A general method for the chromosomal amplification of genes in yeast.

The yeast retrotransposon Ty can be used to insert multiple copies of a gene at new sites in the genome. The gene of interest is inserted into a GALI-Ty fusion construct; the entire "amplification cassette" is then introduced into yeast on a high copy number plasmid vector. Transposition of the Ty element carrying the gene occurs at multiple sites in the genome. Two genes, a bacterial neomycin phosphotransferase gene and the yeast TRPl gene, were amplified in this way. Although the amplified genes were about 1 kilobase in length, they were amplified to about the same extent as a 40-base pair segment. The benefit of this "shotgun" approach is that amplification can be achieved in one set of manipulations.