beta2-Adrenergic receptor regulation by GIT1, a G protein-coupled receptor kinase-associated ADP ribosylation factor GTPase-activating protein.
G protein-coupled receptor activation leads to the membrane recruitment and activation of G protein-coupled receptor kinases, which phosphorylate receptors and lead to their inactivation. We have identified a novel G protein-coupled receptor kinase-interacting protein, GIT1, that is a GTPase-activating protein (GAP) for the ADP ribosylation factor (ARF) family of small GTP-binding proteins. Overexpression of GIT1 leads to reduced beta2-adrenergic receptor signaling and increased receptor phosphorylation, which result from reduced receptor internalization and resensitization. These cellular effects of GIT1 require its intact ARF GAP activity and do not reflect regulation of GRK kinase activity. These results suggest an essential role for ARF proteins in regulating beta2-adrenergic receptor endocytosis. Moreover, they provide a mechanism for integration of receptor activation and endocytosis through regulation of ARF protein activation by GRK-mediated recruitment of the GIT1 ARF GAP to the plasma membrane.
Premont
R T
RT
Departments of Medicine (Cardiology) and Biochemistry, Howard Hughes Medical Institute, Box 3821, Duke University Medical Center, Durham, NC 27710, USA.
Claing
A
A
Vitale
N
N
Freeman
J L
JL
Pitcher
J A
JA
Patton
W A
WA
Moss
J
J
Vaughan
M
M
Lefkowitz
R J
RJ
D020727:ADP-Ribosylation Factors; D048868:Adaptor Proteins, Signal Transducing; D000595:Amino Acid Sequence; D000818:Animals; D001665:Binding Sites; D002417:Cattle; D018797:Cell Cycle Proteins; D002460:Cell Line; D002462:Cell Membrane / Q000378:metabolism; D017868:Cyclic AMP-Dependent Protein Kinases / Q000378:metabolism*; D054769:G-Protein-Coupled Receptor Kinase 2; D019204:GTP-Binding Proteins / Q000378:metabolism; D020690:GTPase-Activating Proteins; D015870:Gene Expression; D006801:Humans; D007700:Kinetics; D008297:Male; D008969:Molecular Sequence Data; D009928:Organ Specificity; D010750:Phosphoproteins; D011506:Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D018343:Receptors, Adrenergic, beta-2 / Q000502:physiology*; D011994:Recombinant Proteins / Q000378:metabolism; D012374:Rod Cell Outer Segment / Q000378:metabolism; D018411:Spodoptera; D014162:Transfection; D051552:beta-Adrenergic Receptor Kinases
D048868:Adaptor Proteins, Signal Transducing; D018797:Cell Cycle Proteins; C485647:GIT1 protein, human; D020690:GTPase-Activating Proteins; D010750:Phosphoproteins; D011506:Proteins; D018343:Receptors, Adrenergic, beta-2; D011994:Recombinant Proteins; D017868:Cyclic AMP-Dependent Protein Kinases; C496567:GRK2 protein, human; D051552:beta-Adrenergic Receptor Kinases; D054769:G-Protein-Coupled Receptor Kinase 2; D019204:GTP-Binding Proteins; D020727:ADP-Ribosylation Factors