Either one of the two yeast EF-1? genes is required for cell viability

Abstract
Summary Two genes,TEF1 andTEF2, encode the protein elongation factor EF-1α in the yeastSaccharomyces cerevisiae. We have generated yeast haploid strains containing eitherTEF1 orTEF2 interrupted by insertion of a large piece of foreign DNA. Cells which contain either one functional copy of the EF-1α genes are viable. In contrast, attempts to isolate a yeast haploid strain with bothTEF1 andTEF2 inactivated have failed suggesting that the double gene disruption is a lethal event.