Authors
Gonzalez Ramirez, M. L., Orduna-Castillo, L. B., Bardeleben, C., Qin, H., Lin, Y., Birch, C. A., Kufareva, I., Trejo, J.
Abstract
G protein-coupled receptors (GPCRs) exhibit signaling bias, or preferential activation of heterotrimeric G proteins versus GPCR receptor kinase (GRK)-mediated B-arrestin signaling. The protease-activated receptor-1 (PAR1) GPCR activates both G protein and B-arrestin in response to thrombin, but only B-arrestin in response to activated protein C (APC). Thrombin-activated PAR1-G protein signaling is desensitized by B-arrestin-1, whereas APC-activated PAR1 signaling is propagated by B-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 B-arrestin-2. These differences translate into distinct B-arrestin-2 conformations and define the cytoprotective signaling signature by APC which contrasts with thrombin inflammatory signaling.
Preprint server:
bioRxiv
The authors list and abstract were imported from bioRxiv on 04 Nov 2025.
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