Protein Interaction - CD BioSciences


Protein Interaction

Protein Interaction

The interactions of proteins with other molecules (e.g. proteins, DNAs, hormones, lipids) fundamentally underlie the function of a living system. By physically contact with other molecules through hydrogen or hydrophobic bonds, Van der Waals forces, ionic forces, or even covalent bonds, protein molecules function as regulators, receptors, or transporters to carry out works supporting cellular activities such as signaling transduction, molecular transportation, and metabolic regulation. 

In a signaling pathway, proteins constantly interact with other proteins, which is the basis of the regulation. Disruption of these interactions causes malfunction of signaling transduction and may eventually lead to relevant diseases.

Studying protein interactions is central in the area of bioscience and medical research. With extensive experience, CD BioSciences offers a variety of assays to help you identify and manipulate protein interactions.

Protein Interaction

Our Services

Protein-protein and protein-ligand interactions are the core of almost every cellular process and drug discovery project. The study of protein interactions provides insight into biological processes mediated or affected by proteins. CD BioSciences offers a portfolio of customizable services to allow for accurate and sensitive detection of protein interactions in vivo or in vitro.

Please note that our protein interaction services are not limited to protein-protein interaction (PPI), protein-DNA interaction (PDI or DPI), and protein-RNA interaction (PRI or RPI), but include interactions between proteins, peptides, DNA, RNA, aptamers, small molecules, molecular fragments, ions, lipids, virus-like-particles, and artificial particles.

Methods Protein Interactions
In Vivo Fluorescence Resonance Energy Transfer (FRET) & Bioluminescence Resonance Energy Transfer (BRET) PPI
Yeast Two-hybrid (Y2H) PPI; PDI; PRI
Membrane-based Yeast Two-hybrid (MbY2H) PPI; PDI
Immunoprecipitation (IP) PPI; PDI; PRI
In Vitro Microscale Thermophoresis (MST) PPI; PDI; PRI and Others
Isothermal Titration Calorimetry (ITC) PPI; PDI; PRI and Others
Surface Plasmon Resonance (SPR) PPI; PDI; PRI and Others
Bio-layer Interferometry (BLI) PPI; PDI; PRI and Others
Pull-down Assay PPI; PDI; PRI and Others

In Vivo

  • Fluorescence Resonance Energy Transfer (FRET) detects energy transfer between two light-sensitive molecules (chromophores). FRET is measured by determining if two fluorophores (one common pair is CFP and YFP) are within a certain distance of each other. It can be used to measure the distances between domains in a single protein, detect interactions between proteins and study other interactions.

    To avoid FRET's requirement for external illumination to initiate the fluorescence transfer, Bioluminescence Resonance Energy Transfer (BRET) uses a bioluminescent luciferase (typically the luciferase from Renilla reniformis) rather than CFP to produce an initial photon emission compatible with YFP.

    Applications: Protein-protein Interaction.

  • Yeast Two-hybrid (Y2H)
  • The yeast two-hybrid (Y2H) system is the most popular method to identify binary PPIs in vivo, which is based on the reconstitution of a functional transcription factor (i.e. GAL4) when two proteins interact physically. It has been successfully applied to screen potential interactions in multiple organisms since developed in a high-throughput format.

    Alternated versions of Y2H have been developed to broaden its applications. Yeast One-hybrid (Y1H) is designed to investigate protein-DNA interactions. And protein-RNA interactions can be investigated using Yeast Three-hybrid (Y3H).

    Applications: Protein-protein Interaction; Protein-DNA Interaction; Protein-RNA Interaction.

  • Membrane-based Yeast Two-hybrid (MbY2H)
  • Some proteins (e.g. integral membrane proteins or transcription regulators) are relatively difficult to investigate using standard yeast two-hybrid methods, because they either are located in cell membranes or activate the system without real protein interactions.

    To avoid the drawback of Y2H as it is limited to study cytosolic or extracellular soluble proteins, MbY2H, also called split ubiquitin Y2H, which is based on the split-ubiquitin ubiquitin protein complementation assay has been developed to detect protein interactions directly at the membrane. Like Y2H, the MbY2H system can also be used to screen complex DNA libraries in a high-throughput format.

    Applications: Protein-protein Interaction; Protein-DNA Interaction.

  • Immunoprecipitation (IP)
  • Immunoprecipitation (IP) is a method to isolate a specific protein out of a solution using a corresponding antibody to detect the physical interaction of the target protein with other proteins or nucleic acids. To achieve different interaction analyses, different versions of IP have been developed, i.e., Co-IP, ChIP, RIP.

    Co-immunoprecipitation (Co-IP) is used for the detection of PPIs using an antibody targeting a known protein to immunoprecipitate intact protein complexes containing antigen and any other proteins bound to it.

    Chromatin immunoprecipitation (ChIP) is a method to detect protein-DNA interactions. It is used to determine the DNA binding sites of a protein (e.g. a transcription factor).

    RNP immunoprecipitation (RIP) is similar to ChIP, where RNAs associated with targets proteins are isolated and further analyzed.

    Applications: Protein-protein Interaction; Protein-DNA Interaction; Protein-RNA Interaction.

In Vitro

  • Microscale Thermophoresis (MST)
  • MST is a biophysical method for quantifying the affinity of biomolecular interactions, which measures the motion of molecules with fluorescence along microscopic temperature gradients that changes upon ligand binding.

    MST works with target molecules with extrinsic or intrinsic fluorescence and any non-fluorescent ligands. As an immobilization-free technology, it requires a low amount of analyte samples. It delivers dissociation constant KD (binding affinity) of your protein to its natural ligand or to other possible targets, including DNAs, RNAs, ions, small molecules.

    Applications: Protein-protein Interaction; Protein-DNA Interaction; Protein-RNA Interaction; Protein-small molecule Interaction and Others.

  • Isothermal Titration Calorimetry (ITC)
  • ITC is a gold standard biophysical method for determining the thermodynamic parameters of molecular interactions in solution. This label free technique directly measures the heat released or absorbed during a biomolecular binding event. It is commonly used to determine the binding of small molecules such as medical compounds to large macromolecules such as proteins.

    ITC is the only technique that can simultaneously determine all binding parameters (binding affinity/ Ka, reaction stoichiometry/ n, enthalpy/ ∆H and entropy/ ΔS) in a single experiment. 

    Applications: Protein-protein Interaction; Protein-DNA Interaction; Protein-RNA Interaction; Protein-small molecule Interaction and Others.

  • Surface Plasmon Resonance (SPR)
  • SPR is a highly accurate and sensitive kinetics and affinity measuring technology, which is commonly used to analyze biomolecular interactions. The measurement of SPR requires no labeling for the detection of analytes and can be followed in real-time.

    Employing the cutting-edge BIAcore system, we are capable of offer SPR services of any kind, so you can determine the interaction between proteins, peptides, oligonucleotides, and small molecular compounds.

    Applications: Protein-protein Interaction; Protein-DNA Interaction; Protein-RNA Interaction; Protein-small molecule Interaction and Others.

  • Bio-layer Interferometry (BLI)
  • BLI is label-free technology commonly used for quantitative and qualitative characterization of biomolecular interactions, which is based on the principle of optical interferometry. It can analyze the interference pattern of white light reflected from two interfaces: an internal reference layer and an external layer of immobilized protein on the biosensor tip. Changes in the number of molecules bound to the biosensor tip cause a shift in the interference pattern, which can be recorded in real-time with high accuracy. BLI works with many classes of target molecules that can be coupled to a sensor surface.

    Applications: Protein-protein Interaction; Protein-DNA Interaction; Protein-RNA Interaction; Protein-small molecule Interaction and Others.

  • Pull-down Assay
  • Protein pull-down assay is a commonly used in vitro approach to study PPIs, which is similar to immunoprecipitation. In an immunoprecipitation assay, antibodies are used to drag protein complexes out of a solution, while in a pull-down assay, bait proteins are tagged and immobilized on beads to be used to trap target proteins. It can be used for confirmation of existing PPIs or screening to identify novel PPIs. Using other biomolecules (e.g. small-molecule chemicals, nucleotides) as bait, it can also be adapted to study other interactions.

    Applications: Protein-protein Interaction; Protein-DNA Interaction; Protein-RNA Interaction; Protein-small molecule Interaction and Others.


CD BioSciences offers cost-effect, high quality and hassle-free protein interaction services to our clients worldwide. We guarantee to deliver our results on time. Please feel free to contact us.

For research use only. Not intended for any clinical use.