An asymmetric system of pheromone recognition in fission yeast.

The specificity of recognition of M-factor (lipid peptide) is extremely stringent, whereas that of the P-factor (simple peptide) is relatively relaxed, allowing cross-reactions to occur between two yeast species. Therefore, the diversity of the two mating pheromones might facilitate asymmetrically in nature. This possession of distinctly different specificities for the mating pheromones might guarantee not only stringent recognition of mating partners but also flexible adaptation to various mutational changes in a combination of a pheromone/receptor. M, Minus; P, Plus.