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

Of the mutations that result in a soluble form of Kexlp (Kexlp-Xho, -AS, and -AMS), Kexlp-AS is the most informative with regard to determining which domain(s) of Kexlp is involved in its localization. Kexlp-AS is secreted, yet contains all but 11 residues of the 596-residue lumenal domain (Fig. 3) . The 11 residues absent in Kexlp-AS are present in Kexlp-AMS which is also secreted. The results suggest that either the membrane-spanning or cytoplasmic domain, or both, are responsible for the retention of Kexlp within the Golgi apparatus.