Protein Interactions

We offer a number of products for the analysis of protein interactions, including pull-down assays, BRET-based and complementation reporter-based systems.

GST pull-down systems are used in traditional methods based on cell extracts and/or cell-free expression. The HaloTag® Mammalian Pull-Down System is used to isolate and identify intracellular protein complexes from mammalian cells.

NanoBRET™ and NanoBiT® technologies provide methods for direct analysis of protein interactions in live cells. The NanoBRET™ System uses bioluminescence resonance energy transfer (BRET) in a proximity-based assay that detects protein interactions by measuring energy transfer from a bioluminescent protein donor to a fluorescent protein acceptor.

NanoBiT® assays rely on a two-subunit system based on NanoLuc® luciferase that can be used for intracellular detection of protein:protein interactions. The subunits are fused to proteins of interest, forming a functional enzyme that generates a bright, luminescent signal when the proteins interact.

Pull-Down and Two-Hybrid Systems

Pull-down assays and two-hybrid systems are commonly used methods for studying protein interactions. We offer pulldown systems based on GST or HaloTag^® affinity tags, and a two-hybrid system designed for identifying mammalian protein interactions.

Protein:DNA Interactions

Promega products for studying protein:DNA interactions include gel shift assays and the HaloCHIP™ System—a fast alternative to traditional chromatin immunoprecipitation methods. In the HaloCHIP™ method, DNA-binding proteins of interest are expressed in cells as HaloTag® fusion proteins, crosslinked to DNA and then captured using the HaloLink™ Resin, which forms a highly specific, covalent interaction with HaloTag® proteins. The resin can be stringently washed to remove nonspecifically bound DNA and protein more efficiently than co-immunoprecipitation. The crosslinks are reversed to release purified DNA fragments from the resin. No antibodies are required.