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bioRxiv · 10.1101/2025.11.02.686167

Signaling bias of the protease-activated receptor-1 is dictated by distinct GRK5 and β-arrestin-2 determinants

Gonzalez Ramirez, M. L.·Orduna-Castillo, L. B.·Bardeleben, C.·Qin, H.·Lin, Y.·Birch, C. A.·Kufareva, I.·Trejo, J.
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Abstract

G protein-coupled receptors (GPCRs) exhibit signaling bias, or preferential activation of heterotrimeric G proteins versus GPCR receptor kinase (GRK)-mediated {beta}-arrestin signaling. The protease-activated receptor-1 (PAR1) GPCR activates both G protein and {beta}-arrestin in response to thrombin, but only {beta}-arrestin in response to activated protein C (APC). Thrombin-activated PAR1-G protein signaling is desensitized by {beta}-arrestin-1, whereas APC-activated PAR1 signaling is propagated by {beta}-arrestin-2. The mechanisms underlying PAR1 biased signaling are not known. Here, using computational modeling and cell biology studies, we reveal the molecular basis of signaling by thrombin- and APC-activated PAR1. Although both thrombin- and APC-induced PAR1 signaling are regulated by the same GRK isoform, GRK5, the two types of signaling are differentially dependent on GRK5 membrane anchoring, PAR1 C-terminal phosphorylation, and the binding mode of {beta}-arrestin-2. These differences translate into distinct {beta}-arrestin-2 conformations and define the cytoprotective signaling signature by APC which contrasts with thrombin inflammatory signaling.

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Gonzalez Ramirez, M. L., Orduna-Castillo, L. B., Bardeleben, C., Qin, H., Lin, Y., Birch, C. A., Kufareva, I., Trejo, J.. 2025-11-03. Signaling bias of the protease-activated receptor-1 is dictated by distinct GRK5 and β-arrestin-2 determinants. https://doi.org/10.1101/2025.11.02.686167

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