What is the Difference Between Immunoprecipitation and Western Blot

The main difference between immunoprecipitation and western blot is that immunoprecipitation isolates a target protein from a solution using antibodies and agarose beads whereas western blot uses gel electrophoresis and antibody probes to analyze proteins.

Immunoprecipitation and western blot are two techniques of protein analysis. While immunoprecipitation uses radiolabeling, western blot uses antibodies for visualization of the separated proteins.

Key Areas Covered

1. What is Immunoprecipitation
   • Definition, Technique, Features
2. What is Western Blot
   • Definition, Technique, Features
3. Similarities Between Immunoprecipitation and Western Blot
   • Outline of Common Features
4. Difference Between Immunoprecipitation and Western Blot
   • Comparison with Key Differences

Key Terms

Immunoprecipitation, Protein Analysis, Western Blot

What is Immunoprecipitation

Immunoprecipitation is the technique of precipitating proteins out of the solution using antibody-specific binding to the target protein. Among thousands of proteins, it is important to both isolate and concentrate the proteins from a solution. Moreover, its antibodies are coupled to a solid substrate. However, the technique is important in individual protein immunoprecipitation, protein complex immunoprecipitation, chromatin immunoprecipitation, ribonucleoprotein immunoprecipitation, and tag proteins.

Figure 1: Chromatin Immunoprecipitation

Furthermore, the three methods of immunoprecipitation include direct, indirect, and selection. The direct immunoprecipitation method uses antibodies specific to the target protein to immobilize it on a solid surface. The indirect immunoprecipitation method uses antibodies specific to a group of proteins for immobilization. Moreover, the selection method is important when the concentration of the target protein is low in a solution.

What is Western Blot

Western blot or immunoblot is a technique of detecting proteins in a solution by size and specificity. This method uses three tasks to separate a protein: separation by size, transfer of protein to a solid support, as well as marking of target protein using a primary and secondary antibody to visualize.

Figure 2: Western Blot

First, the primary antibody binds to the target protein. Then, the secondary antibody binds to the primary antibody. Next is the binding of the secondary antibody. Finally, the detection is done by either staining, immunofluorescence, or radioactivity. However, proteins in the solution are fractionated by size by gel electrophoresis prior to the detection and specific binding of antibodies.

Similarities Between Immunoprecipitation and Western Blot

• Immunoprecipitation and western blot are two techniques of isolating proteins from solutions.
• Moreover, both use specific antibodies to target proteins in the process.

Difference Between Immunoprecipitation and Western Blot

Definition

Immunoprecipitation refers to the technique of precipitating a protein antigen out of solution using an antibody that specifically binds to that particular protein whereas western blot refers to a widely used analytical technique in molecular biology and immunogenetics to detect specific proteins in a sample of tissue homogenate or extract.

Importance

Usually, immunoprecipitation isolates a target protein from a solution using antibodies and agarose beads while western blot uses gel electrophoresis and antibody probes to analyze the size and the amount of proteins.

Conformation of Proteins

Immunoprecipitation works on the native conformation of a protein while western blot analyzes the denatured stage of a protein.

Concentration

Moreover, immunoprecipitation requires a higher concentration of proteins while western blotting is applicable for fewer concentrations of proteins in solutions.

Identification

However, immunoprecipitation uses radiolabeling while western blot uses antibodies conjugated with enzymes.

Conclusion

In brief, immunoprecipitation and western blot are two techniques of isolating proteins from a solution. In immunoprecipitation, the target protein is precipitated out from the solution, while in western blot, the proteins of the solution are fractionated by size. However, the detection method of both is mostly the same using antibodies. Hence, the main difference between immunoprecipitation and western blot is their function.

References:

1. Wikimedia Foundation. (2022, March 15). Immunoprecipitation. Wikipedia. Retrieved August 5, 2022.
2. Wikimedia Foundation. (2022, May 21). Western blot. Wikipedia. Retrieved August 5, 2022.

Image Courtesy:

1. ” Chromatin immunoprecipitation sequencing” By Jkwchui- Own Work (CC BY-SA 3.0) via Commons Wikimedia
2. ” Western Blot binding” Bensaccoun- Own Work (CC BY 3.0) via Commons Wikimedia