Anna Bennett, Science Writer @ Promega
Bioluminescent assays are essential tools for tracking protein activity, cell signaling pathways and cellular dynamics. These assays provide high sensitivity, low background noise, and flexibility for live-cell applications—making them a fundamental tool in cellular biology. Traditionally, researchers have relied on luminometers to quantify signal output across multiwell plates. While bioluminescent assays paired with luminometers are powerful for measuring average activity across cell populations, they often miss spatial information and cell-to-cell variability that could be critical for interpreting biological responses
Bioluminescence imaging with the GloMax® Galaxy Bioluminescence Imager System (Promega) supports a range of applications—including protein:protein interactions and targeted protein degradation—offering a more detailed view of biology in real time. By enabling direct visualization of luminescent signals at the single-cell level, the system provides spatial and temporal resolution that traditional plate readers cannot discern.
One application area where bioluminescence imaging offers significant value is the study of protein:protein interactions. NanoLuc® Binary Technology (NanoBiT®) is a structural complementation reporter system using low affinity subunits of a luciferase that emit light upon reconstitution, a process triggered when two target proteins interact within the cellular environment. NanoBiT® assays provide a sensitive and dynamic method to detect molecular interactions in live cells. When paired with the GloMax® Galaxy Bioluminescence Imager, researchers gain the ability to visualize these interactions at the single-cell in real time.
This added resolution highlights spatial redistribution of a signal and differences in response across a population, providing a more complete picture of signaling events. For example, when HEK293 cells expressing NanoBiT®-tagged CX3CR1 and β-arrestin 2 were treated with the ligand Fractalkine, bioluminescent imaging revealed a shift in luminescent signal from the cell membrane to intracellular puncta over time. This spatial information provides direct evidence of receptor internalization that would be difficult to confirm using bulk luminescence alone. In this way, imaging serves as a valuable complement to plate reader assays, confirming and contextualizing population-level results.
Targeted protein degradation (TPD) is a second application where bioluminescence imaging adds critical value. In TPD assays, researchers aim to monitor the loss of specific proteins in response to degraders such as PROteolysis TArgeting Chimeras (PROTACs) or molecular glues. The HiBiT Protein Tagging System developed by Promega offers a highly sensitive method to detect these changes by tagging the protein of interest with a small luminescent peptide. While HiBiT assays provide robust, quantitative readouts of degradation kinetics in microplate-based formats, the GloMax® Galaxy Bioluminescence Imager facilitates direct observation of degradation events at the single-cell level. Researchers can assess how uniformly a degrader affects a population, observe the timing of signal loss in live cells and confirm whether the degradation occurs in specific subcellular compartments. This level of detail strengthens confidence in assay results and supports more informed decisions during degrader development and validation. Check out this article for more information about using the GloMax® Galaxy Imager for TPD.
At Promega, we designed the GloMax® Galaxy Bioluminescence Imager to bring greater clarity to foundational luminescent assays. By enabling spatial and temporal resolution at the single-cell level, the GloMax® Galaxy provides a deeper understanding of dynamic biological processes without adding complexity to your workflow. Whether you're interested in protein interactions or the effects of targeted degraders, the GloMax® Galaxy Bioluminescence Imager allows you to see your research in a new light. Learn more about the GloMax® Galaxy Bioluminescence Imager and how it can support your research here.
The GloMax® Galaxy Bioluminescence Imager is a research use only device.