Response of Yeast   Cells to a-Factor Pheromone: Topology of the Receptor and Identification of a Component of the Response Pathway

Abstract

Haploid cells of the yeast Saccharomyces cerevisiae exhibit either of two complex cellular phenotypes, the mating types a or α. Each cell type reproduces vegetatively by a mitotic cell cycle. However, a sexual cycle is also possible: Cells of opposite mating type participate in a mating process that results in cell and nuclear fusion to create an a/α diploid cell (for review, see Thorner 1981; Sprague et al. 1983). The mating process is initiated by interaction of cell-type-specific peptide pheromones with unique receptors present on the surface of cells of the opposite mating type. Thus, α cells secrete α-factor, which affects only a cells, and a cells secrete a-factor, which acts only on α cells. The binding of pheromone to the receptor on the target cell is believed to create an intracellular signal(s) that induces a physiological response, which facilitates mating. The response includes changes in transcription of certain genes...