Yeast Kex1p is a Golgi-associated membrane protein: deletions in a cytoplasmic targeting domain result in mislocalization to the vacuolar membrane

S ~.CREa'EO biologically active proteins and peptides are classically produced as precursors which undergo both endo-and exoproteolytic processing to release the mature species while traversing the secretory pathway. The KEX/gene product (Kexlp) is a carboxypeptidase, specific for basic amino acid residues, and is responsible for processing proteins secreted by Saccharomyces cerevisiae (Dmochowska et al., 1987; Cooper and Bussey, 1989) . In conjunction with the proteases Kex2p and dipeptidyl aminopeptidase A (DPAP A) ~ (Stel3p), Kexlp proteolytically matures proteins such as c~-factor and K1 killer toxin from their precursors (for reviews see Bussey, 1988; Fuller et al., 1988) .