A stable plasmid carrying the yeast Leu2 gene and containing only yeast deoxyribonucleic acid

The plasmid pSLe1 is a deletion derivative of the yeast-Escherichia coli hybrid plasmid pJDB219, obtained by HindIII digestion, ligation, and transformation directly into Saccharomyces cerevisiae. pSLe1 has only yeast sequences; it contains one of the inverted repeated sequences of plasmid 2muDNA and the LEU2 gene. pSLe1 is stably maintained in yeast cells without selective pressure. pSLe1 is about half as large as 2muDNA, but pSLe1 does not displace the normal 2muDNA.