Structure and modulation of Fc and complement receptors
Contemporary Topics in Immunobiology
|January 1, 1984
Summary
Researchers identified structures of phagocytosis receptors like C3b, C3bi, and Fc receptors. Some Fc receptors act as ligand-dependent ion channels, initiating signals, while others use uncharacterized pathways.
Area of Science:
- Immunology
- Molecular Biology
- Cell Biology
Background:
- Phagocytosis is crucial for immune response and clearance.
- Receptors mediating phagocytosis, including complement receptors (C3b, C3bi) and Fc receptors, are key players.
- Understanding receptor structure and signaling is vital for deciphering immune mechanisms.
Purpose of the Study:
- To elucidate the structural characteristics of phagocytosis-promoting receptors.
- To investigate the signaling mechanisms initiated by Fc receptors and C3 receptors.
Main Methods:
- Biochemical characterization of receptor subunits.
- Analysis of receptor structure and molecular weight.
- Functional studies on Fc receptor signaling pathways.
Main Results:
- C3b receptor: single-chain glycoprotein (Mr 205,000).
- C3bi receptor: two-chain glycoprotein (Mr 180,000 and 100,000).
- Fc receptors: single-chain glycoproteins (approx. Mr 50,000) with diverse ligand specificities.
- Fc gamma 2b/gamma 1R functions as a ligand-dependent ion channel, initiating proximal signaling.
- Second signaling pathways for other Fc receptors and C3 receptors remain uncharacterized but differ from Fc gamma 2b/gamma 1R.
Conclusions:
- Phagocytosis receptors exhibit distinct structural compositions.
- Fc receptors display heterogeneity in structure and function, with some acting as ion channels.
- The proximal signaling of Fc gamma 2b/gamma 1R involves ion flux, while downstream signaling of various Fc and C3 receptors requires further investigation.
Related Concept Videos
01:10Antibody Structure
Overview
Antibodies, also known as immunoglobulins (Ig), are essential players of the adaptive immune system. These antigen-binding proteins are produced by B cells and make up 20 percent of the total blood plasma by weight. In mammals, antibodies fall into five different classes, which each elicits a different biological response upon antigen binding.
The Y-Shaped Structure of Antibodies Consists of Four Polypeptide Chains
Antibodies consist of four polypeptide chains: two identical heavy...
Antibodies, also known as immunoglobulins (Ig), are essential players of the adaptive immune system. These antigen-binding proteins are produced by B cells and make up 20 percent of the total blood plasma by weight. In mammals, antibodies fall into five different classes, which each elicits a different biological response upon antigen binding.
The Y-Shaped Structure of Antibodies Consists of Four Polypeptide Chains
Antibodies consist of four polypeptide chains: two identical heavy...
01:10Antibody Structure
Overview
Antibodies, also known as immunoglobulins (Ig), are essential players of the adaptive immune system. These antigen-binding proteins are produced by B cells and make up 20 percent of the total blood plasma by weight. In mammals, antibodies fall into five different classes, which each elicits a different biological response upon antigen binding.
The Y-Shaped Structure of Antibodies Consists of Four Polypeptide Chains
Antibodies consist of four polypeptide chains: two identical heavy...
Antibodies, also known as immunoglobulins (Ig), are essential players of the adaptive immune system. These antigen-binding proteins are produced by B cells and make up 20 percent of the total blood plasma by weight. In mammals, antibodies fall into five different classes, which each elicits a different biological response upon antigen binding.
The Y-Shaped Structure of Antibodies Consists of Four Polypeptide Chains
Antibodies consist of four polypeptide chains: two identical heavy...
01:25Selectins
Cell adhesion is an essential aspect of multicellularity. While stable cell interactions usually occur between cells of the same type, transient cell interactions occur between cells of different tissue types, such as between neutrophils and endothelial cells. Selectins are one class of cell adhesion molecules (CAMs) that bind carbohydrate ligands to form transient cell adhesion. They are rod-like proteins with a long extracellular part of variable length ending with the lectin domain, which...
01:31Immunoglobulin-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...
Ig-CAMs exhibit either homophilic binding (to other Ig-CAMs) or heterophilic binding (to other ligands such as integrins). While most Ig-CAMs...
01:30Transducer Mechanism: G Protein–Coupled Receptors
G Protein–Coupled Receptors (GPCRs) are membrane-bound receptors that transiently associate with heterotrimeric G proteins and induce an appropriate response to various stimuli. GPCRs regulate critical physiological pathways and are excellent drug targets for treating diseases such as diabetes, cancer, obesity, depression, or Alzheimer's. Nearly 35% of approved drugs implement their therapeutic effects by selectively interacting with specific GPCRs.
GPCRs are also called heptahelical, 7TM, or...
GPCRs are also called heptahelical, 7TM, or...
01:27Complement System
The complement system is a group of approximately 20 plasma proteins that strengthen the body's defenses against infections through opsonization, inflammation, and cell lysis. Opsonization involves coating pathogens with complement proteins, making them more recognizable and facilitating phagocyte engulfment. Certain complement proteins induce inflammation that attracts immune cells to the site of infection. Cell lysis involves the destruction of pathogens through the formation of a membrane...