scholarly journals Quality control of a mutant plasma membrane ATPase: ubiquitylation prevents cell-surface stability

2006 ◽  
Vol 119 (2) ◽  
pp. 360-369 ◽  
Author(s):  
Y. Liu
Keyword(s):  
Quality Control ◽  
Plasma Membrane ◽  
Cell Surface ◽  
Plasma Membrane Atpase ◽  
Surface Stability ◽  
Membrane Atpase

scholarly journals An Endosome-to-Plasma Membrane Pathway Involved in Trafficking of a Mutant Plasma Membrane ATPase in Yeast

2000 ◽  
Vol 11 (2) ◽  
pp. 579-592 ◽  
Author(s):  
Wen-jie Luo ◽  
Amy Chang
Keyword(s):  
Plasma Membrane ◽  
Cell Surface ◽  
Secretory Pathway ◽  
Protein Sorting ◽  
Temperature Sensitive ◽  
Plasma Membrane Atpase ◽  
Vacuolar Protein Sorting ◽  
Membrane Atpase ◽  
Vacuolar Protein ◽  
Endosomal System

The plasma membrane ATPase, encoded by PMA1, is delivered to the cell surface via the secretory pathway. Previously, we characterized a temperature-sensitive pma1 mutant in which newly synthesized Pma1-7 is not delivered to the plasma membrane but is mislocalized instead to the vacuole at 37°C. Severalvps mutants, which are defective in vacuolar protein sorting, suppress targeting-defective pma1 by allowing mutant Pma1 to move once again to the plasma membrane. In this study, we have analyzed trafficking in the endosomal system by monitoring the movement of Pma1-7 in vps36, vps1, andvps8 mutants. Upon induction of expression, mutant Pma1 accumulates in the prevacuolar compartment in vps36cells. After chase, a fraction of newly synthesized Pma1-7 is delivered to the plasma membrane. In both vps1 andvps8 cells, newly synthesized mutant Pma1 appears in small punctate structures before arrival at the cell surface. Nevertheless, biosynthetic membrane traffic appears to follow different routes in vps8 and vps1: the vacuolar protein-sorting receptor Vps10p is stable in vps8 but not in vps1. Furthermore, a defect in endocytic delivery to the vacuole was revealed in vps8 (andvps36) but not vps1 by endocytosis of the bulk membrane marker FM 4-64. Moreover, in vps8 cells, there is defective down-regulation from the cell surface of the mating receptor Ste3, consistent with persistent receptor recycling from an endosomal compartment to the plasma membrane. These data support a model in which mutant Pma1 is diverted from the Golgi to the surface invps1 cells. We hypothesize that in vps8and vps36, in contrast to vps1, mutant Pma1 moves to the surface via endosomal intermediates, implicating an endosome-to-surface traffic pathway.

scholarly journals Ubiquitin-mediated Targeting of a Mutant Plasma Membrane ATPase, Pma1-7, to the Endosomal/Vacuolar System in Yeast

2004 ◽  
Vol 15 (5) ◽  
pp. 2401-2409 ◽  
Author(s):  
Maddalena Pizzirusso ◽  
Amy Chang
Keyword(s):  
Plasma Membrane ◽  
Cell Surface ◽  
Ubiquitin Ligase ◽  
Secretory Pathway ◽  
Protein Transport ◽  
Plasma Membrane Atpase ◽  
Membrane Atpase ◽  
Endosomal Pathway ◽  
Quality Control Mechanism ◽  
Vacuolar System

Pma1-7 is a mutant plasma membrane ATPase that is impaired in targeting to the cell surface at 37°C and is delivered instead to the endosomal/vacuolar pathway for degradation. We have proposed that Pma1-7 is a substrate for a Golgibased quality control mechanism. By contrast with wild-type Pma1, Pma1-7 is ubiquitinated. Ubiquitination and endosomal targeting of Pma1-7 is dependent on the Rsp5-Bul1-Bul2 ubiquitin ligase protein complex but not the transmembrane ubiquitin ligase Tul1. Analysis of Pma1-7 ubiquitination in mutants blocked in protein transport at various steps of the secretory pathway suggests that ubiquitination occurs after ER exit but before endosomal entry. In the absence of ubiquitination in rsp5-1 cells, Pma1-7 is delivered to the cell surface and remains stable. Nevertheless, Pma1-7 remains impaired in association with detergent-insoluble glycolipid-enriched complexes in rsp5-1 cells, suggesting that ubiquitination is not the cause of Pma1-7 exclusion from rafts. In vps1 cells in which protein transport into the endosomal pathway is blocked, Pma1-7 is routed to the cell surface. On arrival at the plasma membrane in vps1 cells, Pma1-7 remains stable and its ubiquitination disappears, suggesting deubiquitination activity at the cell surface. We suggest that Pma1-7 sorting and fate are regulated by ubiquitination.

Reconstitution of proton pumping activity of a plasma membrane ATPase purified from radish

1985 ◽  
Vol 37 (3) ◽  
pp. 189-193 ◽  
Author(s):  
Maria Cecilia Cocucci ◽  
Maria Ida De Michelis ◽  
Maria Chiara Pugliarello ◽  
Franca Rasi-Caldogno
Keyword(s):  
Plasma Membrane ◽  
Proton Pumping ◽  
Plasma Membrane Atpase ◽  
Membrane Atpase ◽  
Pumping Activity
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