WORKFLOW KIT · ASSAY DEVELOPMENT

Direct-to-Assay Kit

Boost RNA encoding a tagged protein of interest into your cells and run NanoBRET or LgBiT/HiBiT the same day.

Kits include: Custom cargoes · Optimized protocols · Portal reagents · Delivery cartridges · Suggested readouts

Upgrade Your Workflow

Boost mRNA encoding a NanoLuc-tagged protein into your cells and read target engagement on a NanoBRET plate the same day, with a full dose-response in one run. No stable line, and no digitonin. The same boost also delivers LgBiT protein for live-cell degradation assays.

The Current Workflow is Broken

A NanoBRET or LgBiT/HiBiT assay normally starts with a cell line that stably expresses the tagged protein of interest. Cloning, transfection, selection and expansion take months per target, and you’re restricted to cell lines that transfect well — primary and hard-to-transfect cells are out. Using lysate or permeabilizing with digitonin avoids the cell line, but eliminates the live-cell intracellular context that made the assay worth running.

01

Design tagged construct

02

Generate stable cell line

03

Wait weeks

04

Run assay

Dead End

Portal has the Solution

01

Prepare

Cells of choice, no stable line

02

Mix

Cells + RNA encoding tagged POI

03

Boost

Gateway™ mechanoporation

04

Express

Tagged POI within hours

05

Assay

NanoBRET or LgBiT/HiBiT

Assay-ready cells in hours

1 day

To assay-ready cells, against months to build a stable cell line

Any cell

Cell lines, primary cells, and hard-to-transfect cells — no stable line to build

96- or 384-well plates

96- or 384-well plates, boosted in line on an existing dispenser with Galaxy-i

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

NanoLuc-tagged POI (e.g. VHL-NanoLuc)
HiBiT-tagged POI
HA-tagged POI
Other tags on request

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

Reagents & Consumables

Delivery tracer
MicroBooster™
Portal reagents

Protocol & Settings

NanoBRET protocol
LgBiT/HiBiT protocol
Recommended cell concentrations
Suggested readouts

Support

Portal RNA sourcing
Optional: hands-on implementation visit

Available Cargoes

NanoLuc-tagged POI (e.g. VHL-NanoLuc)
HiBiT-tagged POI
HA-tagged POI
Other tags on request

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

Reagents & Consumables

Delivery tracer
MicroBooster™
Portal reagents

Protocol & Settings

NanoBRET protocol
LgBiT/HiBiT protocol
Recommended cell concentrations
Suggested readouts

Support

Portal RNA sourcing
Optional: hands-on implementation visit

Proof Points

NanoBRET Target Engagement in AsPC-1 Cells From Boosted VHL-NanoLuc mRNA

Merck boosted mRNA encoding VHL-NanoLuc into AsPC-1 cells at 1×10⁶ cells and 10 µg mRNA. Luminescence came back around 600 times the non-boosted control, showing the tagged protein reached working levels. A BODIPY tracer bound VHL-NanoLuc and produced a BRET signal at 618 nm, and titrating the competitive VHL ligand VH298 displaced it in a dose-response that reached full effect at 10 µM. The assay usually requires a stably expressing VHL-NanoLuc line for each target; here it ran without one, saving the time and cost of building it. (Merck, 2026 Portal drug discovery whitepaper.)

Quantifying Endogenous KRAS(G12C) in Live Cells With Boosted LgBiT Protein

MiaPaCa-2 cells carrying a HiBiT tag knocked into the endogenous KRAS(G12C) locus were boosted with Promega's LgBiT protein. LgBiT and HiBiT complement inside the cell to reconstitute an active luciferase, so endogenous KRAS is quantified by luminescence without lysis. The G12C-specific degrader LC-2 reduced the signal dose-dependently over 24 hours, to roughly 40% of the 0 µM arm at 1 µM, 25% at 5 µM and 10% at 10 µM. Untreated, no-boost and no-cargo controls all sat at baseline. (Promega collaboration.)

Degradation Kinetics Read Continuously in Live Cells, Without Digitonin

A HiBiT/LgBiT pair tracked protein-of-interest levels continuously over 22 hours of degrader treatment. Signal in non-boosted cells plateaued at about 60% of the DMSO control, while boosted cells reached about 15%. Boosting bypasses the degrader’s own permeability, so the difference reflects degradation rather than uptake, and the live-cell format supports a continuous kinetic read. (Merck.)

mRNA Expression in Unstimulated Primary T Cells and iPSCs

A single boost of GFP mRNA reached most live unstimulated primary human T cells, and iPSCs too, with viability largely preserved — both are notoriously delicate to engineer. The RNA is unmodified: the boost drops it into the cytosol rather than through an endosome, so it expresses without base modification. (Hirsch et al., Keystone 2023 and 2024.)

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 Antigen 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

Live-Cell Target Engagement

Solves: Live-cell context lost to lysis and detergents, and the need to create cell-permeable tracers
Cargoes: Your tracers (e.g. NanoBRET) and compounds
Enables live-cell target engagement without lysis; supports impermeable tracers
e.g. kinase inhibitor profiling, degrader engagement

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 Direct-to-Assay Kit?The Direct-to-Assay Kit is a Portal Bio workflow kit for expressing a tagged protein of interest in live cells without building a stable cell line, so NanoBRET and LgBiT/HiBiT assays can be run quickly. Gateway™ mechanoporation opens each cell by mechanical deformation, RNA encoding the tagged POI diffuses into the cytosol, and the cell reseals. The kit supplies custom RNA encoding your tagged POI (NanoLuc, HiBiT, HA and other tags), a delivery tracer, MicroBooster™ cartridges, NanoBRET and LgBiT/HiBiT protocols, recommended cell concentrations and suggested readouts. Assay-ready cells take 1 day, instead of building a stable cell line.

Can you run a NanoBRET assay without a stable cell line?Yes. In NanoBRET, a NanoLuc luciferase is fused to the protein of interest and a fluorescent tracer binds at the same site; a competing compound displaces the tracer and the signal drops. That fusion normally has to come from a stable line. Boosting mRNA that encodes the NanoLuc-tagged protein into your cells replaces the stable line. Boosting mRNA that encodes the NanoLuc-tagged protein expresses it within hours, and the tracer, VH298 competitor and readout run as usual. Nothing was cloned, selected or expanded, so the assay is not restricted to cell lines that transfect well.

Can I run LgBiT/HiBiT assays in live cells without lysing them?Yes. LgBiT protein can be boosted directly into cells that carry a HiBiT tag, where the two halves complement to reconstitute an active NanoLuc luciferase and report protein levels by luminescence without lysis. In work with Promega, MiaPaCa-2 cells endogenously HiBiT-tagged at the KRAS(G12C) locus were boosted with LgBiT protein and treated for 24 hours with the G12C-specific degrader LC-2. Signal fell dose-dependently to roughly 40% of the 0 µM arm at 1 µM, 25% at 5 µM and 10% at 10 µM, while untreated, no-boost and no-cargo controls stayed at baseline. Conventional LgBiT/HiBiT detection requires lysis or an established LgBiT-expressing line.

Does mechanoporation give the same NanoBRET result as digitonin permeabilization?Yes, in the comparison Merck ran. Mechanoporated VHL-NanoLuc mRNA produced a BRET profile similar to the digitonin-permeabilized control, and both modes approached full effect at the higher VH298 concentrations. The difference is what survives the measurement: digitonin and lysis destroy the native intracellular environment and give an endpoint snapshot, while boosted cells stay alive and can be read continuously. For degradation kinetics specifically, a HiBiT/LgBiT trace ran for 22 hours on live boosted cells.

Can I use this kit for targeted protein degradation and PROTAC assays?Yes, and it is one of the applications the kit was validated on. Two routes exist. In the first, VHL-NanoLuc mRNA is boosted in and a BODIPY tracer and a VH298 titration reported degrader binding to VHL, the degrader permeability assay run without its usual stable line. In the second, a HiBiT-tagged POI is read against boosted LgBiT protein, either as an endpoint (LC-2 against endogenous KRAS(G12C) in MiaPaCa-2 cells) or as a kinetic trace. In that kinetic run the boosted arm reached about 15% of DMSO control vs about 60% for non-boosted, over 22 hours.

Does the kit work in 96- and 384-well plates for high-throughput screening?The kit itself runs on Gateway™, the benchtop research system. For plate-scale work the same boosting can be run in line on Galaxy-i, a consumable that retrofits dispensers already on the bench, including the HighRes PreciseDrop II, the nNano/Gyger Certus Flex, the ONF System and the Integra WellJet. Cells pass through the cartridge as they are dispensed into wells pre-loaded with cargo. One cartridge covers roughly 5 to 10 plates.

Ready to run the Direct-to-Assay Kit?

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