The EMSA Assay in Plants

The EMSA Assay in Plants Inquiry

The Electrophoretic Mobility Shift Assay (EMSA) is a core technology used to detect the interactions between protein (complexes) and nucleic acids (1). This assay is widely applicable to various bio-sample analyses, and is capable of delivering both qualitative and quantitative characterizations of nucleic acid-protein interactions (2). Lifeasible provides services for sensitive, rapid EMSA assays that can examine interactions among a wide range of plant proteins and nucleic acids.

The principle of the EMSA assay is based on the electrophoretic mobility changes upon nucleic acid-protein interactions. Specifically, during gel electrophoresis, the motilities of protein-DNA or protein-RNA mixture vary depending on their size, electric charge and/or stoichiometry structure. Compared to the unbound DNA or RNA fragments, those that bind with a protein or protein complex would move more slowly, represented by a separated band indicating a larger size on the gel (Figure 1) (3). Further, the nucleic acids can be detected via radioisotope labeling, fluorescence labeling, chemiluminescence or immunohistochmical detection methods.

EMSA.png Figure 1. A schematic representative of the classic EMSA.

Compared to other protein-nucleic acid interaction assays, the EMSA holds the following advantages:

  • High sensitivity
  • Feasible for both purified proteins and crude cell/tissue extracts
  • Wide ranges of conditions that can be applied for a variety of proteins and nucleic acids
  • Quick and simple to perform

Aside from the classical EMSA, Lifeasible also offer a number of alternatives, such as nitrocellulose filter-binding and footprinting (4, 5), that are optimized to allow quantitative detections of binding kinetics as well as equilibrium measurements. Here at Lifeasible, our team of skilled scientists and experts has years of experience in both classical EMSA and other alternative EMSA assays. Our quality-ensured and technically flexible services make sure that your needs for each project can be met.


  1. Garner MM & Revzin A (1981) A gel electrophoresis method for quantifying the binding of proteins to specific DNA regions: application to components of the Escherichia coli lactose operon regulatory system. Nucleic Acids Res 9(13):3047-3060.
  2. Hellman LM & Fried MG (2007) Electrophoretic mobility shift assay (EMSA) for detecting protein-nucleic acid interactions. Nat Protoc 2(8):1849-1861.
  3. Fried M & Crothers DM (1981) Equilibria and kinetics of lac repressor-operator interactions by polyacrylamide gel electrophoresis. Nucleic Acids Res 9(23):6505-6525.
  4. Hall KB & Kranz JK (1999) Nitrocellulose filter binding for determination of dissociation constants. Methods Mol Biol 118:105-114.
  5. Brenowitz M, Senear DF, Shea MA, & Ackers GK (1986) Quantitative DNase footprint titration: a method for studying protein-DNA interactions. Methods Enzymol 130:132-181.
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