ISOLATION AND QUANTITATION OF M-FACTOR, A DIFFUSIBLE MATING FACTOR FROM THE FISSION YEAST SCHIZOSACCHAROMYCES-POMBE

Although there have been several reports demonstrating the existence of mating factors in the fission yeast Schizosaccharomyces pombe it has not been possible to isolate these factors as cell-free preparations. Such an ability is the first requirement towards a molecular characterization of these factors and here I report the successful isolation of a mating factor from S. pombe. This factor, termed M-factor, is released by cells of the cellular mating type M (Minus) and induces mating-specific changes in P-type cells. A reliable and accurate assay for the quantitation of the M-factor, based upon changes in cell volume following exposure to the factor, is also described.