Fc 수용체

Sino Biological offers a comprehensive set of tools for Fc receptor related studies, including recombinant proteins, antibodies (rabbit mAbs, mouse mAbs, and rabbit pAbs), ELISA kits, and ORF cDNA clones.

Fc Receptor Products

• Fc alpha RI / CD89
• Fc gamma RII / CD32
• Fc Receptor-Like 1 / FCRL1
• Fc epsilon RII / CD23
• Fc gamma RIIIA / CD16a
• Fc gamma RI / CD64
• Fc gamma RIIIB / CD16b

Fc Receptor Background

An Fc receptor is a protein found on the surface of certain cells - including natural killer cells, macrophages, neutrophils, and mast cells - that contribute to the protective functions of the immune system. Its name is derived from its binding specificity for a part of an antibody known as the Fc (Fragment, crystallizable) region. Fc receptors bind to antibodies that are attached to infected cells or invading pathogens. Their activity stimulates phagocytic or cytotoxic cells to destroy microbes, or infected cells by antibody-mediated phagocytosis or antibody-dependent cell-mediated cytotoxicity. Some viruses such as flaviviruses use Fc receptors to help them infect cells, by a mechanism known as antibody-dependent enhancement of infection.

Classes of Fc receptor

There are several different types of Fc receptors, which are classified based on the type of antibody that they recognize. The Latin letter used to identify a type of antibody is converted into the corresponding Greek letter, which is placed after the 'Fc' part of the name. For example, those that bind the most common class of antibody, IgG, are called Fc-gamma receptors(FcγR), those that bind IgA are called Fc-alpha receptors (FcαR) and those that bind IgE are called Fc-epsilon receptors (FcεR).

Fc-gamma receptors All FcγRs belong to the immunoglobulin superfamily and are the most important Fc receptors for inducing phagocytosis of opsonized (coated) microbes. This family includes several members, FcγRI (CD64), FcγRIIA (CD32), FcγRIIB (CD32), FcγRIIIA (CD16a), FcγRIIIB (CD16b), which differ in their antibody affinities due to their different molecular structure.For instance, FcγRI binds to IgG more strongly than FcγRII or FcγRIII does. FcγRI also has an extracellular portion composed of three immunoglobulin (Ig)-like domains, one more domain than FcγRII or FcγRIII has. This property allows activation of FcγRI by a sole IgG molecule (or monomer), while the latter two Fcγ receptors must bind multiple IgG molecules within an immune complex to be activated.

Another FcR is expressed on multiple cell types and is similar in structure to MHC class I. This receptor also binds IgG and is involved in preservation of this antibody. However, since this Fc receptor is also involved in transferring IgG from a mother either via the placenta to her fetus or in milk to her suckling infant, it is called the neonatal Fc receptor (FcRn).Recently, research suggested that this receptor plays a role in the homeostasis of IgG serum levels.

Fc-alpha receptors Only one Fc receptor belongs to the FcαR subgroup, which is called FcαRI (or CD89). FcαRI is found on the surface of neutrophils, eosinophils, monocytes, some macrophages (including Kupffer cells), and some dendritic cells.It is composed of two extracellular Ig-like domains, and is a member of both the immunoglobulin superfamily and the multi-chain immune recognition receptor (MIRR) family.It signals by associating with two FcRγ signaling chains.Another receptor can also bind IgA, although it has higher affinity for another antibody called IgM.This receptor is called the Fc-alpha/mu receptor (Fcα/μR) and is a type I transmembrane protein. With one Ig-like domain in its extracellular portion, this Fc receptor is also a member of the immunoglobulin superfamily.

Fc-epsilon receptors The high-affinity receptor FcεRI is a member of the immunoglobulin superfamily (it has two Ig-like domains). FcεRI is found on epidermal Langerhans cells, eosinophils, mast cells and basophils.As a result of its cellular distribution, this receptor plays a major role in controlling allergic responses. FcεRI is also expressed on antigen-presenting cells, and controls the production of important immune mediators called cytokines that promote inflammation.

The low-affinity receptor FcεRII (CD23) is a C-type lectin. FcεRII has multiple functions as a membrane-bound or soluble receptor; it controls B cell growth and differentiation and blocks IgE-binding of eosinophils, monocytes, and basophils.

Fc Receptor Related Studies

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