Type II cytokine receptors

Immunoglobulin Type I cytokine receptors Type II cytokine receptors... 

Fig. 3.1 Families of cytokine receptors the cytokine receptors are classified into five major families immunoglobulin superfamily receptors, type I cytokine receptors, type II cytokine receptors, TNF-like receptors and chemokine receptors. The drawings illustrate their general biochemical structure (see Color Insert)...

The interferon receptor superfamily Cytokine receptor type II family Receptors for IFN-cx, -P, -y, IL-10... 

Studies have actually revealed two type I interferon receptor polypeptides. Sequence data from cloning studies place both in the class II cytokine receptor family. Both are transmembrane N-linked glycoproteins. Studies using isolated forms of each show that one polypeptide (called the a/p receptor) is capable of binding all type I interferons. The other one (the ap receptor) is specific for IFN-a-B (a specific member of the IFN-a family). Both receptors are present on most cell types. 

IL-IOR is a single-chain receptor. IL-IOR belongs to the class II cytokine receptor family that also includes the IFN receptors (IFNy and IFNap receptors). The extracellular region consists of two homologous fibronectin type III domains that are without the WSXWS motif characteristic of class I cytokine receptors. It is expressed on B cells, thymocytes, and other cellular lines such as mast cells and macrophages. Human IL-IOR mRNA is restricted mostly to hematopoietic cells and cell lines. ... 

The first specifically binds IFNaB (IFNaS, a variety of IFNa) and is known as the IFNaB receptor. The second bmds both IFNa and IFNp and is called the IFNa/j3 receptor. The IFNapR is a member of the class II cytokine receptor family, which also includes the IFNyR, IL-IOR, and tissue factor. The IFNa/ R is also a class II cytokine receptor and contains at least two components that interact with type I IFNs, It is not known if these two receptors are expressed independently on the cell surface or are associated with each other in an IFN receptor complex. The receptors are present on most types of cells. A soluble form of the IFNa/pR has been identified in human serum and urine. 

Glucocorticoids have been shown to inhibit gene transcription of other proteins involved in the inflammatory process, including the key inflammation mediators called cytokines (IL-1, IL3—6, IL8, GM-CSF, TNFa) (10,58,63—65). Steroids have been also shown to suppress the formation of cytokine receptors (10) dexamethasone, in particular, downregulates gene transcription of angiotensin II type 2 receptors (66). 

Some cytokine receptors are composed of a single transmembrane polypeptide (e.g. receptors for IL-8, -9 and -10). Many contain two polypeptide components (including the IL-3, -4, and -5 receptors), and a few contain three or more polypeptide components (e.g. the IL-2 receptor contains three polypeptide chains). In some instances a single cytokine may be capable of initiating signal transduction by binding two or more distinct receptors (e.g. IL-1 has two distinct receptors (types I and II), both of which are transmembrane glycoproteins). 

Lipids A first induce the expression of early inflammatory genes such as tumor necrosis factor- (TNF)-a, EL-1(3, type 2 TNF receptor, IP-10, D3, D8 and D2 genes [34]. Then further genes are activated such as other cytokines and receptors, adhesion molecules, acute-phase proteins, tissue factors, as well as the inducible NOS (NOS II). These cascades of events initiated by lipid A provoke in their target cells complex responses in vivo, whose relevance in the host response to tumor growth is reviewed below. 

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