The Functional Relationship between the Cdc50p-Drs2p Putative Aminophospholipid Translocase and the Arf GAP Gcs1p in Vesicle Formation in the Retrieval Pathway from Yeast Early Endosomes to the TGN

• Published in: Cell Structure and Function Vol. 31; no. 2; pp. 87 - 108
• Main Authors: Sakane, Hiroshi, Yamamoto, Takaharu, Tanaka, Kazuma
• Format: Journal Article
• Language: English
• Published: Japan Japan Society for Cell Biology 01-01-2006; Japan Science and Technology Agency
• Subjects: Adaptor Proteins, Vesicular Transport - genetics; Adaptor Proteins, Vesicular Transport - metabolism; ADP-Ribosylation Factor 1 - genetics; ADP-Ribosylation Factor 1 - metabolism; ADP-Ribosylation Factors - genetics; ADP-Ribosylation Factors - metabolism; Arf signaling; Calcium-Transporting ATPases - genetics; Calcium-Transporting ATPases - metabolism; Cathepsin A - metabolism; Chitin Synthase; Clathrin-Coated Vesicles - metabolism; Clathrin-Coated Vesicles - ultrastructure; DNA-Binding Proteins - genetics; DNA-Binding Proteins - metabolism; endocytic recycling; Endocytosis - physiology; Endosomes - metabolism; Endosomes - ultrastructure; Exocytosis - physiology; GTPase-Activating Proteins - genetics; GTPase-Activating Proteins - metabolism; Intracellular Membranes - metabolism; Intracellular Membranes - ultrastructure; Membrane Lipids - metabolism; Membrane Proteins - genetics; Membrane Proteins - metabolism; phospholipid asymmetry; Proprotein Convertases - genetics; Proprotein Convertases - metabolism; R-SNARE Proteins - genetics; R-SNARE Proteins - metabolism; Recombinant Fusion Proteins - genetics; Recombinant Fusion Proteins - metabolism; Saccharomyces cerevisiae - metabolism; Saccharomyces cerevisiae - ultrastructure; Saccharomyces cerevisiae Proteins - genetics; Saccharomyces cerevisiae Proteins - metabolism; Signal Transduction - physiology; trans-Golgi Network - metabolism; Transcription Factor AP-1 - genetics; Transcription Factor AP-1 - metabolism; Vacuoles - metabolism; Vesicular Transport Proteins - genetics; Vesicular Transport Proteins - metabolism; yeast
• ISSN: 0386-7196; 1347-3700
• DOI: 10.1247/csf.06021

Drs2p, the catalytic subunit of the Cdc50p-Drs2p putative aminophospholipid translocase, has been implicated in conjunction with the Arf1 signaling pathway in the formation of clathrin-coated vesicles (CCVs) from the TGN. Herein, we searched for Arf regulator genes whose mutations were synthetically lethal with cdc50Δ, and identified the Arf GAP gene GCS1. Most of the examined transport pathways in the Cdc50p-depleted gcs1Δ mutant were nearly normal, including endocytic transport to vacuoles, carboxypeptidase Y sorting, and the processing and secretion of invertase. In contrast, this mutant exhibited severe defects in the early endosome-to-TGN transport pathway; proteins that are transported via this pathway, such as the v-SNARE Snc1p, the t-SNARE Tlg1p, and the chitin synthase III subunit Chs3p, accumulated in TGN-independent aberrant membrane structures. We extended our analyses to clathrin adaptors, and found that Gga1p/Gga2p and AP-1 were also involved in this pathway. The Cdc50p-depleted gga1Δ gga2Δ mutant and the gcs1Δ apl2Δ (the β1 subunit of AP-1) mutant exhibited growth defects and intracellular Snc1p-containing membranes accumulated in these cells. These results suggest that Cdc50p-Drs2p plays an important role in the Arf1p-mediated formation of CCVs for the retrieval pathway from early endosomes to the TGN.