Figure 1.

An assay to distinguish between Ty5 integration and recombination events. The Ty5 donor element is on a URA3-based vector. Ty5 cDNA is reverse transcribed, using mRNA from the donor element, which reconstitutes a functional HIS3 gene. The cDNA can either integrate into the host genome or recombine with the donor element to give rise to His⁺ cells. These events can be distinguished, because cells with plasmid Ty5 recombination events cannot grow on SC-H+FOA media due to the presence of the URA3 gene.