Chemokine receptor
G-protein
through which they signal.| Chemokine receptor family | |
|---|---|
| Identifiers | |
| Symbol | Chemokine_rcpt |
| InterPro | IPR000355 |
Chemokine receptors are
CX3C chemokine receptors and XC chemokine receptors that correspond to the 4 distinct subfamilies of chemokines they bind. The four subfamilies of chemokines differ in the spacing of structurally important cysteine residues near the N-terminal of the chemokine.[4]
Structural characteristics
Chemokine receptors are
G-proteins couple to the C-terminal end, which is important for receptor signaling following ligand binding. Although chemokine receptors share high amino acid identity in their primary sequences, they typically bind a limited number of ligands.[6] Chemokine receptors are redundant in their function as more than one chemokine is able to bind to a single receptor.[4]
Signal transduction
inositol triphosphate (IP3) and diacylglycerol (DAG); DAG activates another enzyme called protein kinase C (PKC), and IP3 triggers the release of calcium from intracellular stores. These events promote many signaling cascades, effecting a cellular response.[7]
For example, when CXCL8 (IL-8) binds to its specific receptors,
MAP kinase pathway activates specific cellular mechanisms involved in chemotaxis, degranulation, release of superoxide anions, and changes in the avidity of cell adhesion molecules called integrins.[6] Chemokines and their receptors play a crucial role in cancer metastasis as they are involved in extravasation, migration, micrometastasis, and angiogenesis.[4] This role of chemokine is strikingly similar to their normal function of localizing leukocytes to an inflammatory site.[4]
Selective pressures on Chemokine receptor 5 (CCR5)
variola major belong to the same family of viruses and myxoma has been shown to use CCR5 receptor to enter its host.[11]
Moreover, Yersinia is a bacterium which is biologically distinct from viruses and is unlikely to have similar mechanism of transmission. Recent evidence provides a strong support for smallpox as the selective agent for CCR5-Δ32.
Families
- CXC chemokine receptors (six members)
- CC chemokine receptors (ten/eleven members)
- C chemokine receptors (one member, XCR1)
- CX3C chemokine receptors (one member, CX3CR1)
Fifty chemokines have been discovered so far, and most bind onto CXC and CC families.[4] Two types of chemokines that bind to these receptors are inflammatory chemokines and homeostatic chemokines. Inflammatory chemokines are expressed upon leukocyte activation, whereas homeostatic chemokines show continual expression.[3]
References
External links
- "Chemokine Receptors". IUPHAR Database of Receptors and Ion Channels. International Union of Basic and Clinical Pharmacology. Archived from the original on 2016-03-03. Retrieved 2008-11-25.
- The Cytokine Receptor Database