Cytokine receptors are receptors that bind to

cytokine Cytokines are a broad and loose category of small proteins (~5–25 kDa) important in cell signaling. Cytokines are peptides and cannot cross the lipid bilayer of cells to enter the cytoplasm. Cytokines have been shown to be involved in autocrin ...

s. 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.

Classification

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 I cytokine receptor Type I cytokine receptors are transmembrane receptors expressed on the surface of cells that recognize and respond to cytokines with four α-helical strands. These receptors are also known under the name ''hemopoietin receptors'', and share a c ...

s, whose members have certain conserved motifs in their extracellular

amino-acid Amino acids are organic compounds that contain both amino and carboxylic acid functional groups. Although hundreds of amino acids exist in nature, by far the most important are the alpha-amino acids, which comprise proteins. Only 22 alpha ami ...

domain. The IL-2 receptor belongs to this chain, whose γ-chain (common to several other cytokines) deficiency is directly responsible for the x-linked form of

Severe Combined Immunodeficiency Severe combined immunodeficiency (SCID), also known as Swiss-type agammaglobulinemia, is a rare genetic disorder characterized by the disturbed development of functional T cells and B cells caused by numerous genetic mutations that result in diffe ...

(

X-SCID X-linked severe combined immunodeficiency (X-SCID) is an immunodeficiency disorder in which the body produces very few T cells and NK cells. In the absence of T cell help, B cells become defective. It is an X-linked recessive inheritance trait, ...

). * Type II cytokine receptors, whose members are receptors mainly for interferons. * Immunoglobulin (Ig) superfamily, which are ubiquitously present throughout several cells and tissues of the vertebrate body * Tumor necrosis factor receptor family, whose members share a cysteine-rich common extracellular binding domain, and includes several other non-cytokine ligands like receptors,

CD40 Cluster of differentiation 40, CD40 is a costimulatory protein found on antigen-presenting cells and is required for their activation. The binding of CD154 ( CD40L) on TH cells to CD40 activates antigen presenting cells and induces a variety of d ...

CD27 CD27 is a member of the tumor necrosis factor receptor superfamily. It is currently of interest to immunologists as a co-stimulatory immune checkpoint molecule, and is the target of an anti-cancer drug in clinical trials. Expression During mous ...

and

CD30 CD30, also known as TNFRSF8 ( TNF receptor superfamily member 8), is a cell membrane protein of the tumor necrosis factor receptor family and a tumor marker. Function This receptor is expressed by activated, but not by resting, T and B cel ...

, besides the ligands on which the family is named (TNF). *

Chemokine receptor Chemokine receptors are cytokine receptors found on the surface of certain cells that interact with a type of cytokine called a chemokine. There have been 20 distinct chemokine receptors discovered in humans. Each has a rhodopsin-like 7-trans ...

s, two of which acting as binding proteins for

HIV The human immunodeficiency viruses (HIV) are two species of ''Lentivirus'' (a subgroup of retrovirus) that infect humans. Over time, they cause acquired immunodeficiency syndrome (AIDS), a condition in which progressive failure of the immune ...

(

CXCR4 C-X-C chemokine receptor type 4 (CXCR-4) also known as fusin or CD184 (cluster of differentiation 184) is a protein that in humans is encoded by the ''CXCR4'' gene. The protein is a CXC chemokine receptor. Function CXCR-4 is an alpha-chemokin ...

and

CCR5 C-C chemokine receptor type 5, also known as CCR5 or CD195, is a protein on the surface of white blood cells that is involved in the immune system as it acts as a receptor for chemokines. In humans, the ''CCR5'' gene that encodes the CCR5 p ...

). They are

G protein coupled receptors G protein-coupled receptors (GPCRs), also known as seven-(pass)-transmembrane domain receptors, 7TM receptors, heptahelical receptors, serpentine receptors, and G protein-linked receptors (GPLR), form a large group of evolutionarily-related p ...

. * TGF-beta receptor family, which are Serine/threonine kinase receptors. Includes the TGF beta receptors

Comparison

Solubility

Cytokine receptors may be both membrane-bound and soluble. ''Soluble cytokine receptors'' are extremely common regulators of

function. Soluble cytokine receptors typically consist of the extracellular portions of membrane-bound receptors. .

References

External links

Cytokine-cytokine receptor interaction map
from

KEGG KEGG (Kyoto Encyclopedia of Genes and Genomes) is a collection of databases dealing with genomes, biological pathways, diseases, drugs, and chemical substances. KEGG is utilized for bioinformatics research and education, including data analysis i ...

* {{receptor-stub

Classification

Comparison

Solubility

See also

References

External links