controls lack the specific binding region of the antibody, however it matches the class of your primary antibody.

When we run IPs, we typically run 2 different negative controls:

1. A bead only control: Beads are incubated with the lysate but no antibody is added.
   1. If signal is observed with this control, it indicates that your target protein of interest is non-specifically binding to the beads.
2. IgG control: Lysate is incubated with the appropriate IgG control antibody instead of your target antibody. This mixture in then incubated with the beads to complete the experiment.
   1. If you see pull down, it indicates that your target of interest is non-specifically binding to the IgG portion of the antibody.
   2. When using an IgG control, you will need to match the concentration to the concentration of primary antibody that you are using for pull-down for an accurate comparison.

We recommend the IgG controls below based on your chosen target antibody:

• For rabbit monoclonal antibodies use Rabbit (DA1E) mAb IgG XP® Isotype Control #3900. 
• For rabbit polyclonal antibodies use Normal Rabbit IgG #2729. 
• For mouse IgG1 antibodies use Mouse (G3A1) Monoclonal Antibody IgG1 Isotype Control #5415.
• For mouse IgG2a antibodies use Mouse (E5Y6Q) Monoclonal Antibody IgG2a Isotype Control #61656.
• For mouse IgG2b antibodies use Mouse (E7Q5L) Monoclonal Antibody IgG2b Isotype Control #53484.
• For mouse IgG3 antibodies use Mouse (E1D5H) Monoclonal Antibody IgG3 Isotype Control #37988.

Last updated: June 30, 2026