Formation of a ternary complex among NHERF1, beta-arrestin, and parathyroid hormone receptor.
β-Arrestins are crucial regulators of G-protein coupled receptor (GPCR) signaling, desensitization, and internalization. Despite the long-standing paradigm that agonist-promoted receptor phosphorylation is required for β-arrestin2 recruitment, emerging evidence suggests that phosphorylation-independent mechanisms play a role in β-arrestin2 recruitment by GPCRs. Several PDZ proteins are known to interact with GPCRs and serve as cytosolic adaptors to modulate receptor signaling and trafficking. Na(+)/H(+) exchange regulatory factors (NHERFs) exert a major role in GPCR signaling. By combining imaging and biochemical and biophysical methods we investigated the interplay among NHERF1, β-arrestin2, and the parathyroid hormone receptor type 1 (PTHR). We show that NHERF1 and β-arrestin2 can independently bind to the PTHR and form a ternary complex in cultured human embryonic kidney cells and Chinese hamster ovary cells. Although NHERF1 interacts constitutively with the PTHR, β-arrestin2 binding is promoted by receptor activation. NHERF1 interacts directly with β-arrestin2 without using the PTHR as an interface. Fluorescence resonance energy transfer studies revealed that the kinetics of PTHR and β-arrestin2 interactions were modulated by NHERF1. These findings suggest a model in which NHERF1 may serve as an adaptor, bringing β-arrestin2 into close proximity to the PTHR, thereby facilitating β-arrestin2 recruitment after receptor activation.
Klenk
Christoph
C
Institute of Pharmacology and Toxicology, University of Würzburg, 97078 Würzburg, Germany.
Vetter
Thorsten
T
Zürn
Alexander
A
Vilardaga
Jean-Pierre
JP
Friedman
Peter A
PA
Wang
Bin
B
Lohse
Martin J
MJ
D000818:Animals; D019390:Arrestins / Q000235:genetics / Q000378:metabolism*; D016466:CHO Cells; D006224:Cricetinae; D003412:Cricetulus; D006801:Humans; D046912:Multiprotein Complexes / Q000235:genetics / Q000378:metabolism*; D010750:Phosphoproteins / Q000235:genetics / Q000378:metabolism*; D020836:Protein Structure, Quaternary; D044168:Receptor, Parathyroid Hormone, Type 1 / Q000235:genetics / Q000378:metabolism*; D015398:Signal Transduction / Q000502:physiology; D017923:Sodium-Hydrogen Exchangers / Q000235:genetics / Q000378:metabolism*; D000071557:beta-Arrestins
D019390:Arrestins; D046912:Multiprotein Complexes; C473449:PTH1R protein, human; D010750:Phosphoproteins; D044168:Receptor, Parathyroid Hormone, Type 1; D017923:Sodium-Hydrogen Exchangers; D000071557:beta-Arrestins; C093376:sodium-hydrogen exchanger regulatory factor