FCER1

Human biomolecule

The structure of the FcεRI receptor Summary of IgE/FcεRI receptor mediated downward signal cascade High-affinity IgE receptor; alpha

Identifiers
Symbol| FCER1A
Alt. symbols| FcεRIα, FCE1A
NCBI gene| 2205
HGNC| 3609
OMIM| 147140
RefSeq| NM_002001
UniProt| P12319
Other data
Locus| Chr. 1 q23
| Search for

Structures| Swiss-model
Domains| InterPro
High affinity IgE receptor; beta

Identifiers
Symbol| MS4A2
Alt. symbols| FcεRIβ, FCER1B, IGER, APY
NCBI gene| 2206
HGNC| 7316
OMIM| 147138
RefSeq| NM_000139
UniProt| Q01362
Other data
Locus| Chr. 1 q23
| Search for

Structures| Swiss-model
Domains| InterPro
High affinity IgE receptor; gamma

Identifiers
Symbol| FCER1G
Alt. symbols| FcεRIγ
NCBI gene| 2207
HGNC| 3611
OMIM| 147139
RefSeq| NM_004106
UniProt| P30273
Other data
Locus| Chr. 1 q23
| Search for

Structures| Swiss-model
Domains| InterPro

The high-affinity IgE receptor, also known as FcεRI, or Fc epsilon RI, is the high-affinity receptor for the Fc region of immunoglobulin E (IgE), an antibody isotype involved in allergy disorders and parasite immunity. FcεRI is a tetrameric receptor complex that binds Fc portion of the ε heavy chain of IgE.[1] It consists of one alpha (FcεRIα – antibody binding site), one beta (FcεRIβ – which amplifies the downstream signal), and two gamma chains (FcεRIγ – the site where the downstream signal initiates) connected by two disulfide bridges on mast cells and basophils. It lacks the beta subunit on other cells. It is constitutively expressed on mast cells and basophils[2] and is inducible in eosinophils.

## Tissue distribution

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FcεRI is found on epidermal Langerhans cells, eosinophils, mast cells, and basophils.[3][4][5] 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 (cytokines, interleukins, leukotrienes, and prostaglandins) that promote inflammation.[6] The most known mediator is histamine, which results in the five symptoms of inflammation: heat, swelling, pain, redness and loss of function.

FcεRI was demonstrated in bronchial/tracheal airway smooth muscle cells in normal and asthmatic patients. FcεRI cross-linking by IgE and anti-IgE antibodies led to Th2 (IL-4, -5, and -13) cytokines and CCL11/eotaxin-1 chemokine release; and ([Ca2+]i) mobilization, suggesting a likely IgE-FcεRI-ASM (airway smooth muscle cell)-mediated link to airway inflammation and airway hyperresponsiveness.[7][8]

## Mechanism of action

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Crosslinking of the FcεRI via IgE-antigen complexes leads to degranulation of mast cells or basophils and release of inflammatory mediators.[9] Under laboratory conditions, degranulation of isolated basophils can also be induced with antibodies to the FcεRIα, which crosslink the receptor. Such crosslinking and potentially pathogenic autoantibodies to the FcεRIα have been isolated from human cord blood, which suggest that they occur naturally and are present already at birth. However, their epitope on FcεRIα was masked by IgE, and the affinity of the corresponding autoantibodies found in healthy adults appeared lowered.[10]

## See also

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* Omalizumab

## References

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1. ^ Kumar, Vinay; Abbas, Abul K.; Aster, Jon (2012-05-01). Robbins Basic Pathology (9 ed.). Saunders.
2. ^ Pawankar R (February 2001). "Mast cells as orchestrators of the allergic reaction: the IgE-IgE receptor mast cell network". Current Opinion in Allergy and Clinical Immunology. 1 (1): 3–6\. doi:10.1097/00130832-200102000-00002. PMID 11964662.
3. ^ Ochiai K, Wang B, Rieger A, Kilgus O, Maurer D, Födinger D, Kinet J, Stingl G, Tomioka H (1994). "A review on Fc epsilon RI on human epidermal Langerhans cells". International Archives of Allergy and Immunology. 104. Suppl 1 (1): 63–64\. doi:10.1159/000236756. PMID 8156009.
4. ^ Prussin C, Metcalfe D (1994). "5". Nature. 367 (6459): 183–6\. doi:10.1038/367183a0. PMID 8114916. S2CID 4331405.
5. ^ Gounni, A.; Lamkhioued, B.; Ochiai, K.; Tanaka, Y.; Delaporte, E.; Capron, A.; Kinet, J.P.; Capron, M. (2006). "IgE, mast cells, basophils, and eosinophils". Journal of Allergy and Clinical Immunology. 117 (2 Suppl Mini–Primer): S450–5456. doi:10.1016/j.jaci.2005.11.016. PMID 16455345.
6. ^ von Bubnoff D, Novak N, Kraft S, Bieber T (2003). "The central role of FcepsilonRI in allergy". Clinical and Experimental Dermatology. 28 (2): 184–187\. doi:10.1046/j.1365-2230.2003.01209.x. PMID 12653710. S2CID 2080598.
7. ^ Gounni, A.S.; Wellemans, V.; Yang, J.; Bellesort, F.; Kassiri, K.; Gangloff, S.; Guenounou, M.; Halayko, A.J.; Hamid, Q.; Lamkhioued, B. (August 15, 2005). "Human airway smooth muscle cells express the high affinity receptor for IgE (Fc epsilon RI): a critical role of Fc epsilon RI in human airway smooth muscle cell function". Journal of Immunology. 175 (4): 2613–2621\. doi:10.4049/jimmunol.175.4.2613. PMID 16081836.
8. ^ Gounni, A.S. (September 2006). "The high-affinity IgE receptor (FcepsilonRI): a critical regulator of airway smooth muscle cells?". American Journal of Physiology. 291 (3): L312-321. doi:10.1152/ajplung.00005.2006. PMID 16581830.
9. ^ Siraganian RP (December 2003). "Mast cell signal transduction from the high-affinity IgE receptor". Current Opinion in Immunology. 15 (6): 639–646\. doi:10.1016/j.coi.2003.09.010. PMID 14630197. S2CID 39294873.
10. ^ Bobrzynski T, Fux M, Vogel M, Stadler MB, Stadler BM, Miescher SM (November 2005). "A high-affinity natural autoantibody from human cord blood defines a physiologically relevant epitope on the FcepsilonRIalpha". Journal of Immunology. 175 (10): 6589–6596\. doi:10.4049/jimmunol.175.10.6589. PMID 16272313.

## External links

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* Fc+epsilon+RI at the U.S. National Library of Medicine Medical Subject Headings (MeSH)

* v
* t
* e

Transmembrane receptors: immunoglobulin superfamily immune receptors

Antibody receptor:
Fc receptor|

| Epsilon (ε)|

* FcεRI
* (FcεRII is C-type lectin)

|

Gamma (γ)|

* FcγRI
* FcγRII
* FcγRIII
* Neonatal

Alpha (α)/mu (μ)|

* FcαRI
* Fcα/μR

Secretory|

* Polymeric immunoglobulin receptor

Antigen receptor|

| B cells|

| Antigen receptor|

* BCR

|

Co-receptor|

| stimulate:|

* CD21/CD19/CD81

|

inhibit:|

* CD22

Accessory molecules|

* Ig-α/Ig-β (CD79)

T cells|

| Ligands|

* MHC
* MHC class I
* MHC class II

|

Antigen receptor|

* TCR: TRA@
* TRB@
* TRD@
* TRG@

Co-receptors|

* CD8 (with two glycoprotein chains CD8α and CD8β)
* CD4

Accessory molecules|

* CD3
* CD3γ
* CD3δ
* CD3ε
* ζ-chain (also called CD3ζ and TCRζ)

Cytokine receptor|

* see cytokine receptors

Killer-cell IG-like receptors|

* KIR2DL1
* KIR2DL2
* KIR2DL3
* KIR2DL4
* KIR2DL5A
* KIR2DL5B
* KIR2DS1
* KIR2DS2
* KIR2DS3
* KIR2DS4
* KIR2DS5
* KIR3DL1
* KIR3DL2
* KIR3DL3
* KIR3DS1

Leukocyte IG-like receptors|

* LILRA1
* LILRA2
* LILRA3
* LILRA4
* LILRA5
* LILRA6
* LILRB1
* LILRB2
* LILRB3
* LILRB4
* LILRB5

*[v]: View this template
*[t]: Discuss this template
*[e]: Edit this template