AlphaLISA SureFire Ultra Human and Mouse Total ATF4 Detection Kit, 100 Assay Points

Total-AlphaLISA SureFire Ultra assay principle

The Total-AlphaLISA SureFire Ultra assay measures the expression level of a protein target in a cell lysate.

The Total-AlphaLISA SureFire Ultra assay uses two antibodies which recognize two different distal epitopes on the targeted protein. AlphaLISA assays require two bead types: Acceptor and Donor beads. Acceptor beads are coated with a proprietary CaptSure™ agent to specifically immobilize the assay specific antibody, labeled with a CaptSure tag. Donor beads are coated with streptavidin to capture one of the detection antibodies, which is biotinylated. In the presence of targeted protein, the two antibodies bring the Donor and Acceptor beads in close proximity whereby the singlet oxygen transfers energy to excite the Acceptor bead, allowing the generation of a luminescent Alpha signal. The amount of light emission is directly proportional to the quantity of protein present in the sample.

Total-AlphaLISA SureFire Ultra two-plate assay protocol

The two-plate protocol involves culturing and treating the cells in a 96-well plate before lysis, then transferring lysates into a 384-well OptiPlate™ plate before the addition of Total-AlphaLISA SureFire Ultra detection reagents. This protocol permits the cells viability and confluence to be monitored. In addition, lysates from a single well can be used to measure multiple targets.

Upregulation of ATF4 in Thapsigargin treated cells

A549 and RAW264.7 cells were seeded in a 96-well plate (40,000 cells/well) in complete medium, and incubated for 24 hours at 37°C, 5% CO2. Cells were treated with increasing concentrations of Thapsigargin for 4 hours.

After treatment, the cells were lysed with 100 µL of Lysis Buffer for 10 minutes at RT with shaking (350 rpm). ATF4 and Cofilin levels were evaluated using respective AlphaLISA SureFire Ultra assays. For the detection step, 10 µL of cell lysate (approximately 4,000 cells) was transferred into a 384-well white OptiPlate, followed by 5 µL of Acceptor mix and incubated for 1 hour at RT. Finally, 5 µL of Donor mix was then added to each well and incubated for 1 hour at RT in the dark. The plate was read on an Envision using standard AlphaLISA settings.

As expected, ATF4 expression is upregulated in response to Thapsigargin treatment, while Cofilin levels remained unchanged.

Induction of ATF4 in Tunicamycin treated cells

A549 and RAW264.7 cells were seeded in a 96-well plate (40,000 cells/well) in complete medium, and incubated for 24 hours at 37°C, 5% CO2. Cells were treated with increasing concentrations of Tunicamycin for 4 hours.

After treatment, the cells were lysed with 100 µL of Lysis Buffer for 10 minutes at RT with shaking (350 rpm). ATF4 and Cofilin levels were evaluated using respective AlphaLISA SureFire Ultra assays. For the detection step, 10 µL of cell lysate (approximately 4,000 cells) was transferred into a 384-well white OptiPlate, followed by 5 µL of Acceptor mix and incubated for 1 hour at RT. Finally, 5 µL of Donor mix was then added to each well and incubated for 1 hour at RT in the dark. The plate was read on an Envision using standard AlphaLISA settings.

As expected, ATF4 expression is upregulated in response to Tunicamycin treatment, while Cofilin levels remained unchanged.