Multiple topological domains mediate subtype-specific internalization of the M2 muscarinic acetylcholine receptor.
نویسندگان
چکیده
Endocytosis of agonist-activated G protein-coupled receptors (GPCRs) is required for both resensitization and recycling to the cell surface as well as lysosomal degradation. Thus, this process is crucial for regulation of receptor signaling and cellular responsiveness. Although many GPCRs internalize into clathrin-coated vesicles in a dynamin-dependent manner, some receptors, including the M(2) muscarinic acetylcholine receptor (mAChR), can also exhibit dynamin-independent internalization. We have identified five amino acids, located in the sixth and seventh transmembrane domains and the third intracellular loop, that are essential for agonist-induced M(2) mAChR internalization via a dynamin-independent mechanism in JEG-3 choriocarcinoma cells. Substitution of these residues into the M(1) mAChR, which does not internalize in these cells, is sufficient for conversion to the internalization-competent M(2) mAChR phenotype, whereas removal of these residues from the M(2) mAChR blocks internalization. Cotransfection of a dominant-negative isoform of dynamin has no effect on M(2) mAChR internalization. An internalization-incompetent M(2) mutant that lacks a subset of the necessary residues can still internalize via a G protein-coupled receptor kinase-2 and beta-arrestin-dependent pathway. Furthermore, internalization is independent of the signal transduction pathway that is activated. These results identify a novel motif that specifies structural requirements for subtype-specific dynamin-independent internalization of a GPCR.
منابع مشابه
Two homologous phosphorylation domains differentially contribute to desensitization and internalization of the m2 muscarinic acetylcholine receptor.
Short term exposure of m2 muscarinic acetylcholine receptors (m2 mAChRs) to agonist causes a rapid phosphorylation of the activated receptors, followed by a profound loss in the ability of the m2 mAChR to activate its signaling pathways. We have used site-directed mutagenesis to identify two clusters of Ser/Thr residues in the third intracellular loop of the m2 mAChR that can serve as redundant...
متن کاملMUSCARINIC RECEPTOR SUBTYPES IN SMOOTH MUSCLE FROM THE BODY OF HUMAN STOMACH
Up to date, there are four pharmacologically characterized subtypes of muscarinic receptors (M1, M2, M3 and M4). In our study we have investigated muscarinic receptor subtypes in smooth muscle layers of human stomach. Isolated preparations of longitudinal and circular muscle layers from human stomach were used. Acetylcholine, bethanechol, carbachol, pilocarpine and AHR -602 produced concen...
متن کاملRACK1 Associates with Muscarinic Receptors and Regulates M2 Receptor Trafficking
Receptor internalization from the cell surface occurs through several mechanisms. Some of these mechanisms, such as clathrin coated pits, are well understood. The M(2) muscarinic acetylcholine receptor undergoes internalization via a poorly-defined clathrin-independent mechanism. We used isotope coded affinity tagging and mass spectrometry to identify the scaffolding protein, receptor for activ...
متن کاملInternalization of the M2 muscarinic acetylcholine receptor proceeds through an atypical pathway in HEK293 cells that is independent of clathrin and caveolae.
The M2 muscarinic acetylcholine receptor is a G-protein coupled receptor that undergoes agonist-induced internalization through an unidentified pathway that exhibits an atypical dependence on dynamin function in HEK293 cells. In this report we utilized several independent approaches to reveal that the internalization of the M2 muscarinic acetylcholine receptor did not utilize clathrin-coated pi...
متن کاملDistribution of m1-m4 muscarinic receptor proteins in the rat striatum: light and electron microscopic immunocytochemistry using subtype-specific antibodies.
Muscarinic ACh receptors mediate complex and clinically important effects in the striatum. To better understand the roles of the different muscarinic receptor subtypes (m1-m4), we have determined the cellular and subcellular distribution of the m1-m4 receptor proteins in the rat neostriatum using subtype-specific antibodies and avidin-biotin-peroxidase immunocytochemistry for light and electron...
متن کاملذخیره در منابع من
با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید
عنوان ژورنال:
- The Journal of biological chemistry
دوره 275 30 شماره
صفحات -
تاریخ انتشار 2000