Characterization of the plasma membrane ATPase of Saccharomyces cerevisiae

1978 ◽  
Vol 22 (1) ◽  
Author(s):  
Ram�n Serrano
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Plasma Membrane ◽  
Plasma Membrane Atpase ◽  
Membrane Atpase

scholarly journals Secretory vesicles externalize the major plasma membrane ATPase in yeast.

1988 ◽  
Vol 106 (3) ◽  
pp. 641-648 ◽  
Author(s):  
C L Holcomb ◽  
W J Hansen ◽  
T Etcheverry ◽  
R Schekman
Keyword(s):  
Plasma Membrane ◽  
Secretory Pathway ◽  
Biochemical Characterization ◽  
Plasma Membrane Atpase ◽  
Membrane Assembly ◽  
Yeast Cell Surface ◽  
Membrane Atpase ◽  
Constitutive Secretion ◽  
Secretory Enzyme

Yeast cell surface growth is accomplished by constitutive secretion and plasma membrane assembly, culminating in the fusion of vesicles with the bud membrane. Coordination of secretion and membrane assembly has been investigated by examining the biogenesis of plasma membrane ATPase (PM ATPase) in secretion-defective (sec) strains of Saccharomyces cerevisiae. PM ATPase is synthesized as a approximately 106-kD polypeptide that is not detectably modified by asparagine-linked glycosylation or proteolysis during transit to the plasma membrane. Export of the PM ATPase requires the secretory pathway. In sec1, a mutant defective in the last step of secretion, large amounts of Golgi-derived vesicles are accumulated. Biochemical characterization of this organelle has demonstrated that PM ATPase and the secretory enzyme, acid phosphatase, are transported in a single vesicle species.

Pleiotropic plasma membrane ATPase mutations of Saccharomyces cerevisiae

1987 ◽  
Vol 7 (11) ◽  
pp. 4082-4088
Author(s):  
J H McCusker ◽  
D S Perlin ◽  
J E Haber
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Plasma Membrane ◽  
Synthetic Medium ◽  
Aminoglycoside Antibiotic ◽  
Weak Acid ◽  
Plasma Membrane Atpase ◽  
Pressure Sensitive ◽  
Intragenic Complementation ◽  
Membrane Atpase ◽  
Internal Ph

We isolated a large number of mutations in the structural gene for the plasma membrane ATPase (PMA1) of Saccharomyces cerevisiae. These mutations were selected by their resistance to the aminoglycoside antibiotic hygromycin B. Biochemical analysis of purified membrane preparations showed that the plasma membrane ATPase activity of the mutants was reduced as much as 75%. Intragenic complementation of pma1 mutants suggested that the yeast plasma membrane ATPase was a multimeric enzyme. The pma1 mutants were apparently defective in maintaining internal pH; more than half of the mutants were unable to grow either at a low pH or in the presence of a weak acid. Most pma1 mutants were also osmotic pressure sensitive. At a very low temperature (5 degrees C) many pma1 mutants were unable to grow and were arrested as unbudded cells. The three most severely affected mutants were also unable to grow in the presence of NH4+. The most extreme mutant exhibited a severe defect in progression through the cell cycle; on synthetic medium, the cells progressively accumulated nucleus-containing small buds that generally failed to complete bud enlargement and cytokinesis. Most of the pleiotropic phenotypes of pma1 mutants could be suppressed by the addition of 50 mM KCl but not NaCl to the medium.

scholarly journals Metabolic instability and constitutive endocytosis of STE6, the a-factor transporter of Saccharomyces cerevisiae.

1994 ◽  
Vol 5 (11) ◽  
pp. 1185-1198 ◽  
Author(s):  
C Berkower ◽  
D Loayza ◽  
S Michaelis
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Plasma Membrane ◽  
Sufficient Information ◽  
Plasma Membrane Atpase ◽  
Amino Acid Permease ◽  
Membrane Atpase ◽  
A Cell ◽  
Pattern Characteristic ◽  
General Amino Acid Permease ◽  
Punctate Pattern

STE6, a member of the ATP binding cassette (ABC) transporter superfamily, is a membrane protein required for the export of the a-factor mating pheromone in Saccharomyces cerevisiae. To initiate a study of the intracellular trafficking of STE6, we have examined its half-life and localization. We report here that STE6 is metabolically unstable in a wild-type strain, and that this instability is blocked in a pep4 mutant, suggesting that degradation of STE6 occurs in the vacuole and is dependent upon vacuolar proteases. In agreement with a model whereby STE6 is routed to the vacuole via endocytosis from the plasma membrane, we show that degradation of STE6 is substantially reduced at nonpermissive temperature in mutants defective in delivery of proteins to the plasma membrane (sec6) or in endocytosis (end3 and end4). Whereas STE6 appears to undergo constitutive internalization from the plasma membrane, as do the pheromone receptors STE2 and STE3, we show that two other proteins, the plasma membrane ATPase (PMA1) and the general amino acid permease (GAP1), are significantly more stable than STE6, indicating that rapid turnover in the vacuole is not a fate common to all plasma membrane proteins in yeast. Investigation of STE6 partial molecules (half- and quarter-molecules) indicates that both halves of STE6 contain sufficient information to mediate internalization. Examination of STE6 localization by indirect immunofluorescence indicates that STE6 is found in a punctate, possibly vesicular, intracellular pattern, distinct from the rim-staining pattern characteristic of PMA1. The punctate pattern is consistent with the view that most of the STE6 molecules present in a cell at any given moment could be en route either to or from the plasma membrane. In a pep4 mutant, STE6 is concentrated in the vacuole, providing further evidence that the vacuole is the site of STE6 degradation, while in an end4 mutant STE6 exhibits rim-staining, indicating that it can accumulate in the plasma membrane when internalization is blocked. Taken together, the results presented here suggest that STE6 first travels to the plasma membrane and subsequently undergoes endocytosis and degradation in the vacuole, with perhaps only a transient residence at the plasma membrane; an alternative model, in which STE6 circumvents the plasma membrane, is also discussed.

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