Signaling Specificity in Yeast

The signaling pathways in yeast that control mating and filamentous growth are extremely similar and share many of the same components, yet the signals almost never get mixed up. One reason, revealed in a Perspective by Elion and colleagues, is that activation of one of the proteins in the mating pathway leads to degradation of a key transcription factor that lies at the end of the filamentous growth pathway. Thus, even though some signal does leak from one pathway to another, the insulation is sufficient to prevent interference between two very different cellular programs.