The brain vasculature is tightly regulated to control the exchange of substances between the periphery and the brain parenchyma at an interface called the blood-brain barrier (BBB). Astrocytes are glial cells that wrap the brain vasculature with a specialised structure called the endfoot, which is an integral component of the BBB. We generated adeno-associated viruses (AAVs) that express a promiscuous biotin ligase, TurboID, specifically in astrocytes, and developed a method that allows us to define the in vivo protein composition of the astrocyte endfoot with negligible contamination of other cells or other compartments of the astrocyte. Here, we isolated the biotinylated proteins from both the whole astrocyte and astrocyte endfeet from mice with acute peripheral inflammation.