Related Experiment Video

Updated: Jun 3, 2026

Immunoprecipitation with an Anti-Epitope Tag Affinity Gel to Study Protein-Protein Interactions
07:16

Immunoprecipitation with an Anti-Epitope Tag Affinity Gel to Study Protein-Protein Interactions

Published on: January 5, 2024

Immunoprecipitation

K Johansen1, L Svensson

  • 1Department of Virology, Swedish Institute for Infectious Diseases Control, Stockholm, Sweden.

Methods in Molecular Medicine
|March 11, 2011
PubMed

Immunoprecipitation allows the investigator to detect and quantitate antigens in a mixture of proteins or characterize a specific antibody response to already well-characterized proteins. Addition of antibodies to proteins, usually radiolabeled, allows formation of antigen-antibody complexes. After separation from contaminating proteins, the complexes are disassociated and the proteins of interest are separated by sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE). Size and quantity of proteins may then be analyzed either by autoradiography or a gel scanning procedure. Immunoprecipitation is extremely sensitive and may detect very small amounts of radiolabeled protein (detection level ~100 pg protein or 100 cpm/protein). Unlabeled proteins may be used if other sensitive detection methods are utilized, e.g., enzymatic activity assays or Western blotting. The advantage of the immunoprecipitation technique vs immunoblotting is the possibility to analyze the immune response to proteins expressed in their native conformation. Radioimmunoprecipitation assay (RIPA) is used routinely for the detection of viral proteins, characterization of monoclonal and polyclonal antibody preparations, and determination of the specificity of the immune response to various pathogens (1-3).

More Related Videos

Co-immunoprecipitation of the Mouse Mx1 Protein with the Influenza A Virus Nucleoprotein09:39

Co-immunoprecipitation of the Mouse Mx1 Protein with the Influenza A Virus Nucleoprotein

Published on: April 21, 2015

Isolation of Cognate RNA-protein Complexes from Cells Using Oligonucleotide-directed Elution10:53

Isolation of Cognate RNA-protein Complexes from Cells Using Oligonucleotide-directed Elution

Published on: January 16, 2017

Related Concept Videos

Immunoprecipitation01:20

Immunoprecipitation

Immunoprecipitation, or IP, is a widely used technique that employs protein-antibody interactions to isolate proteins or protein complexes in their native state for studying protein-protein interactions, quaternary structures, or supramolecular complexes. Various modifications of the technique, including chromatin IP, cross-linking IP, and fluorescence IP, are commonly used.
Chromatin Immunoprecipitation
Chromatin immunoprecipitation, also known as ChIP, is used to study protein-DNA or...
Chromatin Immunoprecipitation- ChIP02:36

Chromatin Immunoprecipitation- ChIP

Chromatin immunoprecipitation, or ChIP, is an antibody-based technique used to identify sites on DNA that bind to transcription factors of interest or histone proteins. It also helps determine the type of histone modifications such as acetylation, phosphorylation, or methylation.
Types of ChIP
ChIP can be divided into two types - X-ChIP and N-ChIP. X-ChIP involves in vivo cross-linking of histones and regulatory proteins to DNA, fragmenting the DNA by sonication, and isolating the protein-DNA...
Precipitation and Co-precipitation01:17

Precipitation and Co-precipitation

Precipitation and coprecipitation methods can be used to separate a mixture of ions in a solution. In qualitative inorganic analysis, ions that form sparingly soluble precipitates with the same reagent are separated based on the differences in solubility products. For example, consider the separation of Cu(II) and Fe(II) ions by precipitation as insoluble sulfides. First, copper(II) sulfide is precipitated by the addition of acidic H2S, where the dissociation of H2S is suppressed. Adding H2S...
Immunogold Electron Microscopy01:20

Immunogold Electron Microscopy

Immunoelectron microscopy utilizes immunogold labeling of endogenous proteins with specific antibodies to detect and localize these proteins in cells and tissues. The procedure provides insights into the distribution and quantification of protein under different stimulation conditions offering clues about their functions. Conjugating highly electron-dense gold particles with primary or secondary antibodies allow antigen detection on and within cells, with high resolution and specificity.
Types of Coprecipitation01:10

Types of Coprecipitation

Coprecipitation is the contamination of a precipitate by otherwise soluble species and occurs via different processes. In colloidal precipitates, coprecipitation occurs via surface adsorption. For instance, barium sulfate has a primary layer of adsorbed barium ions and a secondary layer of nitrate counterions. This results in contamination of the precipitate by barium nitrate.
Sometimes, ions in a crystal lattice can undergo isomorphous replacement by inclusions of similar charge and size. For...