Cytosolic Hsp70s are involved in the transport of aminopeptidase 1 from the cytoplasm into the vacuole.
Eukaryotic 70 kDa heat shock proteins (Hsp70s) are localized in various cellular compartments and exhibit functions such as protein translocation across membranes, protein folding and assembly. Here we demonstrate that the constitutively expressed members of the yeast cytoplasmic Ssa subfamily, Ssa1/2p, are involved in the transport of the vacuolar hydrolase aminopeptidase 1 from the cytoplasm into the vacuole. The Ssap family members displayed overlapping functions in the transport of aminopeptidase 1. In SSAI and SSAII deletion mutants the precursor of aminopeptidase 1 accumulated in a dodecameric complex that is packaged in prevacuolar transport vesicles. Ssa1/2p was prominently localized to the vacuolar membrane, consistent with the role we propose for Ssa proteins in the fusion of transport vesicles with the vacuolar membrane.
Satyanarayana
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C
Institut für Molekulare Zellbiologie und Biochemie, Abteilung Biochemie II, Universität Göttingen, Heinrich-Düker Weg 12, D-37073, Göttingen, Germany.
Schröder-Köhne
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S
Craig
E A
EA
Schu
P V
PV
Horst
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M
D000251:Adenosine Triphosphatases; D000626:Aminopeptidases / Q000737:chemistry / Q000378:metabolism*; D016282:Aspartic Acid Endopeptidases / Q000235:genetics / Q000378:metabolism; D001692:Biological Transport; D003593:Cytoplasm / Q000378:metabolism*; D004792:Enzyme Precursors / Q000737:chemistry / Q000378:metabolism; D005455:Fluorescent Antibody Technique; D005656:Fungal Proteins / Q000235:genetics / Q000502:physiology*; D017353:Gene Deletion; D005800:Genes, Fungal / Q000235:genetics / Q000502:physiology; D018840:HSP70 Heat-Shock Proteins / Q000235:genetics / Q000502:physiology*; D018869:Heat-Shock Response; D007425:Intracellular Membranes / Q000378:metabolism; D008970:Molecular Weight; D010587:Phagocytosis; D011485:Protein Binding; D012441:Saccharomyces cerevisiae / Q000166:cytology / Q000201:enzymology / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins; D014617:Vacuoles / Q000378:metabolism*
D004792:Enzyme Precursors; D005656:Fungal Proteins; D018840:HSP70 Heat-Shock Proteins; C542288:SSA2 protein, S cerevisiae; C090869:SSA3 protein, S cerevisiae; D029701:Saccharomyces cerevisiae Proteins; D000626:Aminopeptidases; C019689:APE1 protein, S cerevisiae; D016282:Aspartic Acid Endopeptidases; C022442:aspergillopepsin II; D000251:Adenosine Triphosphatases; C095973:SSA1 protein, S cerevisiae