Cytokine receptor
Cytokine receptors are receptors that bind cytokines.[1]
In recent years, the cytokine receptors have come to demand the attention of more investigators than cytokines themselves, partly because of their remarkable characteristics, and partly because a deficiency of cytokine receptors has now been directly linked to certain debilitating immunodeficiency states. In this regard, and also because the redundancy and pleiotropy of cytokines are, in fact, a consequence of their homologous receptors, many authorities are now of the opinion that a classification of cytokine receptors would be more clinically and experimentally useful.
Classification
A classification of cytokine receptors based on their three-dimensional structure has been attempted. (Such a classification, though seemingly cumbersome, provides several unique perspectives for attractive pharmacotherapeutic targets.)
- Type I cytokine receptors, whose members have certain conserved motifs in their extracellular amino-acid domain. The IL-2 receptor belongs to this chain, whose γ-chain (common to several other cytokines) deficiency is directly responsible for the x-linked form of Severe Combined Immunodeficiency (X-SCID).
- Type II cytokine receptors, whose members are receptors mainly for interferons.
- Immunoglobulin (Ig) superfamily, which are ubiquitously present throughout several cells and tissues of the vertebrate body
- Tumor necrosis factor receptor family, whose members share a cysteine-rich common extracellular binding domain, and includes several other non-cytokine ligands like receptors, CD40, CD27 and CD30, besides the ligands on which the family is named (TNF).
- Chemokine receptors, two of which acting as binding proteins for HIV (CXCR4 and CCR5). They are G protein coupled receptors.
- TGF beta receptors
Comparison
| Type | Examples | Structure | Mechanism |
|---|---|---|---|
| type I cytokine receptor |
|
Certain conserved motifs in their extracellular amino-acid domain. Connected to Janus kinase (JAK) family of tyrosine kinases | JAK phosphorylate and activate downstream proteins involved in their signal transduction pathways |
| type II cytokine receptor |
| ||
| Many members of the immunoglobulin superfamily | Share structural homology with immunoglobulins (antibodies), cell adhesion molecules, and even some cytokines. | ||
| Tumor necrosis factor receptor family | cysteine-rich common extracellular binding domain | ||
| chemokine receptors |
|
Seven transmembrane helix | G protein-coupled |
| TGF beta receptors | |||
Solubility
Cytokine receptors may be both membrane-bound and soluble. Soluble cytokine receptors are extremely common regulators of cytokine function.
See also
References
- ↑ Richard Coico; Geoffrey Sunshine (2009). Immunology: a short course. Wiley-Blackwell. pp. 174–. ISBN 978-0-470-08158-7. Retrieved 28 November 2010.
External links
- Cytokine receptors at the US National Library of Medicine Medical Subject Headings (MeSH)
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||