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Molecular Basis For Activation And Biased Signaling At The Thrombin-Activated Gpcr Proteinase Activated Receptor-4 (Par4), Pierre E. Thibeault, Jordan C. Lesarge, D'Arcy Arends, Michaela Fernandes, Peter Chidiac, Peter B. Stathopulos, Leonard G. Luyt, Rithwik Ramachandran

Physiology and Pharmacology Publications

© 2020 Thibeault et al. Proteinase-activated receptor (PAR)-4 is a member of the proteolytically-activated PAR family of G-protein– coupled receptors (GPCR) that represents an important target in the development of anti-platelet therapeutics. PARs are activated by proteolytic cleavage of their receptor N terminus by enzymes such as thrombin, trypsin, and cathepsin-G. This reveals the receptor-activating motif, termed the tethered ligand that binds intramolecularly to the receptor and triggers signaling. However, PARs are also activated by exogenous application of synthetic peptides derived from the tethered-ligand sequence. To better understand the molecular basis for PAR4-dependent signaling, we examined PAR4-signaling responses to a …

Effects Of G Protein Signalling Modulator 3 On Cellular Signalling, Aneta A. Surmanski

Electronic Thesis and Dissertation Repository

G protein coupled receptors (GPCRs) promote G protein heterotrimer (Gα·GDP/Gbg) activation.GPCRsignalling is limited via G protein GTPase activity and b-arrestin-receptor interactions. G Protein Signalling Modulators (GPSMs) are proteins that may influence receptor signalling through G protein activity. GPSM3 modulates their activity by binding to Ga_i-GDP, limiting nucleotide exchange and preventing its re-association to Gbg. The impact of GPSM3 on signalling is unknown.We hypothesize that GPSM3 will decrease Ga_i-dependent signalling while promoting Gbg-dependent signalling in G_i-coupled GPCRs.

GPSM3 significantly inhibited b-arrestin recruitment to α_2A-adrenergic and m-opioid receptors via a Gbg-dependent mechanism, …