Live-Cell Target Engagement

Portal & AbbVie: Unlocking Intracellular Insights for Drug Discovery

See how Portal and Promega are enabling AbbVie to test impermeable small molecules, protein degraders, and gene editing constructs inside living cells to accelerate early drug discovery decisions.

Upgrade your research with ready-to-run workflow kits:

Proof Points

Dose-Dependent Tracer Displacement in Live Cells

We boosted a membrane-impermeable Src kinase tracer into HeLa cells expressing NanoLuc-Src, then challenged it with ponatinib or bosutinib. Boosted cells gave about 20× the BRET signal of unboosted cells. Ponatinib displaced the tracer dose-dependently, cutting the signal about 35% at 1.1 µM, about 55% at 3.3 µM, and about 80% at 10 µM; bosutinib reached about 85% at 10 µM. Unboosted cells stayed at baseline across the whole curve.

Partially Permeable Degraders Ubiquitinate More Once Delivered

Cellular ubiquitination of the target protein in a degrader mechanism-of-action panel run by a pharma partner, showing normalized POI:ubiquitin BRET response. Both partially permeable compounds increased ubiquitination about 2.3-fold after delivery, while DMSO showed no significant difference and the permeable control was unchanged. Ternary complex formation and proteasome recruitment increased to the same extent in the same panel.

A Live-Cell Phosphoprotein Readout That Matches Lysate

Anti-phospho-BTK detection antibodies boosted into human PBMCs and read on a luminescent immunoassay. After pervanadate stimulation, the delivered-antibody arm reached about 80% of the lysate signal, with no-cargo controls near zero: pBTK signal mirrors lysate without permeabilization. Assay chemistry: Promega Lumit.

Delivery Holds Across Ten Consecutive Plates

Percent delivery for every well across ten consecutive 96-well plates of HeLa cells, boosted in line with the Powered-by-Portal Galaxy-i consumable on a Certus Flex dispenser. Delivery started near 100% and settled in the high 80s, holding between about 80% and 100% for the whole run. How much tracer gets in sets the BRET ratio, so this consistency keeps dose-response curves comparable from plate to plate. The approach scales directly to high-throughput screening on the Galaxy-i.

Upgrade Your Workflow

Run the NanoBRET target engagement assay you already use, on cells that are alive and intact. One pass through a MicroBooster™ cartridge puts an impermeable tracer and the compound into the cytosol together, so you read binding where the target actually sits.

Current Workflow Requires Permeable Tracers

Measuring target engagement traditionally requires making permeable tracers - which can take extra time and monetary investment.

01

Make permeable tracer

02

Make tracer permeable for cell-based target engagement

03

Run target engagement assay

Time Consuming

Portal has the Solution

01

Prepare

NanoLuc-tagged POI cells

02

Mix

Cells + tracer and compound

03

Boost

Gateway™ mechanoporation

04

Incubate

Allow signal to develop

05

Measure

Live-cell NanoBRET signal

Target engagement measured in live cells for any tracer

~20×

Live-cell BRET from a boosted impermeable Src tracer, against the same tracer unboosted

2.3×

Ubiquitination response for partially permeable degraders once delivered, in intact cells

80+%

Delivery held across ten consecutive 96-well plates of HeLa cells

What's in the Kit

The cargo and protocols below make this kit specific. The core consumables, settings, and support ship with every Portal kit.

Available Cargoes

You provide your: NanoBRET tracers; compounds and degraders; NanoLuc-tagged cells

Don't see your cargo? Ask us about custom configurations

Reagents & Consumables

Delivery tracer
MicroBooster™
Portal reagents

Protocol & Settings

NanoBRET protocol
Cartridge size and pressure per cell line
Recommended cell concentrations
Suggested assay readouts

Support

Assay setup with a Portal scientist
Optional: hands-on implementation visit

Available Cargoes

You provide your: NanoBRET tracers; compounds and degraders; NanoLuc-tagged cells

Don't see your cargo? Ask us about custom configurations

Reagents & Consumables

Delivery tracer
MicroBooster™
Portal reagents

Protocol & Settings

NanoBRET protocol
Cartridge size and pressure per cell line
Recommended cell concentrations
Suggested assay readouts

Support

Assay setup with a Portal scientist
Optional: hands-on implementation visit

Broad Compatibility

Portal’s platform supports delivery to a diverse range of cell types and cargoes

Delivery materials

Validated cell types

mRNA, siRNA, saRNA

Proteins & Peptides

CRISPR RNPs

Small Molecules

Polymers

Nanoparticles

Antibodies

Virus

PBMCs

T cells

B cells

NK cells

iPSCs

Monocytes

RBCs

HSCs

Delivery materials

mRNA, siRNA, saRNA

Proteins & Peptides

CRISPR RNPs

Small Molecules

Polymers

Nanoparticles

Antibodies

Virus

Validated cell types

PBMCs

T cells

B cells

NK cells

iPSCs

Monocytes

RBCs

HSCs

Check out our other kits

Validated live-cell workflows for target engagement, compound profiling, and beyond.

Every kit includes: Cargoes · Optimized protocols · MicroBooster™ cartridges · Suggested readouts · Reagents

Controllable Surface Receptor Expression

Solves: Fixed, hard-to-modulate surface antigen expression in cell lines
Cargo: Custom antigen/receptor RNA — single or combinations
Express any antigen on any cell in hours
e.g. CD19+CD3, BCMA+CD3, HER2+CD3

Live-Cell Protein Detection

Solves: Live-cell context lost to lysis, and target labeling that requires cell engineering.
Cargo: Intracellular antibodies (primary & secondary)
Measure endogenous intracellular proteins in live cells
e.g. p-BTK, p-ERK, p-AKT, p-STAT3, p-MET Compatible with LgBiT/HgBiT reagents

Direct-to-Assay Kit

Solves: The stable-line bottleneck: infeasible in primary cells, slow and laborious elsewhere
Cargo: Custom RNA encoding tagged POI
Run NanoBRET or LgBiT/HgBiT without stable lines
e.g. VHL-NanoLuc, HgBiT-tagged POI

Intracellular DEL Screening

Solves: DEL screens can't be done in live human cells
Cargo: Your DEL library
Screen intracellular targets with no library bias
e.g. iPSCs, HeLa, PBMCs - any cell type

Impermeable Candidate Validation in Live Cells

Solves: Permeability engineering as a prerequisite for testing cellular activity
Cargo: Your impermeable drug candidate
Validate and test your candidates in live cells, regardless of permeability
e.g. small molecules, macrocycles, peptides

What is the Live-Cell Target Engagement Kit?The Live-Cell Target Engagement Kit is a Portal Bio workflow kit for delivering NanoBRET tracers, chemical probes, and compounds into living cells so target engagement can be measured without digitonin permeabilization and without lysis. Gateway™ mechanoporation opens each cell by mechanical deformation as it passes a MicroBooster™ cartridge, the cargo diffuses into the cytosol, and the cell reseals. The kit supplies the MicroBooster™ cartridges, a fluorescent delivery tracer, Portal reagents, a Portal-style NanoBRET protocol, and an optional hands-on implementation visit; you bring your own tracers, compounds, and NanoLuc-tagged cells.

How do you measure target engagement in live cells without digitonin or lysis?Deliver the tracer mechanically instead of chemically. A NanoBRET target engagement assay needs a fluorescent tracer bound to a NanoLuc-tagged target inside the cell, and most tracers for intracellular targets do not cross into the cytosol on their own, which is why the standard workaround is digitonin permeabilization or a lysate readout. Gateway™ mechanoporation puts the tracer in through a transient mechanical opening rather than a detergent, so the assay reports on the target in its intracellular context: still folded, still carrying its binding partners and post-translational modifications, and the same cells can be read over time rather than at a single lysed endpoint.

What is a NanoBRET target engagement assay?A NanoBRET target engagement assay measures whether a compound binds its target inside a cell. The target is expressed as a NanoLuc fusion, a fluorescent tracer binds the same pocket, and energy transfer from NanoLuc to the bound tracer produces a BRET signal. Adding a competing compound displaces the tracer and the BRET ratio falls, so the dose-response curve reports occupancy of the target in a cellular setting rather than binding in a tube. The limiting step is getting the tracer inside, which is what the Live-Cell Target Engagement Kit handles.

Can you deliver membrane-impermeable NanoBRET tracers into live cells?Yes. A membrane-impermeable Src kinase tracer boosted into HeLa cells expressing NanoLuc-Src gave about 20× the BRET signal of the same tracer on unboosted cells, which stayed at baseline at every concentration tested. Ponatinib then displaced the tracer dose-dependently, cutting the signal about 35% at 1.1 µM, about 55% at 3.3 µM, and about 80% at 10 µM. Bosutinib reached about 85% displacement at 10 µM.

Do I need a NanoLuc-tagged cell line to run this kit?The NanoBRET readout needs a NanoLuc-tagged target, and the Live-Cell Target Engagement Kit is made for cells you have already tagged, whatever cell line they are. Building a tagged line conventionally runs about 2 to 5 months and $12K to $40K+ per target. If your target is not tagged yet, that is covered by a separate Portal kit rather than by this one: the Direct-to-Assay Kit boosts RNA encoding the tagged protein of interest and expresses it transiently within hours, including in primary and hard-to-transfect cells where a stable line is not realistic. Both kits run the same Gateway™ boost, so a protocol worked out on one carries to the other.

Can I profile PROTACs and molecular glues with this kit?Yes. In a NanoBRET degrader mechanism-of-action panel run with a pharma partner, two partially permeable compounds increased cellular ubiquitination of the target protein about 2.3-fold once delivered, while DMSO showed no significant difference. Ternary complex formation and proteasome recruitment increased to the same extent in the same panel. One of the partially permeable compounds scored more potent than the permeable control after delivery.

Can target engagement be measured in primary cells?Yes. Mechanoporation is a physical delivery step that does not depend on a cell being transfectable, so primary cells are in scope. In published work, eight poorly permeable JAK inhibitors were delivered into human primary PBMCs by mechanoporation; across five of them p-STAT5 fell to roughly 10 to 35% of control, against roughly 70 to 100% for the same compounds added without a delivery step. For the fluorescently labelled probe in that set, electroporation produced a fluorescence signal but no functional inhibition, while mechanoporation gave both (Li et al., 2017, ACS Chem Biol). Portal has also boosted whole PBMCs at over 70% delivery per subtype, so T cells, B cells, NK cells, and monocytes can all be screened in the same experiment.

Ready to run the Live-Cell Target Engagement Kit?

Request the kit and a Portal scientist will spec it for your cells, your tracer, and your readout.