Electrophoretic Mobility Shift Assay (EMSA) Service


Electrophoretic mobility shift assay (EMSA), also known as gel retardation assay, is an important experimental method for studying the interaction of nucleic acids and proteins, and is the core technology for qualitative and quantitative analysis of interaction systems. This technology is often used to verify the interaction between transcription factors and promoters, and is now further developed to study DNA-protein interactions, RNA-protein interactions, and even DNA-RNA interactions.

EMSA is based on the principle that the mobility of nucleic acid-protein complexes is significantly reduced in native-PAGE, resulting in a lagged band in the final detection. In this experiment, specific and non-specific probes need to be designed so that they can bind to the target protein after incubation. As the molecular mass of the probe-protein complex increases, the immigration rates of the complex will reduce in SDS-PAGE compared with the probe that is not bound to the protein. Because there are some special markers in the probe (such as 32P), it can show bands by transmembrane, coloration or exposure to the probe-protein complex to prove the interaction between nucleic acid and protein. The experiment can also evaluate the binding affinity and even calculate the association and dissociation constant.

The schematic illustration of electrophoretic  mobility shift assays (EMSA)Figure 1. The schematic illustration of electrophoretic mobility shift assays (EMSA) (Song, C.C.; et al. 2015)


Creative Proteomics has accumulated nearly two decades of EMSA experience. Under the management of our professional technicians, a mature and high-quality EMSA platform has been established, which can help customers comprehensively and systematically analyze nucleotide-protein interactions. We provide a variety of radioactive isotopes and other labeling agents (such as biotin and FAM) to label nucleotides. Unlabeled nucleotides are used as specific competitors to eliminate non-specific nucleotide-protein interactions. In addition, our experts can customize experiments according to different project requirements, including but not limited to making changes in the following aspects:

  • Selection of nucleic acid target
  • Binding conditions
  • Additives
  • Competing nucleic acid
  • Electrophoresis conditions

Customers can choose different technology platforms according to project requirements, or contact us directly for consultation, and our expert team will provide you with customized experimental procedures.


  • Easy to operate
  • Wide range of applications
  • High sensitivity
  • Compatible with nucleic acids of various sizes and structures
  • Suitable for both highly-purified proteins and crude cell extracts

Creative Proteomics is an international biotechnology company dedicated to research in molecular interactions and other related fields. The electrophoretic mobility shift assay we provided has the characteristics of high quality and efficiency, and the data obtained can be directly used for paper publication. Our one-stop service aims to save customers time and money.   


  1. Hellman, L.M.; Fried, M.G. Electrophoretic Mobility Shift Assay (EMSA) for Detecting Protein-Nucleic Acid Interaction. Nat Protoc. 2007.
  2. Song, C.C.; et al. Choosing a suitable method for the identification of replication origins in microbial genomes. Front. Microbiol. 2015.
* This service is for RESEARCH USE ONLY, not intended for any clinical use.