scholarly journals Alternative Splicing of the C-Terminal Domain Regulates Cell Surface Expression of the NMDA Receptor NR1 Subunit

1999 ◽  
Vol 19 (18) ◽  
pp. 7781-7792 ◽  
Author(s):  
Shigeo Okabe ◽  
Akiko Miwa ◽  
Haruo Okado
Keyword(s):  
Alternative Splicing ◽  
Nmda Receptor ◽  
Cell Surface ◽  
Surface Expression ◽  
Cell Surface Expression ◽  
Terminal Domain

scholarly journals Characterization, cell-surface expression and ligand-binding properties of different truncated N-terminal extracellular domains of the ionotropic glutamate receptor subunit GluR1

1996 ◽  
Vol 315 (1) ◽  
pp. 217-225 ◽  
Author(s):  
R. A. Jeffrey McILHINNEY ◽  
Elek MOLNÁR
Keyword(s):  
Cell Surface ◽  
Ligand Binding ◽  
Glutamate Receptor ◽  
Cell Membranes ◽  
Surface Expression ◽  
Cell Surface Expression ◽  
Receptor Subunit ◽  
Binding Studies ◽  
Terminal Domain ◽  
Glutamate Receptor Subunit

To identify the location of the first transmembrane segment of the GluR1 glutamate receptor subunit artificial stop codons have been introduced into the N-terminal domain at amino acid positions 442, 510 and 563, namely just before and spanning the proposed first two transmembrane regions. The resultant truncated N-terminal fragments of GluR1, termed NT1, NT2 and NT3 respectively were expressed in Cos-7 cells and their cellular distribution and cell-surface expression analysed using an N-terminal antibody to GluR1. All the fragments were fully glycosylated and were found to be associated with cell membranes but none was secreted. Differential extraction of the cell membranes indicated that both NT1 and NT2 behave as peripheral membrane proteins. In contrast NT3, like the full subunit, has integral membrane protein properties. Furthermore only NT3 is expressed at the cell surface as determined by immunofluorescence and cell-surface biotinylation. Protease protection assays indicated that only NT3 had a cytoplasmic tail. Binding studies using the selective ligand [3H]α-amino-3-hydroxy-5-methyl-4-isoxazolepropionate ([3H]AMPA) demonstrated that NT3 does not bind ligand. Together these results indicate that the first transmembrane domain of the GluR1 subunit lies between residues 509 and 562, that the N-terminal domain alone cannot form a functional ligand-binding site and that this domain can be targeted to the cell surface provided that it has a transmembrane-spanning region.

scholarly journals The Amino Terminal Lectin-Like Domain of Thrombomodulin Is Required for Constitutive Endocytosis

Blood ◽  
1997 ◽  
Vol 89 (2) ◽  
pp. 652-661 ◽  
Author(s):  
Edward M. Conway ◽  
Saskia Pollefeyt ◽  
Desiré Collen ◽  
Marta Steiner-Mosonyi
Keyword(s):  
Cell Surface ◽  
Protein C ◽  
Surface Expression ◽  
Cell Surface Expression ◽  
Immunogold Electron Microscopy ◽  
Wild Type ◽  
Hydrophobic Region ◽  
Cos Cells ◽  
Amino Terminal ◽  
Terminal Domain

Abstract Thrombomodulin (TM) is a multidomain protein that serves as a cofactor in a major natural anticoagulant system. To further characterize the structure-function of TM, we have transfected COS cells with different truncated forms of TM. In the first form, COS cells expressing TM that lacks the putative signal peptide (17 residues); the lectin-like, hydrophobic N-terminal domain (226 residues); and 12 residues of the first epidermal growth factor (EGF )-like repeat (COSdel.238 cells) were found to function normally with respect to TM transport to the cell surface and thrombin-dependent protein C activation. However, in contrast to wild-type TM, as visually studied by immunofluorescence and immunogold electron microscopy, the COSdel.238 cells did not constitutively internalize anti-TM–TM or thrombin-TM complexes. To identify the region responsible for mediating the endocytic process, deletant forms of TM lacking either the lectin-like region (residues 2-155) or the hydrophobic region of the N-terminal domain (residues 161-202) were expressed in COS cells (COSdel.2-155 and COSdel.161-202, respectively). Protein C cofactor activity was maintained in both cells. Although the COSdel.161-202 cells behaved similarly to wild-type TM-transfected cells, visual studies showed a lack of constitutive internalization of thrombin-TM or anti-TM–TM complexes in the COSdel.2-155 cells. We conclude that the lectin-like domain of human TM serves to regulate cell surface expression of TM via the endocytic route and therefore may also play a major physiologic role in controlling intracellular and extracellular accumulation of thrombin in a variety of biologic systems.

scholarly journals Phorbol Esters and SDF-1 Induce Rapid Endocytosis and Down Modulation of the Chemokine Receptor CXCR4

1997 ◽  
Vol 139 (3) ◽  
pp. 651-664 ◽  
Author(s):  
Natalie Signoret ◽  
Joanne Oldridge ◽  
Annegret Pelchen-Matthews ◽  
Per J. Klasse ◽  
Thanh Tran ◽  
...  
Keyword(s):  
Cell Surface ◽  
Chemokine Receptor ◽  
Phorbol Esters ◽  
Surface Expression ◽  
Lung Epithelial Cells ◽  
Cell Surface Expression ◽  
Coated Pits ◽  
Terminal Domain ◽  
Chemokine Receptor Cxcr4 ◽  
Hiv 1

The chemokine receptor CXCR4 is required, together with CD4, for entry by some isolates of HIV-1, particularly those that emerge late in infection. The use of CXCR4 by these viruses likely has profound effects on viral host range and correlates with the evolution of immunodeficiency. Stromal cell-derived factor-1 (SDF-1), the ligand for CXCR4, can inhibit infection by CXCR4-dependent viruses. To understand the mechanism of this inhibition, we used a monoclonal antibody that is specific for CXCR4 to analyze the effects of phorbol esters and SDF-1 on surface expression of CXCR4. On human T cell lines SupT1 and BC7, CXCR4 undergoes slow constitutive internalization (1.0% of the cell surface pool/min). Addition of phorbol esters increased this endocytosis rate >6-fold and reduced cell surface CXCR4 expression by 60 to 90% over 120 min. CXCR4 was internalized through coated pits and coated vesicles and subsequently localized in endosomal compartments from where it could recycle to the cell surface after removal of the phorbol ester. SDF-1 also induced the rapid down modulation (half time ∼5 min) of CXCR4. Using mink lung epithelial cells expressing CXCR4 and a COOH-terminal deletion mutant of CXCR4, we found that an intact cytoplasmic COOH-terminal domain was required for both PMA and ligand-induced CXCR4 endocytosis. However, experiments using inhibitors of protein kinase C indicated that SDF-1 and phorbol esters trigger down modulation through different cellular mechanisms. SDF-1 inhibited HIV-1 infection of mink cells expressing CD4 and CXCR4. The inhibition of infection was less efficient for CXCR4 lacking the COOH-terminal domain, suggesting at least in part that SDF-1 inhibition of virus infection was mediated through ligand-induced internalization of CXCR4. Significantly, ligand induced internalization of CXCR4 but not CD4, suggesting that CXCR4 and CD4 do not normally physically interact on the cell surface. Together these studies indicate that endocytosis can regulate the cell-surface expression of CXCR4 and that SDF-1–mediated down regulation of cell-surface coreceptor expression contributes to chemokine-mediated inhibition of HIV infection.

Persistent HIV Transcription Induces Sialyl-Lewis-X Glyco-Antigen Cell-Surface Expression

2020 ◽  
Author(s):  
Florent Colomb ◽  
Leila B. Giron ◽  
Leticia Kuri Cervantes ◽  
Tongcui Ma ◽  
Samson Adeniji ◽  
...  
Keyword(s):  
Cell Surface ◽  
Surface Expression ◽  
Sialyl Lewis X ◽  
Cell Surface Expression ◽  
Lewis X ◽  
Hiv Transcription ◽  
Sialyl Lewis

Influence of β-D-mannuronic acid, as a new member of non-steroidal anti-inflammatory drugs family, on expression pattern of chemokines and their receptors in rheumatoid arthritis

2019 ◽  
Vol 16 ◽  
Author(s):  
Mona Aslani ◽  
Arman Ahmadzadeh ◽  
Zahra Aghazadeh ◽  
Majid Zaki-Dizaji ◽  
Laleh Sharifi ◽  
...  
Keyword(s):  
Cell Surface ◽  
Mrna Expression ◽  
Surface Expression ◽  
Phase Iii ◽  
Cell Surface Expression ◽  
Optimum Dose ◽  
High Dose ◽  
Mannuronic Acid ◽  
Anti Inflammatory ◽  
High Doses

Background: : Based on the encouraging results of phase III clinical trial of β-D-mannuronic acid (M2000) (as a new anti-inflammatory drug) in patients with RA, in this study, we aimed to evaluate the effects of this drug on the expression of chemokines and their receptors in PBMCs of RA patients. Methods:: PBMCs of RA patients and healthy controls were separated and the patients' cells were treated with low, moderate and high doses (5, 25 and 50 μg/mL) of M2000 and optimum dose (1 μg/mL) of diclofenac, as a control in RPMI-1640 medium. Real-time PCR was used for evaluating the mRNA expression of CXCR3, CXCR4, CCR2, CCR5 and CCL2/MCP-1. Cell surface expression of CCR2 was investigated using flow cytometry. Results:: CCR5 mRNA expression reduced significantly, after treatment of the patients' cells with all three doses of M2000 and optimum dose of diclofenac. CXCR3 mRNA expression down-regulated significantly followed by treatment of these cells with moderate and high doses of M2000 and optimum dose of diclofenac. CXCR4 mRNA expression declined significantly after treatment of these cells with moderate and high doses of M2000. CCL2 mRNA expression significantly reduced only followed by treatment of these cells with high dose of M2000, whereas, mRNA and cell surface expressions of CCR2 diminished significantly followed by treatment of these cells with high dose of M2000 and optimum dose of diclofenac. Conclusion:: According to our results, M2000 through the down-regulation of chemokines and their receptors may restrict the infiltration of immune cells into the synovium.

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