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.