Dopamine receptors – 7-transmembrane spanning, G-protein coupled receptors
There are four broad ‘superfamilies’ of receptor: (1) the channel-linked (ionotropic) receptors; (2) the G-protein coupled (metabotropic) receptors; (3) the kinase-linked receptors; and (4) receptors that regulate gene transcription. Dopamine receptors belong to the G-protein coupled superfamily. They are membrane receptors that have 7 transmembrane spanning a-helices. Dopamine binding to the ‘binding groove’ on the extracellular portion of the receptor activates the G-proteins, which initiate secondary messenger signalling pathways. The downstream effect will be either inhibitory or stimulatory, depending on the types of G-protein linked to the receptor – dopamine D1, D5 receptors are linked to inhibitory G-proteins, whereas dopamine D2, D3, D4 are linked to stimulatory G-proteins.
Click the image to view high resolution version
References
Introduction to autonomic pharmacology. In: Basic and clinical pharmacology, 8th edition. Katzung BG. USA: The McGraw Hill Companies, Inc, 2001:75–91.
How drugs act: molecular aspects. In: Pharmacology, 4th edition. Rang HP, Dale MM and Ritter JM. Edinburgh, UK: Harcourt Publishers Ltd, 2001:19–46.