scholarly journals Genetic variants help define the role of the MC4R C-terminus in signaling and cell surface stability

2018 ◽  
Vol 8 (1) ◽  
Author(s):  
Bryn S. Moore ◽  
Tooraj Mirshahi
Keyword(s):  
Cell Surface ◽  
Genetic Variants ◽  
Surface Stability ◽  
C Terminus

scholarly journals FAP-1 Association with Fas (Apo-1) Inhibits Fas Expression on the Cell Surface

2003 ◽  
Vol 23 (10) ◽  
pp. 3623-3635 ◽  
Author(s):  
Vladimir N. Ivanov ◽  
Pablo Lopez Bergami ◽  
Gabriel Maulit ◽  
Taka-Aki Sato ◽  
David Sassoon ◽  
...  
Keyword(s):  
Cell Surface ◽  
Fas Ligand ◽  
Surface Expression ◽  
Dominant Negative ◽  
Intracellular Pool ◽  
C Terminus ◽  
Interfering Rna ◽  
Insight Into ◽  
Advanced Tumors

ABSTRACT As revealed by intracellular pools of nonactive Fas (Apo-1), export of Fas to the cell surface is often impaired in human tumors, thereby inactivating Fas ligand-mediated apoptosis. Here, we demonstrate that association with Fas-associated phosphatase 1 (FAP-1) attenuates Fas export to the cell surface. Forced expression of FAP-1 reduces cell surface Fas levels and increases the intracellular pool of Fas within the cytoskeleton network. Conversely, expression of dominant-negative forms of FAP-1, or inhibition of FAP-1 expression by short interfering RNA, efficiently up-regulates surface expression of Fas. Inhibition of Fas surface expression by FAP-1 depends on its association with the C terminus of Fas. Mutation within amino acid 275 results in decreased association with FAP-1 and greater export of Fas to the cell surface in melanomas, normal fibroblasts, or Fas null cells. Identifying the role of FAP-1 in binding to, and consequently inhibition of, Fas export to the cell surface provides novel insight into the mechanism underlying the regulation of Fas trafficking, which is commonly impaired in advanced tumors with FAP-1 overexpression.

scholarly journals Function of AtPGAP1 in GPI anchor lipid remodeling and transport to the cell surface of GPI-anchored proteins

2021 ◽  
Author(s):  
César Bernat-Silvestre ◽  
Judit Sanchez-Simarro ◽  
Yingxuan Ma ◽  
Kim Johnson ◽  
Fernando Aniento ◽  
...  
Keyword(s):  
Cell Surface ◽  
Acyl Chain ◽  
Growth Stress ◽  
Loss Of Function ◽  
Gpi Anchor ◽  
C Terminus ◽  
Gpi Transamidase ◽  
Er Export ◽  
Inositol Ring

ABSTRACTGPI-anchored proteins (GPI-APs) play an important role in a variety of plant biological processes including growth, stress response, morphogenesis, signalling and cell wall biosynthesis. The GPI-anchor contains a lipid-linked glycan backbone that is synthesized in the endoplasmic reticulum (ER) where it is subsequently transferred to the C-terminus of proteins containing a GPI signal peptide by a GPI transamidase. Once the GPI anchor is attached to the protein, the glycan and lipid moieties are remodelled. In mammals and yeast, this remodelling is required for GPI-APs to be included in Coat Protein II (COPII) coated vesicles for their ER export and subsequent transport to the cell surface. The first reaction of lipid remodelling is the removal of the acyl chain from the inositol group by Bst1p (yeast) and PGAP1 (mammals). In this work, we have used a loss-of-function approach to study the role of PGAP1/Bst1 like genes in plants. We have found that Arabidopsis PGAP1 localizes to the ER and probably functions as the GPI inositol-deacylase which cleaves the acyl chain from the inositol ring of the GPI anchor. In addition, we show that PGAP1 function is required for efficient ER export and transport to the cell surface of GPI-APs.One sentence summaryGPI anchor lipid remodeling in GPI-anchored proteins is required for their transport to the cell surface in Arabidopsis.

scholarly journals Structural determinants regulating cell surface targeting of melanocortin receptors

2013 ◽  
Vol 51 (2) ◽  
pp. R23-R32 ◽  
Author(s):  
A R Rodrigues ◽  
D Sousa ◽  
H Almeida ◽  
A M Gouveia
Keyword(s):  
Cell Surface ◽  
Surface Expression ◽  
Cell Surface Expression ◽  
Melanocortin Receptors ◽  
Control Mechanisms ◽  
Structural Determinants ◽  
Surface Integration ◽  
C Terminus ◽  
G Protein Coupled

Melanocortin receptors (MCRs) belong to the G-protein-coupled receptor family of transmembrane proteins. They recognize specific ligands named melanocortins that are mainly produced in the pituitary and hypothalamus. Newly synthesized MCRs at the endoplasmic reticulum are subjected to quality control mechanisms that screen for the correct structure, folding or processing, essential for their proper cell surface expression. Some motifs, located at the N- or C-terminus or even on transmembrane and in loop regions, have been implicated in these biological processes. This article reviews these specific domains and the role of accessory proteins and post-translation modifications in MCRs' targeting to cell surface. Additionally, promising approaches involving pharmacological stabilization of misfolded and misrouted mutant MCRs, which improve their forward transport, are reported. Understanding the MCRs' structural determinants fundamental for their proper cell surface integration is essential for correcting abnormalities found in some diseases.

Role of C-terminus of Kir7.1 potassium channel in cell-surface expression

2006 ◽  
Vol 30 (3) ◽  
pp. 270-277 ◽  
Author(s):  
Toru Tateno ◽  
Nobuhiro Nakamura ◽  
Yukio Hirata ◽  
Shigehisa Hirose
Keyword(s):  
Cell Surface ◽  
Potassium Channel ◽  
Surface Expression ◽  
Cell Surface Expression ◽  
C Terminus

scholarly journals Gis4, a New Component of the Ion Homeostasis System in the Yeast Saccharomyces cerevisiae

2006 ◽  
Vol 5 (10) ◽  
pp. 1611-1621 ◽  
Author(s):  
Tian Ye ◽  
Raúl García-Salcedo ◽  
José Ramos ◽  
Stefan Hohmann
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Salt Tolerance ◽  
Cell Surface ◽  
Ion Homeostasis ◽  
Yeast Saccharomyces Cerevisiae ◽  
Snf1 Kinase ◽  
C Terminus ◽  
Surface Localization ◽  
As Stress

ABSTRACT Gis4 is a new component of the system required for acquisition of salt tolerance in Saccharomyces cerevisiae. The gis4Δ mutant is sensitive to Na+ and Li+ ions but not to osmotic stress. Genetic evidence suggests that Gis4 mediates its function in salt tolerance, at least partly, together with the Snf1 protein kinase and in parallel with the calcineurin protein phosphatase. When exposed to salt stress, mutants lacking gis4Δ display a defect in maintaining low intracellular levels of Na+ and Li+ ions and exporting those ions from the cell. This defect is due to diminished expression of the ENA1 gene, which encodes the Na+ and Li+ export pump. The protein sequence of Gis4 is poorly conserved and does not reveal any hints to its molecular function. Gis4 is enriched at the cell surface, probably due to C-terminal farnesylation. The CAAX box at the C terminus is required for cell surface localization but does not seem to be strictly essential for the function of Gis4 in salt tolerance. Gis4 and Snf1 seem to share functions in the control of ion homeostasis and ENA1 expression but not in glucose derepression, the best known role of Snf1. Together with additional evidence that links Gis4 genetically and physically to Snf1, it appears that Gis4 may function in a pathway in which Snf1 plays a specific role in controlling ion homeostasis. Hence, it appears that the conserved Snf1 kinase plays roles in different pathways controlling nutrient as well as stress response.

scholarly journals Role of C-Terminal Domains in Surface Attachment of the Fructosyltransferase of Streptococcus salivariusATCC 25975

1998 ◽  
Vol 180 (23) ◽  
pp. 6400-6403 ◽  
Author(s):  
Catherine Rathsam ◽  
Nicholas A. Jacques
Keyword(s):  
Cell Wall ◽  
Cell Surface ◽  
Streptococcus Salivarius ◽  
Surface Attachment ◽  
C Terminus ◽  
Anchoring Motif ◽  
Terminal Domains

ABSTRACT The cell-associated β-d-fructosyltransferase ofStreptococcus salivarius, which is devoid of the cell wall anchoring motif, LPXTG, is released on exposure to its substrate, sucrose. Deletions within the C terminus of the enzyme implicated both the hydrophobic and the proline-glycine-serine-threonine-rich wall-associated domain in stabilizing the enzyme on the cell surface.

Mutational analysis of the C-terminal anchoring domains ofStreptococcus mutansP1 antigen: Role of the LPXTGX motif in P1 association with the cell wall

2000 ◽  
Vol 46 (6) ◽  
pp. 584-592 ◽  
Author(s):  
Song F Lee ◽  
Lingqiu Gao
Keyword(s):  
Cell Wall ◽  
Cell Surface ◽  
Streptococcus Mutans ◽  
Mutational Analysis ◽  
Decisive Role ◽  
Site Directed Mutagenesis ◽  
Wild Type ◽  
Hydrophobic Domain ◽  
C Terminus

The salivary agglutinin-interacting adhesin P1 of Streptococcus mutans is anchored to the cell wall via the carboxy (C) terminus, which contains a wall-associated domain, a conserved LPXTGX motif, a hydrophobic domain, and a charged tail. To further investigate the role of the C-terminal anchoring regions in cell wall sorting and anchoring, mutational analysis was performed on P1 in this study. Three truncated P1 mutants and seven site-directed mutants were generated by a polymerase chain reaction-based technique. The mutated P1 genes were returned to the P1-negative S. mutans SM3352 for expression and localization studies by ELISA and Western immunoblotting. The results showed that P1 mutants with deletion of the hydrophobic domain and charged tail, or deletion of the charged tail alone resulted in the secretion of P1 to the culture medium. Results from cellular fractionation experiments with the truncated mutants showed that P1 was not trapped in the membrane or cytoplasm. The site-directed mutants showed normal distribution of P1 to the cell surface as compared to the wild-type. However, when cell walls prepared from the site-directed mutants were boiled with SDS, P1 could be removed readily from the mutants with Thr residue in the LPNTGV motif, altered to either Ser (T1531S) or Phe (T1531F); the mutant with Thr and Gly residues altered to two Phe residues (TG1531-1532FF), and the LPNTGV-deleted mutant (LPNTGV-). In contrast, the wild-type P1 and the other three site-directed P1 mutants (P1529V, N1530I, and G1532F) could not be removed by boiling SDS. When the cell wall P1s from the wild-type, mutants P1529V, N1530I, and G1532F were reacted with an antibody directed against the hydrophobic domain and charged tail, no reaction was detected. However, P1s from mutants T1531S, T1531F, TG1531-1532FF, and LPNTGV-were recognized by the antibody, indicating that the inability of these mutated P1s to firmly link to the cell wall was the result of failure in proteolytic cleavage of the hydrophobic domain and charged tail. In summary, the results suggest that the charged tail plays a decisive role in sorting P1 to the cell surface, while the LPXTGX motif determines the nature of P1-cell wall association. The Thr residue of the LPXTGX motif is required for enzymatic processing to link P1 to the cell wall, presumably via a covalent bond.Key words: antigen P1, cell wall proteins, Streptococcus mutans, protein anchoring, site-directed mutagenesis.

Trafficking and cell surface stability of ENaC

2001 ◽  
Vol 281 (3) ◽  
pp. F391-F399 ◽  
Author(s):  
Daniela Rotin ◽  
Voula Kanelis ◽  
Laurent Schild
Keyword(s):  
Cell Surface ◽  
Distal Colon ◽  
Type I ◽  
Surface Stability ◽  
Liddle’S Syndrome ◽  
Nonionic Detergent ◽  
Liddle's Syndrome ◽  
Targeting Signal ◽  
Increased Activity

The epithelial Na+ channel (ENaC) plays a key role in the regulation of Na+ and water absorption in several epithelia, including those of the distal nephron, distal colon, and lung. Accordingly, mutations in ENaC leading to reduced or increased channel activity cause human diseases such as pseudohypoaldosteronism type I or Liddle's syndrome, respectively. The gain of ENaC function in Liddle's syndrome is associated with increased activity and stability of the channel at the plasma membrane. Thus understanding the regulation of channel processing and trafficking to and stability at the cell surface is of fundamental importance. This review describes some of the recent advances in our understanding of ENaC trafficking, including the role of glycosylation, ENaC solubility in nonionic detergent, targeting signal(s) and hormones. It also describes the regulation of ENaC stability at the cell surface and the roles of the ubiquitin ligase Nedd4 (and ubiquitination) and clathrin-mediated endocytosis in that regulation.

The Role of the Interaction between Fe(III) and Cell Surface in the Accumulation of 67Ga by Tumor Cells

1991 ◽  
Vol 30 (06) ◽  
pp. 290-293 ◽  
Author(s):  
P. Maleki ◽  
A. Martinezi ◽  
M. C. Crone-Escanye ◽  
J. Robert ◽  
L. J. Anghileri
Keyword(s):  
Cell Surface ◽  
Tumor Cells ◽  
Ionic Composition ◽  
Iron Complex ◽  
Iron Binding ◽  
Complex Time ◽  
Interaction Product ◽  
Thermodynamic Constant ◽  
Number Of Cells

The study of the interaction between complexed iron and tumor cells in the presence of 67Ga-citrate indicates that a phenomenon of iron-binding related to the thermodynamic constant of stability of the iron complex, and a hydrolysis (or anion penetration) of the interaction product determine the uptake of 67Ga. The effects of various parameters such as ionic composition of the medium, nature of the iron complex, time of incubation and number of cells are discussed.

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