Activation-dependent Conformational Changes in β-Arrestin 2*

By Kunhong Xiao, Sudha K. Shenoy, K. Nobles, R. J. Lefkowitz. Journal of Biological Chemistry, 2004

137 citations recorded by the source corpus.

β-Arrestins are multifunctional adaptor proteins, which mediate desensitization, endocytosis, and alternate signaling pathways of seven membrane-spanning receptors (7MSRs). Crystal structures of the basal inactive state of visual arrestin (arrestin 1) and β-arrestin 1 (arrestin 2) have been resolved. However, little is known about the conformational changes that occur in β-arrestins upon binding to the activated phosphorylated receptor. Here we characterize the conformational changes in β-arrestin 2 (arrestin 3) by comparing the limited tryptic proteolysis patterns and matrix-assisted laser desorption/ionization-time of flight mass spectrometry (MALDI-TOF MS) profiles of β-arrestin 2 in the presence of a phosphopeptide (V2R-pp) derived from the C terminus of the vasopressin type II receptor (V2R) or the corresponding nonphosphopeptide (V2R-np). V2R-pp binds to β-arrestin 2 specifically, whereas V2R-np does not. Activation of β-arrestin 2 upon V2R-pp binding involves the release of its C terminus, as indicated by exposure of a previously inaccessible cleavage site, one of the polar core residues Arg394, and rearrangement of its N terminus, as indicated by the shielding of a previously accessible cleavage site, residue Arg8. Interestingly, binding of the polyanion heparin also leads to release of the C terminus of β-arrestin 2; however, heparin and V2R-pp have different binding site(s) and/or induce different conformational changes in β-arrestin 2. Release of the C terminus from the rest of β-arrestin 2 has functional consequences in that it increases the accessibility of a clathrin binding site (previously demonstrated to lie between residues 371 and 379) thereby enhancing clathrin binding to β-arrestin 2 by 10-fold. Thus, the V2R-pp can activate β-arrestin 2 in vitro, most likely mimicking the effects of an activated phosphorylated 7MSR. These results provide the first direct evidence of conformational changes associated with the transition of β-arrestin 2 from its basal inactive conformation to its biologically active conformation and establish a system in which receptor-β-arrestin interactions can be modeled in vitro.

Subfields: Cellular and Molecular Neuroscience, Molecular Biology, Spectroscopy

View Paper: https://www.semanticscholar.org/paper/8cedd1355e038701a1608a65771415201a823c96

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Citations in the corpus

GRKs and β-arrestins: roles in receptor silencing, trafficking and signaling (2006, background): “Moreover, a recent in vitro study showing that a synthetic phosphorylated peptide derived from the carboxyterminus of the V2R binds to and induces conformational changes, as well as clathrin binding, in b-arrestin 2 supports this hypothesis [ 56 ].”
Molecular Mechanism of β-Arrestin-Biased Agonism at Seven-Transmembrane Receptors (2011, background): “Early in vitro studies used the patterns of limited tryptic proteolysis to demonstrate that β-arrestin 1 and 2 undergo conformational changes upon interaction with phosphorylated peptides mimicking those produced by the vasopressin type 2 receptor (V2R) C terminus (65, 66).”
Distinct Phosphorylation Sites on the β2-Adrenergic Receptor Establish a Barcode That Encodes Differential Functions of β-Arrestin (2011, background): “Synthetic phosphopeptides corresponding to the C-terminal sequences of two GPCRs bind to and induce conformational changes in b-arrestins (23, 24).”