scholarly journals DC-SIGN, C1q, and gC1qR form a trimolecular receptor complex on the surface of monocyte-derived immature dendritic cells

Blood ◽  
2012 ◽  
Vol 120 (6) ◽  
pp. 1228-1236 ◽  
Author(s):  
Kinga K. Hosszu ◽  
Alisa Valentino ◽  
Uma Vinayagasundaram ◽  
Rama Vinayagasundaram ◽  
M. Gordon Joyce ◽  
...  
Keyword(s):  
Immunofluorescence Microscopy ◽  
Binding Pocket ◽  
Receptor Complex ◽  
Surface Plasmon Resonance Analysis ◽  
Resonance Analysis ◽  
Antigen Capture ◽  
Immature Dendritic Cells ◽  
A Chain ◽  
And Function ◽  
Cell Signaling Pathways

AbstractC1q modulates the differentiation and function of cells committed to the monocyte-derived dendritic cell (DC) lineage. Because the 2 C1q receptors found on the DC surface—gC1qR and cC1qR—lack a direct conduit into intracellular elements, we postulated that the receptors must form complexes with transmembrane partners. In the present study, we show that DC-SIGN, a C-type lectin expressed on DCs, binds directly to C1q, as assessed by ELISA, flow cytometry, and immunoprecipitation experiments. Surface plasmon resonance analysis revealed that the interaction was specific, and both intact C1q and the globular portion of C1q bound to DC-SIGN. Whereas IgG reduced this binding significantly, the Arg residues (162-163) of the C1q-A chain, which are thought to contribute to the C1q-IgG interaction, were not required for C1q binding to DC-SIGN. Binding was reduced significantly in the absence of Ca2+ and by preincubation of DC-SIGN with mannan, suggesting that C1q binds to DC-SIGN at its principal Ca2+-binding pocket, which has increased affinity for mannose residues. Antigen-capture ELISA and immunofluorescence microscopy revealed that C1q and gC1qR associate with DC-SIGN on blood DC precursors and immature DCs. The results of the present study suggest that C1q/gC1qR may regulate DC differentiation and function through the DC-SIGN–mediated induction of cell-signaling pathways.

scholarly journals Actin-membrane interaction in fibroblasts: what proteins are involved in this association?

1984 ◽  
Vol 99 (1) ◽  
pp. 95s-103s ◽  
Author(s):  
P Mangeat ◽  
K Burridge
Keyword(s):  
Plasma Membrane ◽  
Actin Filaments ◽  
Stress Fiber ◽  
Membrane Interaction ◽  
Microfilament Bundles ◽  
The Family ◽  
Form Part ◽  
Membrane Attachment ◽  
A Chain ◽  
And Function

In this review we discuss some of the proteins for which a role in linking actin to the fibroblast plasma membrane has been suggested. We focus on the family of proteins related to erythrocyte spectrin, proteins that have generally been viewed as having an organization and a function in actin-membrane attachment similar to those of erythrocyte spectrin. Experiments in which we precipitated the nonerythrocyte spectrin within living fibroblasts have led us to question this supposed similarity of organization and function of the nonerythrocyte and erythrocyte spectrins. Intracellular precipitation of fibroblast spectrin does not affect the integrity of the major actin-containing structures, the stress fiber microfilament bundles. Unexpectedly, however, we found that the precipitation of spectrin results in a condensation and altered distribution of the vimentin class of intermediate filaments in most cells examined. Although fibroblast spectrin may have a role in the attachment of some of the cortical, submembranous actin, it is surprising how little the intracellular immunoprecipitation of the spectrin affects the cells. Several proteins have been found concentrated at the ends of stress fibers, where the actin filaments terminate at focal contacts. Two of these proteins, alpha-actinin and fimbrin, have properties that suggest that they are not involved in the attachment of the ends of the bundles to the membrane but are more probably involved in the organization and cross-linking of the filaments within the bundles. On the other hand, vinculin and talin are two proteins that interact with each other and may form part of a chain of attachments between the ends of the microfilament bundles and the focal contact membrane. Their role in this attachment, however, has not been established and further work is needed to examine their interaction with actin and to identify any other components with which they may interact, particularly in the plasma membrane.

scholarly journals Crystal structure and RNA-binding properties of an Hfq homolog from the deep-branching Aquificae: conservation of the lateral RNA-binding mode

2017 ◽  
Vol 73 (4) ◽  
pp. 294-315 ◽  
Author(s):  
Kimberly A. Stanek ◽  
Jennifer Patterson-West ◽  
Peter S. Randolph ◽  
Cameron Mura
Keyword(s):  
Rna Binding ◽  
Binding Pocket ◽  
Binding Mode ◽  
Evolutionary Conservation ◽  
Aquifex Aeolicus ◽  
Binding Properties ◽  
Bacterial Phyla ◽  
Mrna Targets ◽  
Small Regulatory Rnas ◽  
And Function

The host factor Hfq, as the bacterial branch of the Sm family, is an RNA-binding protein involved in the post-transcriptional regulation of mRNA expression and turnover. Hfq facilitates pairing between small regulatory RNAs (sRNAs) and their corresponding mRNA targets by binding both RNAs and bringing them into close proximity. Hfq homologs self-assemble into homo-hexameric rings with at least two distinct surfaces that bind RNA. Recently, another binding site, dubbed the `lateral rim', has been implicated in sRNA·mRNA annealing; the RNA-binding properties of this site appear to be rather subtle, and its degree of evolutionary conservation is unknown. An Hfq homolog has been identified in the phylogenetically deep-branching thermophileAquifex aeolicus(Aae), but little is known about the structure and function of Hfq from basal bacterial lineages such as the Aquificae. Therefore,AaeHfq was cloned, overexpressed, purified, crystallized and biochemically characterized. Structures ofAaeHfq were determined in space groupsP1 andP6, both to 1.5 Å resolution, and nanomolar-scale binding affinities for uridine- and adenosine-rich RNAs were discovered. Co-crystallization with U6RNA reveals that the outer rim of theAaeHfq hexamer features a well defined binding pocket that is selective for uracil. ThisAaeHfq structure, combined with biochemical and biophysical characterization of the homolog, reveals deep evolutionary conservation of the lateral RNA-binding mode, and lays a foundation for further studies of Hfq-associated RNA biology in ancient bacterial phyla.

Structure and function of the CD94 C-type lectin receptor complex involved in recognition of HLA class I molecules

1997 ◽  
Vol 155 (1) ◽  
pp. 165-174 ◽  
Author(s):  
Miguel Lopez-Botet ◽  
Juan J. Perez-Villar ◽  
Marta Carretero ◽  
Antonio Rodriguez ◽  
Ignacio Melero ◽  
...  
Keyword(s):  
Hla Class I ◽  
Structure And Function ◽  
Class I ◽  
Receptor Complex ◽  
Lectin Receptor ◽  
Hla Class I Molecules ◽  
And Function

scholarly journals Surface plasmon resonance analysis at a supported lipid monolayer

1998 ◽  
Vol 1373 (1) ◽  
pp. 101-111 ◽  
Author(s):  
Matthew A. Cooper ◽  
Andrew C. Try ◽  
Joe Carroll ◽  
David J. Ellar ◽  
Dudley H. Williams
Keyword(s):  
Surface Plasmon Resonance ◽  
Surface Plasmon ◽  
Plasmon Resonance ◽  
Lipid Monolayer ◽  
Surface Plasmon Resonance Analysis ◽  
Resonance Analysis

Regulation and function of the CGRP receptor complex in human granulopoiesis

2002 ◽  
Vol 30 (4) ◽  
pp. 306-312 ◽  
Author(s):  
Marit D Harzenetter ◽  
Ulrich Keller ◽  
Sandra Beer ◽  
Claudia Riedl ◽  
Christian Peschel ◽  
...  
Keyword(s):  
Receptor Complex ◽  
Cgrp Receptor ◽  
And Function

scholarly journals Identification of Neutrophil Granule Glycoproteins as Lewisx-containing Ligands Cleared by the Scavenger Receptor C-type Lectin

2011 ◽  
Vol 286 (27) ◽  
pp. 24336-24349 ◽  
Author(s):  
Sarah A. Graham ◽  
Aristotelis Antonopoulos ◽  
Paul G. Hitchen ◽  
Stuart M. Haslam ◽  
Anne Dell ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Distributed System ◽  
Scavenger Receptor ◽  
Immunohistochemical Analysis ◽  
Affinity Binding ◽  
Surface Plasmon Resonance Analysis ◽  
Resonance Analysis ◽  
High Affinity ◽  
The Common ◽  
Micromolar Range

The scavenger receptor C-type lectin (SRCL) is a glycan-binding receptor that has the capacity to mediate endocytosis of glycoproteins carrying terminal Lewisx groups (Galβ1–4(Fucα1–3)GlcNAc). A screen for glycoprotein ligands for SRCL using affinity chromatography on immobilized SRCL followed by mass spectrometry-based proteomic analysis revealed that soluble glycoproteins from secondary granules of neutrophils, including lactoferrin and matrix metalloproteinases 8 and 9, are major ligands. Binding competition and surface plasmon resonance analysis showed affinities in the low micromolar range. Comparison of SRCL binding to neutrophil and milk lactoferrin indicates that the binding is dependent on cell-specific glycosylation in the neutrophils, as the milk form of the glycoprotein is a much poorer ligand. Binding to neutrophil glycoproteins is fucose-dependent, and mass spectrometry-based glycomic analysis of neutrophil and milk lactoferrin was used to establish a correlation between high affinity binding to SRCL and the presence of multiple clustered terminal Lewisx groups on a heterogeneous mixture of branched glycans, some with poly N-acetyllactosamine extensions. The ability of SRCL to mediate uptake of neutrophil lactoferrin was confirmed using fibroblasts transfected with SRCL. The common presence of Lewisx groups in granule protein glycans can thus target granule proteins for clearance by SRCL. PCR and immunohistochemical analysis confirm that SRCL is widely expressed on endothelial cells and thus represents a distributed system that could scavenge released neutrophil glycoproteins both locally at sites of inflammation or systemically when they are released in the circulation.

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