Interleukins (ILs) are a group of cytokines that were first seen to be expressed by white blood cells (leukocytes). ILs can be divided into four major groups based on distinguishing structural features. However, their amino acid sequence similarity is rather weak. The human genome encodes more than 50 interleukins and related proteins.
Interleukin 10 (IL-10), also known as human cytokine synthesis inhibitory factor (CSIF), is an anti-inflammatory cytokine. In humans, interleukin 10 is encoded by the IL10 gene. IL-10 signals through a receptor complex consisting of two IL-10 receptor-1 and two IL-10 receptor-2 proteins. Consequently, the functional receptor consists of four IL-10 receptor molecules. IL-10 binding induces STAT3 signalling via the phosphorylation of the cytoplasmic tails of IL-10 receptor 1 + IL-10 receptor 2 by JAK1 and Tyk2 respectively.
Interleukin-2 (IL-2) is an interleukin, a type of cytokine signaling molecule in the immune system. It is a 15.5 - 16 kDa protein that regulates the activities of white blood cells (leukocytes, often lymphocytes) that are responsible for immunity. IL-2 is part of the body's natural response to microbial infection, and in discriminating between foreign ("non-self") and "self". IL-2 mediates its effects by binding to IL-2 receptors, which are expressed by lymphocytes. The major sources of IL-2 are activated CD4+ T cells, activated CD8+ T cells, NK cells, dendritic cells and macrophages.
The interleukin 4 is a cytokine that induces differentiation of naive helper T cells to Th2 cells. Upon activation by IL-4, Th2 cells subsequently produce additional IL-4 in a positive feedback loop. The cell that initially produces IL-4, thus inducing Th2 differentiation, has not been identified, but recent studies suggest that basophils may be the effector cell. It is closely related and has functions similar to Interleukin 13.
Interleukin 3 (IL-3) is a protein that in humans is encoded by the IL3 gene.
The common gamma chain (γc), also known as interleukin-2 receptor subunit gamma or IL-2RG, is a cytokine receptor sub-unit that is common to the receptor complexes for at least six different interleukin receptors: IL-2, IL-4, IL-7, IL-9, IL-15 and interleukin-21 receptor. The γc glycoprotein is a member of the type I cytokine receptor family expressed on most lymphocyte populations, and its gene is found on the X-chromosome of mammals.
Interleukin 21 (IL-21) is a protein that in humans is encoded by the IL21 gene.
Interleukin 17A is a pro-inflammatory cytokine. This cytokine is produced by a group of T helper cell known as T helper 17 cell in response to their stimulation with IL-23. Originally, Th17 was identified in 1993 by Rouvier et al. who isolated IL17 transcript from a rodent T-cell hybridoma. The protein encoded by IL17A is a founding member of IL-17 family. IL17 protein exhibits a high homology with a viral IL-17-like protein encoded in the genome of T-lymphotropic rhadinovirus Herpesvirus saimiri. In rodents, IL-17 is often referred to as CTLA8.
Type II cytokine receptors are transmembrane proteins that are expressed on the surface of certain cells, which bind and respond to a select group of cytokines. These receptors are similar to type I cytokine receptors except they do not possess the signature sequence WSXWS that is characteristic of type I receptors.
Glycoprotein 130 is a transmembrane protein which is the founding member of the class of all cytokine receptors. It forms one subunit of the type I cytokine receptor within the IL-6 receptor family. It is often referred to as the common gp130 subunit, and is important for signal transduction following cytokine engagement. As with other type I cytokine receptors, gp130 possesses a WSXWS amino acid motif that ensures correct protein folding and ligand binding. It interacts with Janus kinases to elicit an intracellular signal following receptor interaction with its ligand. Structurally, gp130 is composed of five fibronectin type-III domains and one immunoglobulin-like C2-type (immunoglobulin-like) domain in its extracellular portion.
Interleukin 6 receptor (IL6R) also known as CD126 is a type I cytokine receptor.
Interleukin 1 receptor, type II (IL-1R2) also known as CD121b is an interleukin receptor. IL1R2 also denotes its human gene.
Interleukin 1 receptor, type I (IL1R1) also known as CD121a, is an interleukin receptor. IL1R1 also denotes its human gene.
Interleukin 10 receptor, beta subunit is a subunit for the interleukin-10 receptor. IL10RB is its human gene.
Interleukin 11 receptor, alpha subunit is a subunit of the interleukin 11 receptor. IL11RA is its human gene.
Interleukin-36 gamma previously known as interleukin-1 family member 9 (IL1F9) is a protein that in humans is encoded by the IL36G gene.
Interleukin-17 receptor (IL-17R) is a cytokine receptor which binds interleukin 17A. Functional IL-17R is a heteromeric complex consisting of at least IL17RA and IL17RC.
The Interleukin-1 family is a group of 11 cytokines that plays a central role in the regulation of immune and inflammatory responses to infections or sterile insults.
Interleukin 22 receptor, alpha 1 is a protein that in humans is encoded by the IL22RA1 gene.
