Alpha Ligand-receptor Assays
Ligand:receptor assays can be designed to measure the direct interaction of a ligand and a receptor, or a functional response triggered through agonist-mediated receptor activation. Direct ligand-binding can be studied using a recombinant, soluble portion of your receptor in biochemical assay. Cell surface receptors as well as nuclear receptors can be studied. We offer many types of beads as standard catalog products that can be used to bind to an antibody specific for your receptor, or to His-tagged, c-myc-tagged, GST-tagged, or biotinylated receptors, etc. We offer unconjugated beads that can be used to directly-conjugate any molecule of interest (for example, an antibody) to a bead. We also offer custom bead conjugation services.
Figure 1. Example of the assay design for a TNFα ligand-TNFα receptor binding assay.
You could also design your assay to measure the functional response of the receptor upon activation by the ligand. For a functional assay, we offer the AlphaScreen® cAMP kit as well as our Alpha SureFire® kits. The AlphaScreen cAMP kit measures the activation of Gi-coupled or Gs-coupled GPCRs by measuring changes in levels of cellular cAMP. The Alpha SureFire® assays can be used to measure downstream signaling events (phosphorylation of targets involved in various signaling cascades), following stimulation of a cell-surface receptor. Both of these assays are cell-based assays that involve cell lysis. If you are interested either of these functional assays, please view the AlphaScreen cAMP or Alpha SureFire® pages for more information.
What do I need to run this assay?
For direct ligand-receptor binding assays, the follow list includes required reagents available from PerkinElmer:
- Alpha Donor beads (that can associate with one of the binding partners, either the ligand or the receptor)
- AlphaScreen or AlphaLISA Acceptor beads (that can associate with the other binding partner)
- Microplates - We recommend our 96-well 1/2 AreaPlates or our 384-well white OptiPlates™. Also see Microplate selection.
- TopSeal™-A adhesive plate seal for incubations
- A plate reader capable of reading Alpha assays
Alpha products and catalog numbers
View a listing of Alpha products with catalog numbers.
For detailed information on assay design and development, view our Create your own Alpha assay page.
Application notes and tech notes
- Application note for a TNFα ligand-receptor binding assay. This assay uses a recombinant, soluble portion of the TNFα receptor in a ligand-binding biochemical assay. The kit referenced in this application note is currently only offered as a custom kit; however, it is possible to recreate this exact assay using information in the application note.
- Technical note for an AlphaScreen estrogen receptor assay.
View a brief list of citations for Alpha ligand-receptor assays.
Tips and FAQs
- Information on determining a Kd in Alpha format.
Q. Can I bind a cell membrane to a bead? If so, what is the best way to do this?
A. You will need to test this for your particular assay. We have captured membranes for Alpha assays using lectin-coated beads (wheat germ agglutinin, concanavalin A, etc.). We can custom conjugate beads to be coated with WGA and ConA.
Q. Can I work with tissues or crude membrane preparations?
A. You will need to test this for your particular assay. We have used lectin-coated beads in the past to capture membrane. You may also be able to tag or biotinylate your membrane and use an appropriate affinity bead to capture your tissue.
View our general Alpha troubleshooting tips.
Custom bead conjugation and custom assay development at PerkinElmer
PerkinElmer offers custom bead conjugation services as well as custom assay development. If you are interested in having your biomolecule custom-conjugated to a bead, or in custom assay development, please contact our custom teams: