BRET-Based Ligand Binding at Recombinant and Endogenous Dopamine D2 Receptors

Three far-red fluorescent antagonists—CELT-240, CELT-383, and CELT-385—enable BRET-based dopamine D2 receptor binding in living cells with nanomolar affinity and saturable, specific binding.

• Why it matters: Robust quantification of D2R ligand binding in living cells is needed, but BRET assays have been limited by a lack of suitable fluorescent D2R tracers.
• What they did: The authors developed CELT-240, CELT-383, and CELT-385 as BRET tracers and characterized CELT-385 for kinetic and competition binding, then used bystander BRET to measure unmodified recombinant and endogenously expressed D2R.
• The result: CELT-385 supports kinetic/competition measurements and shows high-affinity binding at dopamine D3 receptor, and bystander BRET extends D2R binding quantification to endogenous GPCR contexts.