AAV-mediated expression of TurboID protein in specific cell types in the mouse brain. A, The workflow of AAV-TurboID labeling. We used AAV-PHP.eB to package single-stranded recombinant AAV genomes that express TurboID tagged with FLAG at N-terminus and mCherry at C-terminus. The T2A sequence was inserted between TurboID and mCherry for self-cleavage. The cell type-specific expression was controlled by promoters. The recombinant viruses were delivered to mouse brains, followed by biotin administration and brain harvest for immunostaining and proteomic analyses. B, Detection of cell type-specific expression by co-translated mCherry throughout the brain. C, Double immunofluorescence staining shows the specificity of cell type-specific expression. NeuN and GFAP are cellular markers for neurons and astrocytes, respectively.