Related Experiment Video

Updated: Oct 9, 2026

Isolation Protocol of Mouse Monocyte-derived Dendritic Cells and Their Subsequent In Vitro Activation with Tumor Immune Complexes
11:48

Isolation Protocol of Mouse Monocyte-derived Dendritic Cells and Their Subsequent In Vitro Activation with Tumor Immune Complexes

Published on: May 31, 2018

The Fc-recognizing, collagen-like C1q molecule is a putative type II membrane protein of macrophages

M Kaul1, M Loos

  • 1Institut für Medizinische Mikrobiologie, Hochhaus am Augustusplatz, Mainz, Germany.

Behring Institute Mitteilungen
|December 1, 1993
PubMed

The Fc-recognizing, collagen-like C1q molecule, a subcomponent of the first component of complement, C1, is present on the cell surface of guinea pig peritoneal macrophages and human peritoneal and monocyte-derived macrophages. On closer examination, C1q appears to be a membrane protein (membrane C1q) of macrophages since it is i) anchored into the membrane throughout the biosynthetic pathway, ii) tightly and irreversibly bound to the cell surface and iii) only liberated if the intact membrane structure is disrupted by a detergent or repeated freeze/thawing. Additionally, the amino acid sequence of the A chain of human C1q displays properties that are characteristic for integral type II membrane proteins. The membrane C1q of guinea pig macrophages has a "lighter" B chain than serum C1q. Under physiological conditions in culture guinea pig macrophages release membrane C1q thereby converting it into the serum form. Moreover, membrane C1q appears to be involved in various cellular events such as binding of Fc, polyanions, lipid A and gram-negative bacteria to macrophages.

More Related Videos

Evaluation of the Interplay Between the Complement Protein C1q and Hyaluronic Acid in Promoting Cell Adhesion06:54

Evaluation of the Interplay Between the Complement Protein C1q and Hyaluronic Acid in Promoting Cell Adhesion

Published on: June 15, 2019

A Macrophage Reporter Cell Assay to Examine Toll-Like Receptor-Mediated NF-kB/AP-1 Signaling on Adsorbed Protein Layers on Polymeric Surfaces07:55

A Macrophage Reporter Cell Assay to Examine Toll-Like Receptor-Mediated NF-kB/AP-1 Signaling on Adsorbed Protein Layers on Polymeric Surfaces

Published on: January 7, 2020

Related Concept Videos

Structural Protein Function01:56

Structural Protein Function

Structural proteins are a category of proteins responsible for functions ranging from cell shape and movement to providing support to major structures such as bones, cartilage, hair, and muscles. This group includes proteins such as collagen, actin, myosin, and keratin.
Collagen, the most abundant protein in mammals, is found throughout the body. In connective tissue, such as skin, ligaments, and tendons, it provides tensile strength and elasticity.  In bones and teeth, it mineralizes to form...
Collagens are the Major Structural Proteins of ECM01:13

Collagens are the Major Structural Proteins of ECM

Three main types of fibers are secreted by fibroblasts: collagen fibers, elastic fibers, and reticular fibers. Collagen fiber is made from fibrous protein subunits linked together to form a long, straight fiber. Collagen fibers, while flexible, have great tensile strength, resist stretching, and give ligaments and tendons their characteristic resilience and strength. These fibers hold connective tissues together, even during the body's movement.
Connective tissue proper includes loose...
Fibril-associated Collagen01:11

Fibril-associated Collagen

Fibril-associated collagens are a type of collagens present in the extracellular matrix with interrupted triple helices or FACIT (Fibril-associated collagens interrupted triple-helices). FACIT help connect and attach the collagen fibrils with each other as well as with other proteins of the extracellular matrix.
For example, the type II collagen fibrils in cartilage have covalently bound type IX fibril-associated collagens at regular intervals. Other types of fibril-associated collagens are...
Matrix Proteoglycans and Glycoproteins01:21

Matrix Proteoglycans and Glycoproteins

Proteoglycans are extensively glycosylated proteins, commonly found in the extracellular matrix, interwoven with collagen fibers. Hyaline cartilage, the most common type of cartilage in the body, consists of short and dispersed collagen fibers associated with large amounts of proteoglycans. These proteoglycans have long negative charges that attract cations, which in turn attract water molecules. This influx of ions and water molecules swells up the proteoglycan like a water-soaked gel that can...
Type IV Collagen of Basal Lamina01:05

Type IV Collagen of Basal Lamina

Type IV collagen is a 400 nm long, network-forming collagen that acts as a barrier between the epithelial and endothelial cells. Type IV collagen  forms the backbone of the basement membrane by scaffolding with laminin, entactin, proteoglycans, and fibronectin. Apart from rendering structural support to the basement membrane, it also helps entail signaling potentials necessary for both pathological and physiological functions.
A type IV collagen molecule has six alpha chains which can exist in...
Immunoglobulin-like Cell Adhesion Molecules01:31

Immunoglobulin-like Cell Adhesion Molecules

Immunoglobulin-like cell adhesion molecules or Ig-CAMs are a versatile group of cell surface glycoproteins belonging to the immunoglobulin protein superfamily. Ig-CAMs possess the characteristic immunoglobulin protein domains and other domains such as the fibronectin type III domain. The Ig domains are glycosylated to varying degrees in different Ig-CAMs.
Ig-CAMs exhibit either homophilic binding (to other Ig-CAMs) or heterophilic binding (to other ligands such as integrins). While most Ig-CAMs...