Fluorescent tools for the imaging of dopamine D2-like receptors

Martin Nagl, Denise Mönnich, Niklas Rosier, Hannes Schihada, Alexei Sirbu, Nergis Konar, Irene Reyes-Resina, Gemma Navarro, Rafael Franco, Peter Kolb, Paolo Annibale, Steffen Pockes*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review


The family of dopamine D2-like receptors represents an interesting target for a variety of neurological diseases, e. g. Parkinson's disease (PD), addiction, or schizophrenia. In this study we describe the synthesis of a new set of fluorescent ligands as tools for visualization of dopamine D2-like receptors. Pharmacological characterization in radioligand binding studies identified UR-MN212 (20) as a high-affinity ligand for D2-like receptors (pKi (D2longR)=8.24, pKi (D3R)=8.58, pKi (D4R)=7.78) with decent selectivity towards D1-like receptors. Compound 20 is a neutral antagonist in a Go1 activation assay at the D2longR, D3R, and D4R, which is an important feature for studies using whole cells. The neutral antagonist 20, equipped with a 5-TAMRA dye, displayed rapid association to the D2longR in binding studies using confocal microscopy demonstrating its suitability for fluorescence microscopy. Furthermore, in molecular brightness studies, the ligand's binding affinity could be determined in a single-digit nanomolar range that was in good agreement with radioligand binding data. Therefore, the fluorescent compound can be used for quantitative characterization of native D2-like receptors in a broad variety of experimental setups.
Original languageEnglish
Article numbere202300659
Number of pages15
VolumeEarly View
Early online date20 Nov 2023
Publication statusE-pub ahead of print - 20 Nov 2023


  • Confocal microscopy
  • D2-like receptors
  • Dopamine receptors
  • Fluorescent ligands
  • Molecular brightness


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