Purification and genetic control of α-pheromone-inactivating glycoproteins in the yeast Saccharomyces cerevisiae.

Two kinds of a-mating-type-specific proteins inactivating α pheromone (α factor) were purified from heat shock extract of MATa cells. Their molecular weights were estimated to be 400,000 and 200,000 by gel filtration. Both proteins were detected in MATa SST1 cells but not in MATα SST1, MATa sst1-1 and MATa/MATα SST1/SST1 cells. In addition, the proteins were detected in matα2-1 SST1 cells but not in matα1-2 SST1 cells. From these results, it is concluded that these proteins are synthesized under the control of the SST1 gene and responsible for the Barrier action of MATa cells. The relationship of these proteins to the secreted Barrier protein having a higher molecular weight is discussed.