scholarly journals PtdIns4P synthesis by PI4KIIIα at the plasma membrane and its impact on plasma membrane identity

2012 ◽  
Vol 199 (6) ◽  
pp. 1003-1016 ◽  
Author(s):  
Fubito Nakatsu ◽  
Jeremy M. Baskin ◽  
Jeeyun Chung ◽  
Lukas B. Tanner ◽  
Guanghou Shui ◽  
...  
Keyword(s):  
Plasma Membrane ◽  
Membrane Protein ◽  
Membrane Localization ◽  
Plasma Membrane Localization ◽  
Metabolic Conversion ◽  
Evolutionarily Conserved ◽  
Peripheral Membrane Protein ◽  
Higher Eukaryotes ◽  
Definition Of ◽  
Modest Reduction

Plasma membrane phosphatidylinositol (PI) 4-phosphate (PtdIns4P) has critical functions via both direct interactions and metabolic conversion to PI 4,5-bisphosphate (PtdIns(4,5)P2) and other downstream metabolites. However, mechanisms that control this PtdIns4P pool in cells of higher eukaryotes remain elusive. PI4KIIIα, the enzyme thought to synthesize this PtdIns4P pool, is reported to localize in the ER, contrary to the plasma membrane localization of its yeast homologue, Stt4. In this paper, we show that PI4KIIIα was targeted to the plasma membrane as part of an evolutionarily conserved complex containing Efr3/rolling blackout, which we found was a palmitoylated peripheral membrane protein. PI4KIIIα knockout cells exhibited a profound reduction of plasma membrane PtdIns4P but surprisingly only a modest reduction of PtdIns(4,5)P2 because of robust up-regulation of PtdIns4P 5-kinases. In these cells, however, much of the PtdIns(4,5)P2 was localized intracellularly, rather than at the plasma membrane as in control cells, along with proteins typically restricted to this membrane, revealing a major contribution of PI4KIIIα to the definition of plasma membrane identity.

scholarly journals Erf4p and Erf2p Form an Endoplasmic Reticulum-associated Complex Involved in the Plasma Membrane Localization of Yeast Ras Proteins

2002 ◽  
Vol 277 (51) ◽  
pp. 49352-49359 ◽  
Author(s):  
Lihong Zhao ◽  
Sandra Lobo ◽  
Xiangwen Dong ◽  
Addison D. Ault ◽  
Robert J. Deschenes
Keyword(s):  
Endoplasmic Reticulum ◽  
Plasma Membrane ◽  
Membrane Protein ◽  
Secretory Pathway ◽  
Integral Membrane Protein ◽  
Genetic Screen ◽  
Membrane Localization ◽  
Ras Proteins ◽  
Transport Pathway ◽  
Plasma Membrane Localization

Ras oncogene proteins are plasma membrane-associated signal transducers that are found in all eukaryotes. Posttranslational addition of lipid to a carboxyl-terminal CaaXbox (where “C” represents a cysteine, “a” is generally an aliphatic residue, andXcan be any amino acid) is required to target Ras proteins to the cytosolic surface of the plasma membrane. The pathway by which Ras translocates from the endoplasmic reticulum to the plasma membrane is currently not clear. We have performed a genetic screen to identify components of the Ras plasma membrane localization pathway. Mutations in two genes,ERF2andERF4/SHR5, have been shown to affect the palmitoylation and subcellular localization of Ras proteins. In this report, we show that Erf4p is localized on the endoplasmic reticulum as a peripheral membrane protein in a complex with Erf2p, an integral membrane protein that was identified from the same genetic screen. Erf2p has been shown to be required for the plasma membrane localization of GFP-Ras2p via a pathway distinct from the classical secretory pathway (X. Dong and R. J. Deschenes, manuscript in preparation). We show here that Erf4p, like Erf2p, is involved in the plasma membrane localization of Ras2p. Erf2p and Erf4p represent components of a previously uncharacterized subcellular transport pathway involved in the plasma membrane targeting of Ras proteins.

scholarly journals Lipid binding by the N-terminal motif mediates plasma membrane localization of Bordetella effector protein BteA

2021 ◽  
pp. 100607
Author(s):  
Ivana Malcova ◽  
Ladislav Bumba ◽  
Filip Uljanic ◽  
Darya Kuzmenko ◽  
Jana Nedomova ◽  
...  
Keyword(s):  
Plasma Membrane ◽  
Lipid Binding ◽  
Membrane Localization ◽  
Effector Protein ◽  
Plasma Membrane Localization

scholarly journals Palmitoylation of Sindbis Virus TF Protein Regulates Its Plasma Membrane Localization and Subsequent Incorporation into Virions

2016 ◽  
Vol 91 (3) ◽  
Author(s):  
Jolene Ramsey ◽  
Emily C. Renzi ◽  
Randy J. Arnold ◽  
Jonathan C. Trinidad ◽  
Suchetana Mukhopadhyay
Keyword(s):  
Plasma Membrane ◽  
Sindbis Virus ◽  
Molecular Mechanisms ◽  
Wild Type Virus ◽  
Membrane Localization ◽  
Clear Understanding ◽  
Wild Type ◽  
Plasma Membrane Localization ◽  
C Terminus ◽  
N Terminus

ABSTRACT Palmitoylation is a reversible, posttranslational modification that helps target proteins to cellular membranes. The alphavirus small membrane proteins 6K and TF have been reported to be palmitoylated and to positively regulate budding. 6K and TF are isoforms that are identical in their N termini but unique in their C termini due to a −1 ribosomal frameshift during translation. In this study, we used cysteine (Cys) mutants to test differential palmitoylation of the Sindbis virus 6K and TF proteins. We modularly mutated the five Cys residues in the identical N termini of 6K and TF, the four additional Cys residues in TF's unique C terminus, or all nine Cys residues in TF. Using these mutants, we determined that TF palmitoylation occurs primarily in the N terminus. In contrast, 6K is not palmitoylated, even on these shared residues. In the C-terminal Cys mutant, TF protein levels increase both in the cell and in the released virion compared to the wild type. In viruses with the N-terminal Cys residues mutated, TF is much less efficiently localized to the plasma membrane, and it is not incorporated into the virion. The three Cys mutants have minor defects in cell culture growth but a high incidence of abnormal particle morphologies compared to the wild-type virus as determined by transmission electron microscopy. We propose a model where the C terminus of TF modulates the palmitoylation of TF at the N terminus, and palmitoylated TF is preferentially trafficked to the plasma membrane for virus budding. IMPORTANCE Alphaviruses are a reemerging viral cause of arthritogenic disease. Recently, the small 6K and TF proteins of alphaviruses were shown to contribute to virulence in vivo. Nevertheless, a clear understanding of the molecular mechanisms by which either protein acts to promote virus infection is missing. The TF protein is a component of budded virions, and optimal levels of TF correlate positively with wild-type-like particle morphology. In this study, we show that the palmitoylation of TF regulates its localization to the plasma membrane, which is the site of alphavirus budding. Mutants in which TF is not palmitoylated display drastically reduced plasma membrane localization, which effectively prevents TF from participating in budding or being incorporated into virus particles. Investigation of the regulation of TF will aid current efforts in the alphavirus field searching for approaches to mitigate alphaviral disease in humans.

scholarly journals A novel RCE1 isoform is required for H-Ras plasma membrane localization and is regulated by USP17

2013 ◽  
Vol 457 (2) ◽  
pp. 289-300 ◽  
Author(s):  
Jakub Jaworski ◽  
Ureshnie Govender ◽  
Cheryl McFarlane ◽  
Michelle de la Vega ◽  
Michelle K. Greene ◽  
...  
Keyword(s):  
Plasma Membrane ◽  
Membrane Localization ◽  
Plasma Membrane Localization

We have identified a novel RCE1 isoform which is required for proper H-Ras processing and plasma membrane localization. In addition, we have shown that USP17 can regulate this novel isoform and thus RCE1 activity by deubiquitinating Lys43.

scholarly journals Role of Ezrin/Radixin/Moesin in the Surface Localization of Programmed Cell Death Ligand-1 in Human Colon Adenocarcinoma LS180 Cells

2021 ◽  
Vol 14 (9) ◽  
pp. 864
Author(s):  
Takuro Kobori ◽  
Chihiro Tanaka ◽  
Mayuka Tameishi ◽  
Yoko Urashima ◽  
Takuya Ito ◽  
...  
Keyword(s):  
Cell Death ◽  
Plasma Membrane ◽  
Programmed Cell Death ◽  
Cell Surface ◽  
Actin Cytoskeleton ◽  
Mrna Level ◽  
Scaffold Proteins ◽  
Membrane Localization ◽  
Erm Proteins ◽  
Plasma Membrane Localization

Programmed cell death ligand-1 (PD-L1), an immune checkpoint protein highly expressed on the cell surface in various cancer cell types, binds to programmed cell death-1 (PD-1), leading to T-cell dysfunction and tumor survival. Despite clinical successes of PD-1/PD-L1 blockade therapies, patients with colorectal cancer (CRC) receive little benefit because most cases respond poorly. Because high PD-L1 expression is associated with immune evasion and poor prognosis in CRC patients, identifying potential modulators for the plasma membrane localization of PD-L1 may represent a novel therapeutic strategy for enhancing the efficacy of PD-1/PD-L1 blockade therapies. Here, we investigated whether PD-L1 expression in human colorectal adenocarcinoma cells (LS180) is affected by ezrin/radixin/moesin (ERM), functioning as scaffold proteins that crosslink plasma membrane proteins with the actin cytoskeleton. We observed colocalization of PD-L1 with all three ERM proteins in the plasma membrane and detected interactions involving PD-L1, the three ERM proteins, and the actin cytoskeleton. Furthermore, gene silencing of ezrin and radixin, but not of moesin, substantially decreased the expression of PD-L1 on the cell surface without affecting its mRNA level. Thus, in LS180 cells, ezrin and radixin may function as scaffold proteins mediating the plasma membrane localization of PD-L1, possibly by post-translational modification.

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