title: Potent and Selective Peptide-based Inhibition of the G Protein Gαq.
abstract: In contrast to G protein-coupled receptors, for which chemical and peptidic inhibitors have been extensively explored, few compounds are available that directly modulate heterotrimeric G proteins. Active Gαqbinds its two major classes of effectors, the phospholipase C (PLC)-β isozymes and Rho guanine nucleotide exchange factors (RhoGEFs) related to Trio, in a strikingly similar fashion: a continuous helix-turn-helix of the effectors engages Gαqwithin its canonical binding site consisting of a groove formed between switch II and helix α3. This information was exploited to synthesize peptides that bound active Gαqin vitro with affinities similar to full-length effectors and directly competed with effectors for engagement of GαqA representative peptide was specific for active Gαqbecause it did not bind inactive Gαqor other classes of active Gα subunits and did not inhibit the activation of PLC-β3 by Gβ1γ2In contrast, the peptide robustly prevented activation of PLC-β3 or p63RhoGEF by Gαq; it also prevented G protein-coupled receptor-promoted neuronal depolarization downstream of Gαqin the mouse prefrontal cortex. Moreover, a genetically encoded form of this peptide flanked by fluorescent proteins inhibited Gαq-dependent activation of PLC-β3 at least as effectively as a dominant-negative form of full-length PLC-β3. These attributes suggest that related, cell-penetrating peptides should effectively inhibit active Gαqin cells and that these and genetically encoded sequences may find application as molecular probes, drug leads, and biosensors to monitor the spatiotemporal activation of Gαqin cells.
authors.affiliation: From the Departments of Pharmacology and.|Lineberger Comprehensive Cancer Center, University of North Carolina School of Medicine, Chapel Hill, North Carolina 27599.
authors.forename: Thomas H
authors.initials: TH
authors.lastname: Charpentier
authors.affiliation: From the Departments of Pharmacology and.
authors.forename: Gary L
authors.initials: GL
authors.lastname: Waldo
authors.affiliation: From the Departments of Pharmacology and.
authors.forename: Emily G
authors.initials: EG
authors.lastname: Lowery-Gionta
authors.affiliation: Biochemistry and Biophysics.|High-Throughput Peptide Synthesis and Array Facility, and.
authors.forename: Krzysztof
authors.initials: K
authors.lastname: Krajewski
authors.affiliation: Biochemistry and Biophysics.|High-Throughput Peptide Synthesis and Array Facility, and.
authors.forename: Brian D
authors.initials: BD
authors.lastname: Strahl
authors.affiliation: From the Departments of Pharmacology and.
authors.forename: Thomas L
authors.initials: TL
authors.lastname: Kash
authors.affiliation: From the Departments of Pharmacology and.
authors.forename: T Kendall
authors.initials: TK
authors.lastname: Harden
authors.affiliation: From the Departments of Pharmacology and sondek@med.unc.edu.|Lineberger Comprehensive Cancer Center, University of North Carolina School of Medicine, Chapel Hill, North Carolina 27599.|Biochemistry and Biophysics.
authors.forename: John
authors.initials: J
authors.lastname: Sondek
mesh_terms: D000818:Animals; D057846:Cell-Penetrating Peptides / Q000737:chemistry* / Q000494:pharmacology*; D043802:GTP-Binding Protein alpha Subunits, Gq-G11 / Q000037:antagonists & inhibitors* / Q000235:genetics / Q000378:metabolism; D044387:GTP-Binding Protein beta Subunits / Q000235:genetics / Q000378:metabolism; D044388:GTP-Binding Protein gamma Subunits / Q000235:genetics / Q000378:metabolism; D057809:HEK293 Cells; D006801:Humans; D051379:Mice; D054799:Phospholipase C beta / Q000235:genetics / Q000378:metabolism; D017397:Prefrontal Cortex / Q000378:metabolism*; D017433:Protein Structure, Secondary
chemical_list: D057846:Cell-Penetrating Peptides; D044387:GTP-Binding Protein beta Subunits; D044388:GTP-Binding Protein gamma Subunits; D054799:Phospholipase C beta; D043802:GTP-Binding Protein alpha Subunits, Gq-G11
keywords: G protein; inhibitor; p63; peptide interaction; phospholipase C