Abstract
Background The adenosine A2A receptor (A2AR) heteromerizes with the dopamine D2 receptor (D2R). In order to explore their functional interaction, we engineered previously stable single-polypeptide-chain (sc) A2AR/D2LR: whether the molecular entity of the striatal A2AR/D2R antagonism, i.e., scA2AR/D2Rs are just A2AR/D2R with the antagonism, remains unresolved.
New Method To further clarify the heteromerization through the scA2AR/D2LR, we here designed supramolecularly ‘exclusive’ monomers and dimers, using the Cε2 domain of IgE-Fc or apoproteins of the bacterial light-harvesting antenna complex.
Results A concept of the recptor protein assembly regulation, i.e., the selective monomer/non-obligate dimer formation was obtained. Although none of these new fusions were constructed or tested, we could aim at obtaining heterodimer-specific agents, using the scA2AR/D2R. Whether the resulting designs were explained feasibly and rationally was addressed. The structure and function of the non-obligate dimer were here discussed through scA2AR/D2R, focusing on the procedure of the membrane protein design and methods for transient protein-protein interactions.
Summary and Outlook Given that upon being expressed and allosteric regulation occurs regardless of specific signal to non-specific noise (S/N) ratio, the supramolecular designs, allowing us to express selectively monomer/non-obligate dimer of class A GPCR, are experimentally testable and will be used to confirm in vivo that such low S/N ratio interaction between A2AR and D2LR functions in the dopamine neurotransmission in the striatum.
- A2AR
- adenosine A2A receptor
- 3HA-A2AR
- A2AR tagged with a triple HA epitope
- Bchl
- bacteriochlorophyll
- BRET
- bioluminescence resonance energy transfer
- C
- carboxy-terminal
- CD
- cluster of differentiation
- D2LR and D2SR
- the long and short form of dopamine D2 receptor, respectively
- Fab
- antigen binding fragment
- Fc
- Fc fragment
- FcεRI
- high affinity receptor for IgE
- FRET
- fluorescence resonance energy transfer
- G4S
- an amino acid sequence consisting of a four-glycine-repeat followed by a serine residue
- GABA
- γ-aminobutyric acid
- GABAB
- GABA type B receptor
- GPCR
- G protein-coupled receptor
- Gt
- transducin
- HA
- hemagglutinin
- HIV
- human immunodeficiency virus
- IC
- intracellular loops
- Ig
- immunoglobulin
- LH
- light-harvesting antenna complex
- mAb
- monoclonal antibody
- Mr
- molecular weight
- N
- amino-terminal
- PD
- Parkinson’s disease
- PS
- photosystem
- RC
- reaction center
- Rluc
- Renilla luciferase
- sc
- single-chain
- TM
- transmembrane
- 3D
- three-dimensional
