Antibody Binding Affinities to Protein A and Protein G
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- Overview
- Protein A and protein G
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Overview
Depending on their host species and isotype, antibodies have different binding affinities to protein A and protein G. These properties are especially critical when deciding whether to use protein A or protein G coupled agarose, sepharose or magnetic beads in your immunoprecipitation experiments. While the binding affinity differences to protein A or protein G for a human IgG1 antibody may be minimal, for other antibodies the differences are severe; for example rat Ig2a does not bind to protein A but has a strong binding affinity to protein G.
In addition to immunoprecipitation experiments, the choice between protein A and protein G is also critical when selecting the best antibody purification method or kit.
Protein A |
Protein G |
|
|---|---|---|
|
Bovine IgG |
** |
**** |
|
Chicken IgY |
x |
* |
|
Goat IgG |
*/x |
** |
|
Guinea Pig IgG |
**** |
** |
|
Hamster IgG |
* |
** |
|
|
||
|
Human IgG1 |
**** |
**** |
|
Human IgG2 |
**** |
**** |
|
Human IgG3 |
x |
**** |
|
Human IgG4 |
**** |
**** |
|
Human IgA |
** |
x |
|
Human IgD |
** |
x |
|
Human IgE |
** |
x |
|
Human IgM |
** |
x |
|
|
||
|
Mouse IgG1 |
* |
** |
|
Mouse IgG2a |
**** |
**** |
|
Mouse IgG2b |
*** |
*** |
|
Mouse IgG3 |
** |
*** |
|
Mouse IgM |
*/x |
* |
|
Pig IgG |
*** |
*** |
|
Rabbit IgG |
**** |
*** |
|
Rat IgG1 |
x |
* |
|
Rat IgG2a |
x |
**** |
|
Rat IgG2b |
x |
** |
|
Rat IgG2c |
* |
** |
|
Rat IgM |
*/x |
x |
|
Sheep IgG |
*/x |
** |
Binding affinity ratings:
**** = Strong binding affinity
*** = Moderate binding affinity
** = Weak binding affinity
* = Very weak binding affinity
x = No binding affinity
Table and legend were adapted from here