High impact information on DRS2

• Recent studies describe a requirement for the yeast Drs2p family of P-type ATPases in both phospholipid translocation and protein transport in the secretory and endocytic pathways [1].
• The drs2 null allele is also synthetically lethal with clathrin heavy chain (chc1) temperature-sensitive alleles, but not with mutations in COPI subunits or other SEC genes tested [2].
• Subcellular fractionation and immunofluorescence analysis indicate that Drs2p localizes to late Golgi membranes containing Kex2p [2].
• The deduced amino acid sequence of ALA1 is homologous with those of yeast DRS2 and bovine ATPase II, both of which are putative aminophospholipid translocases [3].
• However, cho1 yeast strains that are unable to synthesize PS do not phenocopy drs2 but instead transport proteins normally via the secretory pathway [4].

Biological context of DRS2

• NEO1 is the only essential gene in APT family and seems to be functionally distinct from the DRS2/DNF genes [5].
• The specificity of Drs2p for NBD-PS suggested that translocation of PS would be required for the function of Drs2p in protein transport from the TGN [4].
• The predicted amino acid sequence encoded by DRS2 contains seven transmembrane domains, a phosphate-binding loop found in ATP- or GTP-binding proteins, and a seven-amino-acid sequence detected in all classes of P-type ATPases [6].
• Deletion and mutational analysis identified two downstream activation sites (DAS1 and DAS2) and two downstream repressor sites (DRS1 and DRS2) that influence the rate of LPD1 transcription rather than mRNA degradation or translation [7].
• The cold-sensitive phenotype of drs2 is suppressed by extra copies of the TEF3 gene, which encodes a yeast homolog of eukaryotic translation elongation factor EF-1 gamma [6].

Anatomical context of DRS2

• Drs2p from budding yeast localizes to the trans-Golgi network (TGN), and here we show that this membrane contains an ATP-dependent APLT that flips 7-nitro-2-1,3-benzoxadiazol-4-yl (NBD) PS and PE derivatives from the luminal to the cytosolic leaflet [4].
• We find that Drs2p is required to form a specific class of secretory vesicles that accumulate when the actin cytoskeleton is disrupted [8].
• An essential subfamily of Drs2p-related P-type ATPases is required for protein trafficking between Golgi complex and endosomal/vacuolar system [5].
• Drs2p-dependent formation of exocytic clathrin-coated vesicles in vivo [8].
• The yeast DRS2 gene, which is required for growth at 23 degreesC or below, encodes a member of a P-type ATPase subgroup reported to transport aminophospholipids between the leaflets of the plasma membrane [9].

Associations of DRS2 with chemical compounds

• The neomycin-resistance 1 gene (NEO1) encodes a potential 1151 as integral membrane protein, most homologous to the yeast DRS2 gene product, a Ca(2+)-ATPase involved in cytoplasmic ribosome assembly [10].
• Gel mobility shift analysis and in vitro DNase I footprinting have shown that proteins bind specifically to two downstream repressor sequences (DRS1 located from +140 to +163 and DRS2 located between +231 and +251) that influence the rate of HXK2 transcription when ethanol is used as carbon source by Saccharomyces cerevisiae [11].
• Furthermore, the absence of Drs2p had no effect on the amount of endogenous PE exposed to the outer leaflet of the plasma membrane as detected by labeling with trinitrobenzene sulfonic acid [9].
• Defects in structural integrity of ergosterol and the Cdc50p-Drs2p putative phospholipid translocase cause accumulation of endocytic membranes, onto which actin patches are assembled in yeast [12].
• Drs2p, a P-type adenosine triphosphatase required for a phosphatidylserine (PS) flippase activity in the yeast trans Golgi network (TGN), was first implicated in protein trafficking by a screen for mutations synthetically lethal with arf1 (swa) [13].

Physical interactions of DRS2

• Cdc50p was coimmunoprecipitated with Drs2p from membrane protein extracts [14].
• We have previously implicated Drs2p in protein transport steps in the late secretory pathway requiring ADP-ribosylation factor (ARF) and clathrin [15].
• Here we show that Drs2p interacts directly with Gea2p, both in vitro and in vivo [16].

Other interactions of DRS2

• Genetic studies suggest that CDC50 performs a function similar to DRS2, which encodes a P-type ATPase of the aminophospholipid translocase (APT) subfamily [14].
• Moreover, SVs have an asymmetric PE arrangement that is lost upon removal of Drs2p and Dnf3p [17].
• Unlike TEF3, extra copies of TEF4 do not suppress the cold-sensitive 40S ribosomal subunit deficiency of a drs2 strain [18].
• DRS1 requires the concerted action of DRS2 (a RAP1 motif at position +406) for repression of transcription only when the gene is induced [7].
• Yeast P4-ATPases Drs2p and Dnf1p Are Essential Cargos of the NPFXD/Sla1p Endocytic Pathway [19].

Analytical, diagnostic and therapeutic context of DRS2

• Quantification of the amount of cell-associated NBD fluorescence using flow cytometry indicated a significant decrease in the absence of Drs2p, but this decrease was not restricted to the aminophospholipids (phosphatidylserine and phosphatidylethanolamine) and was dependent on culture conditions [9].

References