ROLE OF YEAST INSULIN-DEGRADING ENZYME HOMOLOGS IN PROPHEROMONE PROCESSING AND BUD SITE SELECTION

The Saccharomyces cerevisiae AXL1 gene product Axl1p shares homology w ith the insulin-degrading enzyme family of endoproteases. Yeast axl1 m utants showed a defect in a-factor pheromone secretion, and a probable site of processing by Axl1p was identified within the a-factor precur sor. In addition, Axl1p appears to function as a morphogenetic determi nant for axial bud site selection. Amino acid substitutions within the presumptive active site of Axl1p caused defects in propheromone proce ssing but failed to perturb bud site selection. Thus, Axl1p has been s hown to participate in the dual regulation of distinct signaling pathw ays, and a member of the insulinase family has been implicated in prop eptide processing.