Claing, APerry, SJAchiriloaie, MWalker, JKAlbanesi, JPLefkowitz, RJPremont, RT2013-09-052000-02-010027-8424https://hdl.handle.net/10161/7812Recently, we identified a GTPase-activating protein for the ADP ribosylation factor family of small GTP-binding proteins that we call GIT1. This protein initially was identified as an interacting partner for the G protein-coupled receptor kinases, and its overexpression was found to affect signaling and internalization of the prototypical beta(2)-adrenergic receptor. Here, we report that GIT1 overexpression regulates internalization of numerous, but not all, G protein-coupled receptors. The specificity of the GIT1 effect is not related to the type of G protein to which a receptor couples, but rather to the endocytic route it uses. GIT1 only affects the function of G protein-coupled receptors that are internalized through the clathrin-coated pit pathway in a beta-arrestin- and dynamin-sensitive manner. Furthermore, the GIT1 effect is not limited to G protein-coupled receptors because overexpression of this protein also affects internalization of the epidermal growth factor receptor. However, constitutive agonist-independent internalization is not regulated by GIT1, because transferrin uptake is not affected by GIT1 overexpression. Thus, GIT1 is a protein involved in regulating the function of signaling receptors internalized through the clathrin pathway and can be used as a diagnostic tool for defining the endocytic pathway of a receptor.Adaptor Proteins, Signal TransducingAnimalsCOS CellsCell Cycle ProteinsCells, CulturedCercopithecus aethiopsCyclic AMPEndocytosisGTP-Binding ProteinsGTPase-Activating ProteinsHumansPhosphoproteinsReceptor, Angiotensin, Type 1Receptor, Angiotensin, Type 2Receptor, Endothelin BReceptors, Adrenergic, betaReceptors, AngiotensinReceptors, Cell SurfaceReceptors, EndothelinReceptors, MuscarinicReceptors, Opioid, muReceptors, Vasoactive Intestinal PeptideRecombinant Fusion ProteinsTransfectionJournal article