Cloning and characterization of LAG1, a longevity-assurance gene in yeast.
The yeast Saccharomyces cerevisiae has a finite life span that is measured by the number of times the individual cell divides. The gene coding for one of several transcripts that are differentially expressed during the replicative life span has been cloned. The nucleotide sequence revealed an open reading frame capable of encoding a transmembrane protein of 411 amino acids that displays no significant similarities to any known proteins. Nevertheless, sequences similar to this gene were found in several mammals, including humans. The transcript levels decreased with replicative age of yeast cells. A gene deletion in haploid cells resulted in a pronounced increase (approximately 50%) in mean and in maximum life span. These results indicate that this gene, which we call LAG1, plays a role in determining yeast longevity.