Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P20020 (adenosine triphosphatase)
 3,299 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Logarithmic cultures of Saccharomyces cerevisiae strains LBG H 1022, FL-100, X 2180 1A and 1B were studied together with the mutants pep4-3, sec18-1 and sec7-1. The necessary ultrastructural observations showed that, as a rule, juvenile vacuoles were formed de novo from perinuclear endoplasmic reticulum cisternae (ER) packed and inflated with electron-dense (polyanionic) matrix material. This process was disturbed solely in the sec18-1 mutant under non-permissive conditions. The vacuolar marker enzymes adenosine triphosphatase (ATPase) and alkaline phosphohydrolase (ALPase) were assayed by the ultracytochemical cerium precipitation technique. The neutral ATPase was active in vacuolar membranes and in the previously shown (coated) microglobules nearby. ALPase activity was detected in microglobules inside juvenile vacuoles, inside nucleus and in the cytoplasm as well as in the membrane vesicles and in the periplasm. The sites of vacuolar protease carboxypeptidase Y (CPY) activity were assayed using N-CBZ-L-tyrosine-4-methoxy-2-naphthyl-amide (CBZ-Tyr-MNA) as substrate and sites of the amino-peptidase M activity using Leu-MNA as substrate. Hexazotized p-rosaniline served as a coupler for the primary reaction product of both the above proteases (MNA) and the resulting azo-dye was osmicated during postfixation. The CPY reaction product was found in both polar layers of vacuolar membranes (homologous to ER) and in ER membranes enclosing condensed lipoprotein bodies which were taken up by the vacuoles of late logarithmic yeast. Both before and after the uptake into the vacuoles the bodies contained the CPY reaction product in concentric layers or in cavities. Microglobules with CPY activity were also observed. Aminopeptidase was localized in microglobules inside the juvenile vacuoles. These findings combined with the previous cytochemical localizations of polyphosphates and X-prolyl-dipeptidyl (amino)peptidase in S. cerevisiae suggest the following cytologic mechanism for the biosynthetic protein transport: coated microglobules convey metabolites and enzymes either to the cell surface for secretion or enter the vacuoles in all phases of the cell cycle. The membrane vesicles represent an alternative secretory mechanism present in yeast cells only during budding. The homology of the ER with the vacuolar membranes and with the surface membranes of the lipoprotein condensates (bodies) indicates a cotranslational entry of the CPY into these membranes. The secondary transfer of a portion of CPY into vacuoles is probably mediated by the lipoprotein uptake process.
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PMID:Ultracytochemical localization of the vacuolar marker enzymes alkaline phosphatase, adenosine triphosphatase, carboxypeptidase Y and aminopeptidase reveal new concept of vacuole biogenesis in Saccharomyces cerevisiae. 253 Nov 29

A study was made of the enzyme content of the isolated cell walls and of a plasma-membrane preparation obtained by centrifugation after enzymic digestion of the cell walls of baker's yeast. The isolated cell walls showed no hexokinase, alkaline phosphatase, esterase or NADH oxidase activity. It was concluded that these enzymes exist only in the interior of the cell. Further, only a negligible activity of deamidase was detectable in the cell walls. Noticeable amounts of saccharase, phosphatases hydrolysing p-nitrophenyl phosphate, ATP, ADP, thiamin pyrophosphate and PP(i), with optimum activity at pH3-4, and an activity of Mg(2+)-dependent adenosine triphosphatase at neutral pH, were found in the isolated cell walls. During enzymic digestion, the other activities appearing in the cell walls were mostly released into the medium, but the bulk of the Mg(2+)-dependent adenosine triphosphatase remained in the plasma-membrane preparation. Accordingly, it may be assumed that the enzymes released into the medium during digestion are located in the cell wall outside the plasma membrane, whereas the Mg(2+)-dependent adenosine triphosphatase is an enzyme of the plasma membrane. This enzyme differs from the phosphatases with pH optima in the range pH3-4 with regard to location, pH optimum, substrate specificity and different requirement of activators.
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PMID:The enzymic composition of the isolated cell wall and plasma membrane of baker's yeast. 431 24

The yeast Ca2+ adenosine triphosphatase Pmr1, located in medial-Golgi, has been implicated in intracellular transport of Ca2+ and Mn2+ ions. We show here that addition of Mn2+ greatly alleviates defects of pmr1 mutants in N-linked and O-linked protein glycosylation. In contrast, accurate sorting of carboxypeptidase Y (CpY) to the vacuole requires a sufficient supply of intralumenal Ca2+. Most remarkably, pmr1 mutants are also unable to degrade CpY*, a misfolded soluble endoplasmic reticulum protein, and display phenotypes similar to mutants defective in the stress response to malfolded endoplasmic reticulum proteins. Growth inhibition of pmr1 mutants on Ca2+-deficient media is overcome by expression of other Ca2+ pumps, including a SERCA-type Ca2+ adenosine triphosphatase from rabbit, or by Vps10, a sorting receptor guiding non-native luminal proteins to the vacuole. Our analysis corroborates the dual function of Pmr1 in Ca2+ and Mn2+ transport and establishes a novel role of this secretory pathway pump in endoplasmic reticulum-associated processes.
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PMID:The medial-Golgi ion pump Pmr1 supplies the yeast secretory pathway with Ca2+ and Mn2+ required for glycosylation, sorting, and endoplasmic reticulum-associated protein degradation. 957 Dec 46

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). Here, we show that SWA4 is allelic to CDC50, encoding a membrane protein previously shown to chaperone Drs2p from the endoplasmic reticulum to the Golgi complex. We find that cdc50Delta exhibits the same clathrin-deficient phenotypes as drs2Delta, including delayed transport of carboxypeptidase Y to the vacuole, mislocalization of resident TGN enzymes and the accumulation of aberrant membrane structures. These trafficking defects precede appearance of cell polarity defects in cdc50Delta, suggesting that the latter are a secondary consequence of disrupting Golgi function. Involvement of Drs2p-Cdc50p in PS translocation suggests a role in restricting PS to the cytosolic leaflet of the Golgi and plasma membrane. Annexin V binding and papuamide B hypersensitivity indicate that drs2Delta or cdc50Delta causes a loss of plasma membrane PS asymmetry. However, clathrin and other endocytosis null mutants also exhibit a comparable loss of PS asymmetry, and studies with drs2-ts and clathrin (chc1-ts) conditional mutants suggest that loss of plasma membrane asymmetry is a secondary consequence of disrupting protein trafficking.
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PMID:Roles for the Drs2p-Cdc50p complex in protein transport and phosphatidylserine asymmetry of the yeast plasma membrane. 1695 84