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Protein A vs. Protein G: What's the Difference?

Edited by Huma Saeed || By Sawaira Riaz || Published on January 29, 2024
Protein A binds to the Fc region of antibodies, especially IgG; Protein G also binds to the Fc region but has a broader range of antibody isotypes it can bind to.

Key Differences

Protein A, primarily found in the cell wall of Staphylococcus aureus, has a strong affinity for the Fc region of antibodies, particularly IgG. In contrast, Protein G, derived from Group C and G Streptococci, also binds to the Fc region of antibodies but exhibits a wider binding range, including IgA and IgM, in addition to IgG.
Huma Saeed
Jan 29, 2024
The binding specificity of Protein A is primarily towards human IgG1, IgG2, and IgG4. Protein G, on the other hand, shows a broader specificity, effectively binding to all human IgG subclasses and offering higher affinity for certain types of IgG than Protein A.
Sawaira Riaz
Jan 29, 2024
In biotechnological applications, Protein A is often used for antibody purification due to its specific interaction with IgG. Protein G, given its broader specificity, is favored in assays requiring binding to a variety of antibody isotypes or in cases where Protein A's affinity is inadequate.
Sawaira Riaz
Jan 29, 2024
The stability and binding conditions of Protein A and Protein G also differ. Protein A is less stable at low pH, which can be a limitation in some protocols. Protein G, in contrast, maintains stability and binding capacity across a broader range of pH levels, making it more versatile.
Aimie Carlson
Jan 29, 2024
Both proteins are vital tools in immunology and biochemistry, Protein A's narrower specificity can be advantageous for targeted IgG isolation. Protein G's wider range of antibody interaction makes it a more flexible tool for capturing a diverse array of antibody isotypes.
Sawaira Riaz
Jan 29, 2024
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Comparison Chart

Source

Staphylococcus aureus
Group C and G Streptococci
Sawaira Riaz
Jan 29, 2024

Antibody Binding Affinity

High for IgG1, IgG2, IgG4
High for all IgG subclasses, IgA, and IgM
Huma Saeed
Jan 29, 2024

Binding Specificity

More specific to certain IgG subclasses
Broader specificity to various antibody types
Sawaira Riaz
Jan 29, 2024

Stability

Less stable at low pH
Stable across a wider pH range
Aimie Carlson
Jan 29, 2024

Biotechnological Application

Preferred for specific IgG isolation
Used for broader antibody isotype purification
Sawaira Riaz
Jan 29, 2024
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Protein A and Protein G Definitions

Protein A

A cell wall component of certain bacteria, known for its antibody-binding properties.
Researchers use Protein A to detect specific antibodies in serum samples.
Sawaira Riaz
Dec 19, 2023

Protein G

A bacterial protein from Group C and G Streptococci, known for binding to various antibody isotypes.
Protein G's versatility is crucial in purifying diverse antibodies from serum.
Sawaira Riaz
Dec 19, 2023

Protein A

A protein leveraged for its strong affinity to human IgG subclasses in biochemical applications.
Protein A is integral in ELISA assays for capturing target IgG antibodies.
Sawaira Riaz
Dec 19, 2023

Protein G

A widely used tool in immunology for its ability to bind to all subclasses of human IgG.
In western blotting, Protein G is preferred for detecting multiple IgG subclasses.
Sawaira Riaz
Dec 19, 2023

Protein A

A protein from Staphylococcus aureus that binds specifically to the Fc region of IgG antibodies.
Protein A is used in immunoprecipitation to isolate IgG-bound antigens.
Sawaira Riaz
Dec 19, 2023

Protein G

A Streptococcal protein employed in antibody purification and detection due to its broad specificity.
Protein G coated beads are effective in immunoprecipitation assays.
Harlon Moss
Dec 19, 2023

Protein A

A biotechnologically important protein for selective immunoglobulin purification.
Affinity chromatography using Protein A efficiently purifies IgG from complex mixtures.
Aimie Carlson
Dec 19, 2023

Protein G

A protein with a broad affinity for the Fc region of antibodies, including IgG, IgA, and IgM.
Protein G is used in immunoassays to capture a wide range of antibody types.
Huma Saeed
Dec 19, 2023

Protein A

A bacterial protein utilized in antibody purification and immunological assays.
Protein A columns facilitate the purification of monoclonal antibodies.
Sawaira Riaz
Dec 19, 2023

Protein G

A stable and versatile protein used in biotechnological applications for antibody interaction.
Due to its pH stability, Protein G is ideal for antibody purification under various conditions.
Aimie Carlson
Dec 19, 2023

FAQs

What's the main use of Protein A?

Primarily used for specific IgG antibody purification.
Sawaira Riaz
Jan 29, 2024

How does Protein A bind to antibodies?

It binds to the Fc region of IgG antibodies.
Sawaira Riaz
Jan 29, 2024

What's the main use of Protein G?

Used for purifying a broad range of antibody types, including all IgG subclasses.
Sawaira Riaz
Jan 29, 2024

What is Protein G?

A protein from Group C and G Streptococci, with a broad affinity for various antibody isotypes.
Huma Saeed
Jan 29, 2024

Where is Protein G found naturally?

In Group C and G Streptococci.
Sawaira Riaz
Jan 29, 2024

How does Protein G bind to antibodies?

It has a broad binding range, including the Fc regions of IgG, IgA, and IgM.
Harlon Moss
Jan 29, 2024

Where is Protein A found naturally?

In the cell wall of Staphylococcus aureus.
Sawaira Riaz
Jan 29, 2024

Is Protein A stable at low pH?

It is less stable at low pH.
Sawaira Riaz
Jan 29, 2024

What is Protein A?

A bacterial protein from Staphylococcus aureus, binding to the Fc region of IgG antibodies.
Sawaira Riaz
Jan 29, 2024

Can Protein G bind to all IgG subclasses?

Yes, it binds to all human IgG subclasses.
Harlon Moss
Jan 29, 2024

What makes Protein G versatile in antibody binding?

Its broad specificity to various antibody types.
Sawaira Riaz
Jan 29, 2024

Is Protein G used in clinical diagnostics?

Yes, especially in assays requiring broad antibody detection.
Janet White
Jan 29, 2024

How is Protein A important in biotechnology?

It's crucial for specific antibody purification and detection.
Janet White
Jan 29, 2024

Can Protein A bind to all IgG subclasses?

It binds strongly to IgG1, IgG2, and IgG4.
Sawaira Riaz
Jan 29, 2024

Is Protein G stable at low pH?

It maintains stability across a wider pH range.
Harlon Moss
Jan 29, 2024

What is a common application of Protein A in research?

It's used in immunoprecipitation and ELISA assays.
Aimie Carlson
Jan 29, 2024

What is a common application of Protein G in research?

It's used in a variety of immunoassays and antibody purification methods.
Sawaira Riaz
Jan 29, 2024

Is Protein A used in clinical diagnostics?

Yes, particularly in assays for specific IgG detection.
Harlon Moss
Jan 29, 2024

What makes Protein A specific in antibody binding?

Its specificity to certain IgG subclasses.
Sawaira Riaz
Jan 29, 2024

How is Protein G important in biotechnology?

It's versatile for purifying and detecting a wide range of antibodies.
Sawaira Riaz
Jan 29, 2024
About Author
Written by
Sawaira Riaz
Sawaira is a dedicated content editor at difference.wiki, where she meticulously refines articles to ensure clarity and accuracy. With a keen eye for detail, she upholds the site's commitment to delivering insightful and precise content.
Edited by
Huma Saeed
Huma is a renowned researcher acclaimed for her innovative work in Difference Wiki. Her dedication has led to key breakthroughs, establishing her prominence in academia. Her contributions continually inspire and guide her field.

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