Controlled expression of tagged proteins in Drosophila using a new modular P-element vector system.

We have developed a new modular vector system that facilitates the combination of various DNA fragments as functional modules for P element-mediated transformation of Drosophila melanogaster. The basic vector pP¿GS¿ contains unique sites for 17 restriction enzymes, including three 8-bp cutters, that allow one to combine various promoter elements, cDNAs and genomic DNA fragments, as well as protein tags and selectable marker genes, for a wide spectrum of transgene analyses. With this new vector system we analysed the chromosomal distribution of the Drosophila SU(VAR)3-9 protein tagged with EGFP, using hsp70-cDNA and genomic Su(var)3-9 constructs. We found preferential association of the tagged SU(VAR)3-9 with centric heterochromatin.