What Is a Cytokine Receptor?

Cytokines play a biological role by binding to the corresponding cytokine receptors on the cell surface. The binding of cytokines and their receptors is the initiating stimulus of cytokine-mediated cellular signal transduction. The vast majority of known cytokine receptors are transmembrane proteins, consisting of extracellular, transmembrane, and cytoplasmic regions.

Cytokine receptor

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The class I cytokine receptor family includes IL-2, IL-3, IL-4, IL-5, IL-7, IL-9, IL-13, IL-15, GM-CSF and Receptor for cytokines such as erythropoietin. The class II cytokine receptor family includes IFN, IFN, IFN, and IL-10 receptors. TNF receptor super family (TNFSF) includes TNF receptor, nerve growth factor receptor, CD40 molecule and Fas molecule. The chemokine receptor family is a G-protein coupled receptor, which is a seven-transmembrane protein. After binding to the corresponding ligand, it is coupled to the GTP-binding protein to exert a biological effect.

CCR5 is a co-receptor of HIV on macrophages and T lymphocytes, which HIV uses to enter cells to cause primary infections. In vitro experiments, small molecule antagonists of CCR5 can inhibit HIV infection of macrophages. CCR5 is a polymorphic gene. A homozygous individual carrying a CCR5 allele, which has a frameshift mutation in the coding region due to the absence of 32 bases, only expresses non-functional CCR5, and this individual can resist HIV infection to a certain extent.

Most members of the type I cytokine receptor family receptors are multiple subunit receptors, one of which is a cytokine binding subunit and the other a single subunit of signal transduction. Multiple type I cytokine receptors share the same signaling subunit. For example, human IL-3, IL-5, and GM-CSF receptors are composed of and subunits, where subunits are cytokine-specific binding subunits with different structures, and subunits are these three cytokines Shared signal transduction subunit. Therefore, IL-3, IL-5 and GM-CSF have a great overlap in function, for example, they can all act on hematopoietic stem cells. The IL-2, IL-4, IL-7, IL-9 and IL-15 receptors all have the same signal transduction subunit (gamma chain).

Defects in the gamma-chain gene on the X-chromosome are a cause of X-linked severe severe immunodeficiency disease (SCID). These patients are composed of IL-2, IL-4, IL-7, IL-9, and 15 Receptor-mediated cellular signal transduction has severe obstacles, and both cellular and humoral immunity have serious defects. Many cytokines such as IL-1, IL-2, IL-4, IL-5, IL-6, IL-7, IL-8, G-CSF, GM-CSF, IFN-, and TNF have free receptors The form is soluble cytokinereceptor. Soluble cytokine receptors can be used as the carrier of the corresponding cytokines, and they can also compete with the corresponding membrane-type receptors for ligand inhibition. In addition, the detection of certain soluble cytokines is helpful in the diagnosis of certain diseases and in the monitoring of the development and outcome of the course.

Type II cytokine receptors are dimers formed from homologous two molecules. Some cytokine receptors have natural antagonists. For example, IL-1 receptor antagonist (IL-1Ra) is a 170kDa peptide produced by monocytes. It can bind to the IL-1 receptor and inhibit IL. Biological activity of -1 and IL-1. Some viruses produce cytokine-binding proteins that are also cytokine antagonists, such as the TNF and IL-1 binding proteins produced by pox virus, which can inhibit or eliminate the inflammatory effects of TNF and IL-1.