Accessory Proteins in the Biogenesis of G Protein-Coupled Receptors

GPCR association with transmembrane accessory proteins in the ER. A summary of the GPCR–protein interactions that are discussed in the text. 1) The GABA^BR1 receptor associates with homologous GABA^BR2 in forming the heterodimer (shown exiting the ER) required for vesicular transport to the cell surface. 2) An odorant GPCR has been shown to associate with ODR-4, an essential type II membrane-anchored protein. 3) Receptors CRLR and Drosophila rhodopsin require association with type I membrane proteins, such as RAMPs and NinaA, respectively. 4) The dopamine D1 receptor binds to DRiP78 (possessing two internal transmembrane domains) in coordinating ER export.