Cytokine receptors are receptors that bind to 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 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.
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 | 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. Many have a FN-III superfamily domain and an immunoglobulin-like fold. | JAK phosphorylate and activate downstream proteins involved in their signal transduction pathways | |
| |||
| Many members of the immunoglobulin superfamily | Share structural homology with immunoglobulins (antibodies), cell adhesion molecules, and even some cytokine. Includes with the two classes above. | ||
| Tumor necrosis factor receptor family | cysteine-rich common extracellular binding domain | ||
| chemokine receptors |
| Seven transmembrane helix, rhodopsin-like receptor[2] | G protein-coupled |
| TGF-beta receptor family | Serine/threonine kinase receptors | Dimeric TGFBR2 binds to TGFB and phosphorylates TGFBR1, which phosphorylates the SMADs. See TGF beta signaling pathway. | |
Cytokine receptors may be both membrane-bound and soluble. Soluble cytokine receptors are extremely common regulators of cytokine function. Soluble cytokine receptors typically consist of the extracellular portions of membrane-bound receptors. .[3]