Transport of a large oligomeric protein by the cytoplasm to vacuole protein targeting pathway.
Aminopeptidase I (API) is transported into the yeast vacuole by the cytoplasm to vacuole targeting (Cvt) pathway. Genetic evidence suggests that autophagy, a major degradative pathway in eukaryotes, and the Cvt pathway share largely the same cellular machinery. To understand the mechanism of the Cvt import process, we examined the native state of API. Dodecameric assembly of precursor API in the cytoplasm and membrane binding were rapid events, whereas subsequent vacuolar import appeared to be rate limiting. A unique temperature-sensitive API-targeting mutant allowed us to kinetically monitor its oligomeric state during translocation. Our findings indicate that API is maintained as a dodecamer throughout its import and will be useful to study the posttranslational movement of folded proteins across biological membranes.
Kim
J
J
Section of Microbiology, University of California, Davis 95616, USA.
Scott
S V
SV
Oda
M N
MN
Klionsky
D J
DJ
D000626:Aminopeptidases / Q000378:metabolism*; D001343:Autophagy; D001692:Biological Transport; D003593:Cytoplasm / Q000378:metabolism; D005656:Fungal Proteins / Q000378:metabolism; D007425:Intracellular Membranes / Q000378:metabolism; D046911:Macromolecular Substances; D011498:Protein Precursors / Q000378:metabolism*; D017433:Protein Structure, Secondary; D012441:Saccharomyces cerevisiae / Q000201:enzymology / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins; D017384:Sequence Deletion; D014617:Vacuoles / Q000201:enzymology / Q000378:metabolism
D005656:Fungal Proteins; D046911:Macromolecular Substances; D011498:Protein Precursors; D029701:Saccharomyces cerevisiae Proteins; D000626:Aminopeptidases; C019689:APE1 protein, S cerevisiae