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Proc Natl Acad Sci U S A. 2017 Sep 19;114(38):10095-10100. doi: 10.1073/pnas.1708810114. Epub 2017 Sep 5.

Stachel-independent modulation of GPR56/ADGRG1 signaling by synthetic ligands directed to its extracellular region.

Author information

1
Biophysical Sciences Program, The University of Chicago, Chicago, IL 60637.
2
Medical Scientist Training Program, The University of Chicago, Chicago, IL 60637.
3
Department of Biochemistry and Molecular Biology, The University of Chicago, Chicago, IL 60637.
4
Perlmutter Cancer Center, New York University Langone Medical Center, New York, NY 10016.
5
Department of Medicine, New York University School of Medicine, New York, NY 10016.
6
Perlmutter Cancer Center, New York University Langone Medical Center, New York, NY 10016; Shohei.Koide@nyumc.org arac@uchicago.edu.
7
Department of Biochemistry and Molecular Pharmacology, New York University School of Medicine, New York, NY 10016.
8
Department of Biochemistry and Molecular Biology, The University of Chicago, Chicago, IL 60637; Shohei.Koide@nyumc.org arac@uchicago.edu.
9
Grossman Institute for Neuroscience, Quantitative Biology and Human Behavior, The University of Chicago, Chicago, IL 60637.

Abstract

Adhesion G protein-coupled receptors (aGPCRs) play critical roles in diverse biological processes, including neurodevelopment and cancer progression. aGPCRs are characterized by large and diverse extracellular regions (ECRs) that are autoproteolytically cleaved from their membrane-embedded signaling domains. Although ECRs regulate receptor function, it is not clear whether ECRs play a direct regulatory role in G-protein signaling or simply serve as a protective cap for the activating "Stachel" sequence. Here, we present a mechanistic analysis of ECR-mediated regulation of GPR56/ADGRG1, an aGPCR with two domains [pentraxin and laminin/neurexin/sex hormonebinding globulin-like (PLL) and G protein-coupled receptor autoproteolysis-inducing (GAIN)] in its ECR. We generated a panel of high-affinity monobodies directed to each of these domains, from which we identified activators and inhibitors of GPR56-mediated signaling. Surprisingly, these synthetic ligands modulated signaling of a GPR56 mutant defective in autoproteolysis and hence, in Stachel peptide exposure. These results provide compelling support for a ligand-induced and ECR-mediated mechanism that regulates aGPCR signaling in a transient and reversible manner, which occurs in addition to the Stachel-mediated activation.

KEYWORDS:

adhesion GPCR; allostery; cell signaling; monobody; protein engineering

PMID:
28874577
PMCID:
PMC5617296
DOI:
10.1073/pnas.1708810114
[Indexed for MEDLINE]
Free PMC Article

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