Optochemical profiling of receptor-proximal proteins in vivo in minutes

Abstract

Understanding how protein-protein interaction networks in the brain give rise to cognitive functions necessitates their characterization in live animals. However, tools available for this purpose require potentially disruptive genetic modifications and lack the temporal resolution necessary to track rapid changes in vivo. Here, we combined ligand-directed chemistry and photocatalyzed singlet oxygen generation to identify neurotransmitter receptor-proximal proteins in the live mouse brain using only small-molecule reagents and minutes of photoirradiation. Named PhoxID (photooxidation-driven proximity labeling for proteome identification), our method not only recapitulated the known interactomes of two endogenous neurotransmitter receptors (AMPAR and GABAAR) but also uncovered age-dependent shifts, identifying NECTIN3 and IGSF3 as developmentally regulated AMPAR-proximal proteins in the cerebellum. Overall, this work establishes a flexible and generalizable platform to study receptor microenvironments in genetically intact specimens with an unprecedented temporal resolution.