Novel dopamine D2 receptor signaling through proteins interacting with the third cytoplasmic loop

Area of Science:

• Neuroscience
• Molecular Biology
• Pharmacology

Background:

• Dopamine D2-like receptors (D2, D3, D4) mediate diverse cellular functions.
• Protein interactions with the third cytoplasmic loop regulate receptor signaling, trafficking, and apoptosis.
• Two isoforms of the dopamine D2 receptor (D2L and D2S) exist, differing in the third cytoplasmic loop.

Purpose of the Study:

• To review novel functions of hetero-oligomeric D1/D2 and D2/adenosine A2A receptors.
• To discuss novel signaling pathways involving proteins interacting with the D2 receptor's third cytoplasmic loop.
• To define the function of heart-type fatty acid binding protein as a D2L interacting protein.

Main Methods:

• Literature review focusing on dopamine receptor signaling.
• Analysis of protein-protein interactions at the D2 receptor third cytoplasmic loop.
• Examination of novel receptor heteromers and binding proteins.

Main Results:

• Proteins like calmodulin, NMDAR2B, CaMKII, P-REX2, and β-arrestins interact with the D2 receptor loop, modulating signaling and pharmacology.
• The D2S receptor isoform lacks 29 amino acids in the third cytoplasmic loop compared to D2L.
• Novel functions of D1/D2 and D2/adenosine A2A heteromers are highlighted.
• Heart-type fatty acid binding protein identified as a novel interactor with the D2L third cytoplasmic loop.

Conclusions:

• Protein interactions with the D2 receptor third cytoplasmic loop are critical for its diverse functions.
• Investigating novel heteromers and interacting proteins like heart-type fatty acid binding protein offers new insights into D2 receptor pharmacology and signaling.