Functional tagging of endogenous proteins and rapid selection of cell pools (Rapid generation of endogenously tagged piwi in ovarian somatic sheath cells.)
The combination of genome-editing and epitope tagging provides a powerful strategy to study proteins with high affinity and specificity while preserving their physiological expression patterns. However, stably modifying endogenous genes in cells that do not allow for clonal selection has been challenging. Here, we present a simple and fast strategy to generate stable, endogenously tagged alleles in a non-transformed cell culture model. At the example of piwi in Drosophila ovarian somatic sheath cells, we show that this strategy enables the generation of an N-terminally tagged protein that emulates the expression level and subcellular localization of the wild type protein and forms functional Piwi-piRNA complexes. We present a concise workflow to establish modified cells, characterize the edited allele and probe the function of the tagged protein.