P4-ATPase requirement for AP-1/clathrin function in protein transport from the trans-Golgi network and early endosomes.

Department of Biological Sciences, Vanderbilt University, Nashville, TN 37235-1634, USA.
Drs2p is a resident type 4 P-type ATPase (P4-ATPase) and potential phospholipid translocase of the trans-Golgi network (TGN) where it has been implicated in clathrin function. However, precise protein transport pathways requiring Drs2p and how it contributes to clathrin-coated vesicle budding remain unclear. Here we show a functional codependence between Drs2p and the AP-1 clathrin adaptor in protein sorting at the TGN and early endosomes of Saccharomyces cerevisiae. Genetic criteria indicate that Drs2p and AP-1 operate in the same pathway and that AP-1 requires Drs2p for function. In addition, we show that loss of AP-1 markedly increases Drs2p trafficking to the plasma membrane, but does not perturb retrieval of Drs2p from the early endosome back to the TGN. Thus AP-1 is required at the TGN to sort Drs2p out of the exocytic pathway, presumably for delivery to the early endosome. Moreover, a conditional allele that inactivates Drs2p phospholipid translocase (flippase) activity disrupts its own transport in this AP-1 pathway. Drs2p physically interacts with AP-1; however, AP-1 and clathrin are both recruited normally to the TGN in drs2Delta cells. These results imply that Drs2p acts independently of coat recruitment to facilitate AP-1/clathrin-coated vesicle budding from the TGN.
Mesh Terms:
Alleles, Biological Transport, Calcium-Transporting ATPases, Cell Membrane, Clathrin, Endosomes, Exocytosis, Gene Expression Regulation, Fungal, Golgi Apparatus, Green Fluorescent Proteins, Lipid Bilayers, Models, Biological, Saccharomyces cerevisiae, Saccharomyces cerevisiae Proteins, Transcription Factor AP-1, trans-Golgi Network
Mol. Biol. Cell Aug. 01, 2008; 19(8);3526-35 [PUBMED:18508916]
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