| Modification Notes |
Autophagy is a membrane trafficking mechanism that delivers cytoplasmic cargo to the vacuole/lysosome for degradation and recycling. The proper functioning of eukaryotic organelles is largely dependent on the specific packaging of cargo proteins within transient delivery vesicles (1). The cytoplasm to vacuole targeting (Cvt) pathway is an autophagy-related trafficking pathway whose cargo proteins, aminopeptidase I and å-mannosidase, are selectively transported from the cytoplasm to the lysosome-like vacuole in yeast (1-3). In the budding yeast Saccharomyces cerevisiae, å-mannosidase, also known as AMP Deaminase or Ams1, is a marker enzyme of the vacuolar membrane (4,5). å-mannosidase has no typical signal sequence, but is located on the inner surface of the vacuolar membrane (4). The enzyme is synthesized as a polypeptide and is converted to a shorter polypeptide by the vacuolar processing protease, proteinase A (4). å-mannosidase forms an oligomer in the cytoplasm, however its mechanism of vacuolar delivery has not been established (5). Vacuolar localization of å-mannosidase is blocked in mutants that are defective in the Cvt and autophagy pathways (5). |