Protease with a carboxypeptidase B-like function involved in the C-terminal processing of the lysine and arginine residues from the precursors of K1, K2 and K28 killer toxins and a-factor (mating pheromone). Involved in the programmed cell death caused by defective N-glycosylation and contributes also to the active cell death program induced by acetic acid stress or during chronological aging. Promotes cell fusion by proteolytically processing substrates that act in parallel to PRM1 as an alternative fusion machine, as cell wall components, or both. Preferential release of a C-terminal arginine or lysine residue. Present with 8550 molecules/cell in log phase SD medium. Belongs to the peptidase S10 family.