Cell-type–specific, multicolor labeling of endogenous proteins with split fluorescent protein tags in Drosophila

Significance Split fluorescent protein (FP) systems have been used to endogenously tag proteins in human cells. However, there have been a limited number of studies to evaluate the potential of multicolor FP 11 tags in organisms. Here, we implement the approach for FP 11 tagging proteins in Drosophila . We show the use of this approach in creating protein trap lines using MiMIC insertions and enhancing signals through a tandem array of tags. While split GFP has been practical, the availability of a second split FP enables multicolor visualization. Through bioengineering, we develop variants and show two-color FP 11 tagging, revealing the differential distribution of proteins in synapses. This approach is advantageous to examine the endogenous localization patterns of multiple proteins in particular cell types.