Membrane protein retention in the yeast Golgi apparatus: dipeptidyl aminopeptidase A is retained by a cytoplasmic signal containing aromatic residues

Replacement of the DPAP A transmembrane domain with a synthetic hydrophobic sequence, L(LALV)5, had no effect on the vacuolar delivery of retention-defective DPAP A, arguing that this domain does not contain a cryptic vacuolar targeting signal. Vacuolar targeting information is also unlikely to reside in the luminal domain of DPAP A since its replacement with that of DPAP B, a domain demonstrated to lack vacuolar targeting information, also had no effect on transport of mislocalized DPAP A to the vacuole (Roberts et al., 1992) . Finally, removal of almost the entire cytoplasmic domain of A-ALP (A2-100-A-ALP) resulted in its delivery to the vacuole, and thus it is unlikely that the DPAP A cytoplasmic domain contains both a Golgi retention signal and a cryptic vacuolar targeting signal. We conclude that vacuolar delivery of DPAP A protein not retained in the Golgi is not a signal mediated event and thus occurs by default.