Fig. 1
The dFlpTag system enables constitutive and conditional protein tagging and cell labeling. (A) The dFlpTag-attB constructs comprise attB sites, FRT3 and FRT sites, a protein trap (PT) module containing MHC splice acceptor (SA) and splice donor (SD) sites and a GFP reporter for protein tagging, as well as a 5xUAS and mtdTomato coding sequence for GAL4-driven cell labeling. The entire dFlpTag cassette can be integrated into a genomic locus of a gene of interest by swapping a MiMIC or CRIMIC cassette through recombinase-mediated cassette exchange (RMCE). The PT module allows for constitutive tagging of the protein of interest if the dFlpTag cassette aligns with gene transcription. If the dFlpTag cassette is integrated in a reversed orientation, the PT module can be reversed through FLP-mediated FRT and FRT3 recombination and is subsequently activated for conditional protein tagging. Meanwhile, mtdTomato ORF lies downstream of UAS promotor and can be expressed by a GAL4 driver for cell labeling. (B) Schematic illustration of dFlpTag application in the Drosophila central nervous system. A synaptic protein is transported to a specific neuropil, which is typically innervated by multiple neuronal types. By combining the conditional tagging strain with GAL4 drivers and either UAS-FLP or hs-FLP, both the target protein and its source cells can be labeled.
