MATING-TYPE GENE SWITCHING IN SACCHAROMYCES-CEREVISIAE

The study of yeast mating-type (MAT) gene switching bas provided insights into several aspects of the regulation of gene expression. MAT switching is accomplished by a highly programmed site-specific homologous recombination event ix which mating-type-specific sequences at MAT are replaced by alternative DNA sequences copied from one of two unexpressed donors. The mating-type system bas also provided ax opportunity to study both the genetic regulation of gene silencing by alterations in chromatin structure, and the basis of preferential recombination between a recipient of genetic information and one of several possible donors.