Dopamine Receptors
Dopamine receptors, which belong to a large family of G protein-coupled receptors, are targets for a variety of drugs involved in diseases like schizophrenia, Parkinson’s disease, depression, and many others. This makes these receptors an attractive choice for research and developing methods that would help in understanding receptor function and signalling is the focus of our workgroup. There are five different subtypes of dopamine receptors, which are in turn divided into two subfamilies. D1-type receptors (D1 and D5) primary interact with Gs/olf -proteins, while D2-type family (D2, D3 and D4) acts via Gi/o-proteins. In order to study both subfamilies we have developed human embryonic kidney cell lines (HEK293) stably expressing human dopamine D1, D2L or D3 receptors (Reinart-Okugbeni et al. 2012) to use as a source of receptors for radioligand binding assay. This assay system has been applied to characterize the affinity and selectivity of novel dopaminergic compounds (Reinart-Okugbeni et al. 2013, Dzirkale et al. 2013). We are also using these stable cell lines in cAMP biosensor-based assay to determine the efficacies and potencies of new compounds (Mazina et al. 2015, Reinart-Okugbeni et al. 2013, Dzirkale et al. 2013) and in fluorescence microscopy experiments (Figure 1). For example, we have used HEK293 cells expressing dopamine D3 receptors in epifluorescence microscopy imaging for deep-learning-based ligand binding quantification (Allikalt et al. 2020, Tahk et al. 2023).
Additionally, we have successfully obtained budded baculovirus particles, containing either dopamine D1 or D3 receptors, which we use in fluorescence anisotropy measurements (Figure 1) (Allikalt et al. 2018, Tahk et al. 2023). We have also shown that budded baculovirus particles can be used as a source of receptors in radioligand binding experiments (Allikalt and Rinken 2017). Although overexpression systems are often used to study receptor-ligand interactions, we also have the know-how to perform ligand binding experiments with native tissues (Tekko et al. 2017).
Additionally, we have successfully obtained budded baculovirus particles, containing either dopamine D1 or D3 receptors, which we use in fluorescence anisotropy measurements (Figure 1) (Allikalt et al. 2018, Tahk et al. 2023). We have also shown that budded baculovirus particles can be used as a source of receptors in radioligand binding experiments (Allikalt and Rinken 2017). Although overexpression systems are often used to study receptor-ligand interactions, we also have the know-how to perform ligand binding experiments with native tissues (Tekko et al. 2017).
Figure 1. Using fluorescent ligands to study dopamine receptors in fluorescence anisotropy based assay or in fluorescence microscopy experiments. Both of these methods allow to easily measure ligand binding in real-time.