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Key phosphorylation sites in GPCRs orchestrate the contribution of ?-Arrestin 1 in ERK1/2 activation

ABSTRACT: ?-arrestins (?arrs) are key regulators of GPCR signaling and trafficking, and their knockdown typically leads to a decrease in agonist-induced ERK1/2 MAP kinase activation. Interestingly, for some GPCRs, knockdown of ?arr1 augments agonist-induced ERK1/2 phosphorylation although a mechanistic basis for this intriguing phenomenon is unclear. Here, we use selected GPCRs to explore a possible correlation between the spatial positioning of receptor phosphorylation sites and the contribution of ?arr1 in ERK1/2 activation. We discover that engineering a spatially positioned double-phosphorylation-site cluster in the bradykinin receptor (B2R), analogous to that present in the vasopressin receptor (V2R), reverses the contribution of ?arr1 in ERK1/2 activation from inhibitory to promotive. An intrabody sensor suggests a conformational mechanism for this role-reversal of ?arr1, and molecular dynamics simulation reveals a bifurcated salt-bridge between this double phosphorylation site cluster and Lys294 in the lariat loop of ?arr1, which directs the orientation of the lariat loop. Our findings provide novel insights into the opposite roles of ?arr1 in ERK1/2 activation for different GPCRs with a direct relevance to biased agonism and novel therapeutics.

SUBMITTER: Prof. Arun, Kumar Shukla

PROVIDER: S-SCDT-EMBOR-2019-49886V1P | biostudies-other |

REPOSITORIES: biostudies-other

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