Green flies

In the December 18 Proceedings of the National Academy of Sciences, Morin et al. describe a gene-trap strategy that generates green fluorescent protein (GFP) fusions and allows the study of protein distribution and subcellular localization in living flies (Proc Natl Acad Sci USA 2001, 98:15050-15055). They created a protein-trap transposon (PTT), a P element containing an artificial exon encoding GFP and flanked by splice acceptor and donor sequences. They derived over 600 fluorescent Drosophila lines and observed fusion proteins localized in a range of cellular organelles. Characterization of several of these revealed that in most cases splicing occurred correctly and fusions recapitulated endogenous expression of the trapped gene. Over 40% of characterized lines correspond to genes that were not predicted by the Drosophila Genome Project.