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

The mechanism for targeting of the type I transmembrane carboxypeptidase Kex1p to the Golgi aparatus was investigated. Kex1p is involved in precursor processing in the yeast secretory pathway. The study protocol involved the examination of the cellular location of a series ofcarboxy-terminal truncations of the carboxypeptidase. The results showed that the cytoplasmically exposed carboxy-terminal is required for retention of the carboxipeptidase in the Golgi apparatus. Deletion of the carboxy-terminal retention signal causes default localization to the vacuolar membrane.