GST Pull-Down Protein Interaction Assay

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General Introduction of GST Pull-Down Protein Interaction Assay

Protein–protein interactions (PPIs) are fundamental to cellular function and disease research. Validating these interactions is essential for understanding biological mechanisms and identifying therapeutic targets.

Our GST Pull-Down Protein Interaction Assay provides a reliable, high-specificity method to confirm direct PPIs. Using GST-tagged bait proteins immobilized on glutathione beads, we capture interacting partners from purified proteins or complex lysates. Interactions are then analyzed by SDS-PAGE, Western blotting, or LC-MS/MS for accurate and reproducible results.

Whether validating known PPIs or discovering new binding partners, our flexible workflow delivers dependable data to support your research.

Highlights of Services

Customized Experimental Design

Each project is optimized based on protein characteristics and research goals.

Complete Workflow Support

From construct preparation to interaction analysis, we provide an integrated solution.

Multiple Detection Options

Choose from Western blot validation or high-resolution LC-MS/MS identification.

Experienced Protein Scientists

Our team supports challenging proteins, optimization, and troubleshooting.

Reliable Data Interpretation

Comprehensive reporting helps translate experimental results into biological insights.

Service Details

Section	Details
Sample & Input Requirements	Clients can provide one of the following: • Purified GST-tagged bait protein and purified prey protein(s) • Bait protein construct (plasmid/sequence) for in-house GST-tagged expression • Cell or tissue lysate to be screened against a bait protein
Optional Support	Don't have a GST-tagged construct yet? We also offer protein tagging and expression services to prepare your bait protein from scratch.
Deliverables	• Summary report of the pull-down analysis and interaction findings • Annotated gel and/or Western blot images • LC-MS/MS identification report (if applicable), including identified proteins and confidence scores.

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Workflow

Applications

Protein–Protein Interaction Validation

Protein Complex Characterization

Interaction Domain Mapping

Functional Mechanism Studies

Available Detection Platforms:

Detection Method	Application
Western Blot	Confirm known protein interaction
SDS-PAGE + Coomassie	Visualize pulled-down proteins
Silver staining	Detecting low abundance proteins
LC-MS/MS	Identify unknown interacting partners
Quantitative MS	Compare interaction changes

Case Study

Case 1: Identification of Novel Rab GTPase Effector Proteins Using GST Pull-Down Screening

Rab GTPases are key regulators of intracellular vesicle transport, and identifying their binding partners is critical for understanding their functions. In this study, researchers used a high-throughput GST pull-down assay with 60 GST-tagged Rab proteins to systematically screen interacting proteins from mammalian cell and tissue extracts.

The assay identified 21 Rab-interacting proteins, including several Rab GTPase-activating proteins (GAPs) with selective binding specificity. Among them, ACAP2 was identified as a Rab35-binding partner involved in regulating neurite development through Arf6 signaling.

This study demonstrates that GST pull-down assays provide a reliable platform for discovering novel protein interactions, validating binding specificity, and revealing new regulatory mechanisms.

(https://doi.org/10.1111/j.1600-0854.2010.01038.x）

(https://doi.org/10.1111/j.1600-0854.2010.01038.x)

FAQs

What is the difference between GST pull-down and Co-IP?

GST pull-down is an in vitro biochemical assay used to detect direct protein interactions, while Co-IP evaluates protein interactions within a cellular environment.

Can GST pull-down identify unknown interacting proteins?

Yes. GST pull-down combined with LC-MS/MS can identify unknown binding partners.

What controls are required?

GST-only control and input control are commonly used to distinguish specific interactions from non-specific binding.

Can mutant proteins be tested?

Yes. GST pull-down can be used for interaction domain mapping and mutation analysis.

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