Chemokines are a family of pro-inflammatory activation-inducible cytokines, or small protein signals secreted by cells. Chemokines induce directed chemotaxis in nearby responsive cells, hence the name chemotactic cytokines. Former names for these proteins include SIS family of cytokines, SIG family of cytokines, SCY family of cytokines, Platelet factor-4 superfamily or intercrines. Cytokines are small protein molecules that are the core of communication between immune system cells, and even between immune system cells and cells belonging to other tissue types. ... A representation of the 3D structure of myoglobin, showing coloured alpha helices. ... Cells in culture, stained for keratin (red) and DNA (green). ... Chemotaxis is a kind of taxis, in which bodily cells, bacteria, and other single-cell or multicellular organisms direct their movements according to certain chemicals in their environment. ...

Characteristics

All chemokines have molecular masses of between 8 and 10 kDa and are approximately 20-50% identical. That is, they share 20-50% gene sequence and amino acid sequence homology with each other. Their receptors are all integral membrane proteins containing seven membrane-spanning helices which are coupled to G proteins. The proteins also share common tertiary structures. All chemokines possess a number of conserved cysteine residues involved in intramolecular disulfide bond formation. The molecular mass (abbreviated MM) of a substance, called molecular weight and abbreviated as MW, is the mass of one molecule of that substance, relative to the unified atomic mass unit u (equal to 1/12 the mass of one atom of carbon-12). ... Possible meanings: Kachin Defense Army Kentucky Distillers Association Kongsberg Defence & Aerospace This page expands a three-character combination which might be any or all of: an abbreviation, an acronym, an initialism, a word in English, or a word in another language. ... This stylistic schematic diagram shows a gene in relation to the double helix structure of DNA and to a chromosome (right). ... A protein primary structure is a chain of amino acids. ... An amino acid residue is what is left of an amino acid once a molecule of water has been lost (an H+ from the nitrogenous side and an OH- from the carboxylic side) in the formation of a peptide bond. ... A protein primary structure is a chain of amino acids. ... In biochemistry, a receptor is a protein on the cell membrane or within the cytoplasm or cell nucleus that binds to a specific molecule (a ligand), such as a neurotransmitter, hormone, or other substance, and initiates the cellular response to the ligand. ... G-proteins, short for guanine nucleotide binding proteins, are a family of proteins involved in second messenger cascades. ... In biochemistry, the tertiary structure of a protein is its overall shape. ... Cysteine is a naturally occurring amino acid which has a thiol group and is found in most proteins, though only in small quantities. ... A disulfide bond (SS-bond), also called a disulfide bridge, is a strong covalent bond between two sulfhydryl (-SH) groups. ...

Function

Chemokines are released from a wide variety of cells in response to bacterial infection, viruses and agents that cause physical damage such as silica or the urate crystals that occur in gout. They function mainly as chemoattractants for leukocytes, recruiting monocytes, neutrophils and other effector cells from the blood to sites of infection or damage. They can be released by many different cell types and serve to guide cells involved in innate immunity and also the lymphocytes in adaptive immunity. Some chemokines also have roles in the development of lymphocytes, migration and angiogenesis (the growth of new blood vessels). Subgroups Actinobacteria Aquificae Bacteroidetes/Chlorobi Chlamydiae/Verrucomicrobia Chloroflexi Chrysiogenetes Cyanobacteria Deferribacteres Deinococcus-Thermus Dictyoglomi Fibrobacteres/Acidobacteria Firmicutes Fusobacteria Gemmatimonadetes Nitrospirae Planctomycetes Proteobacteria Spirochaetes Thermodesulfobacteria Thermomicrobia Thermotogae Bacteria (singular: bacterium) are a major group of living organisms. ... Groups I: dsDNA viruses II: ssDNA viruses III: dsRNA viruses IV: (+)ssRNA viruses V: (-)ssRNA viruses VI: ssRNA-RT viruses VII: dsDNA-RT viruses A virus (Latin, poison) is a submicroscopic particle that can infect the cells of a biological organism. ... The chemical compound silicon dioxide, also known as silica, is the oxide of silicon, chemical formula SiO2. ... White Blood Cells is also the name of a White Stripes album. ... Monocyte A monocyte is a leukocyte, part of the human bodys immune system that protect against blood-borne pathogens and move quickly to sites of infection in the tissues. ... Neutrophil granulocytes (commonly referred to as neutrophils) are a class of white blood cells and are part of the immune system. ... Human blood smear: a - erythrocytes; b - neutrophil; c - eosinophil; d - lymphocyte. ... An infection is the detrimental colonization of a host organism by a foreign species. ... Innate immunity is immunity that the body possesses naturally, as opposed to adaptive immunity. ... Angiogenesis is the physiological process involving the growth of new blood vessels from pre-existing vessels. ...

Types

Members of the chemokine family fall mostly into two broad groups-CC chemokines (or β-chemokines) with two adjacent cysteines near the amino terminus of the protein, and CXC chemokines (or α-chemokines) in which the cysteines are separated by an amino acid. The two groups of chemokines act on different receptors. Receptor may refer to: In telecommunication, a receiver. ...

CC chemokines (β)

CC chemokines bind to CC chemokine receptors, of which nine have been discovered to date, designated CCR1-9. CXC chemokines bind to CXC chemokine receptors, of which five have been discovered to date, designated CXCR1-5. These receptors are expressed on the surface of different cell types.

CC chemokines induce the migration of monocytes and other cell types such as NK cells and dendritic cells. An example of a CC chemokine is monocyte chemoattractant protein-1 (MCP-1) which induces monocytes to leave the bloodstream and enter the surrounding tissue, becoming tissue macrophages. Natural killer cells (NK) are a type of lymphocyte (a white blood cell) and a component of nonspecific immune defense. ... Dendritic cells (DC) are immune cells and form part of the mammal immune system. ... Monocyte chemoattractant protein-1 (MCP-1) is an example of a CC chemokine which induces monocytes to leave the bloodstream and enter the surrounding tissue, becoming tissue macrophages. ...

CCR5, or chemokine (C-C motif) receptor 5, binds RANTES. CCR5, short for chemokine (C-C motif) receptor 5, is a chemokine receptor. ... Regulated upon activation, normal T-cell expressed, and presumably secreted or RANTES is an 8kDa protein classified as a chemotactic cytokine or chemokine. ...

CXC chemokines (α)

CXC chemokines which have a specific amino acid sequence (or motif) of Glutamic acid-Leucine-Arginine (or ELR for short) immediately before the first cysteine induce the migration of neutrophils. An example of this is interleukin-8 (IL-8) which induces neutrophils to leave the bloodstream and enter into the surrounding tissue. Other CXC chemokines which lack the ELR motif, such as the B-lymphocyte chemokine are chemoattractant for lymphocytes. Glutamic acid (Glu), also referred to as glutamate (the anion), is one of the 20 proteinogenic amino acids. ... Leucine is one of the 20 most common amino acids and coded for by DNA. It is isomeric with isoleucine. ... Arginine (Arg) is an α-amino acid. ... Interleukin-8 (IL-8) is a chemokine produced by macrophages and other cell types such as epithelial cells. ...

CXCR4 is involved in HIV infection. CXCR4, also called fusin, is an alpha-chemokine receptor specific for stromal-derived-factor-1 (SDF-1). ... Human immunodeficiency virus (commonly known as HIV, and formerly known as HTLV-III and lymphadenopathy-associated virus) is a retrovirus that is the cause of the disease known as AIDS, or Acquired Immunodeficiency Syndrome, a syndrome where the immune system begins to fail, leading to many life-threatening opportunistic infections. ...

C chemokines (γ)

The only known chemokine with only one cysteine is lymphotactin and is thought to attract T cell precursors to the thymus. Its family is known as the C chemokines (or γ-chemokines). In human anatomy, the thymus is a ductless gland located in the upper anterior portion of the chest cavity. ...

CX₃C chemokines (δ)

A fourth group has also been discovered and members have three amino acids between the two cysteines and is termed CX₃C chemokine (or δ-chemokines). The only CX₃C chemokine discovered to date is called fractalkine (or CX₃CL1). It is both secreted and tethered to the surface of the cell that expresses it, thereby serving as both a chemoattractant and as an adhesion molecule. Cell Adhesion Molecules (CAMs) are proteins located on the cell surface involved with the binding with other cells or with the extracellular matrix (ECM) in the process called cell adhesion. ...

Infection control

The discovery that the β chemokines RANTES, MIP (Macrophage Inflammatory Proteins) 1α and 1β (now known as CCL5, CCL3 and CCL4 respectively) suppress HIV-1 provided the initial connection and indicated that these molecules might control infection as part of immune responses in vivo.^[1] The association of chemokine production with antigen-induced proliferative responses, more favorable clinical status in HIV infection, as well as with an uninfected status in subjects at risk for infection suggests a positive role for these molecules in controlling the natural course of HIV infection.^[2] Regulated upon activation, normal T-cell expressed, and presumably secreted or RANTES is an 8kDa protein classified as a chemotactic cytokine or chemokine. ... Macrophage Inflammatory Proteins (MIP) belong to the family of chemotactic cytokines known as chemokines. ... Human immunodeficiency virus (commonly known as HIV, and formerly known as HTLV-III and lymphadenopathy-associated virus) is a retrovirus that is the cause of the disease known as AIDS, or Acquired Immunodeficiency Syndrome, a syndrome where the immune system begins to fail, leading to many life-threatening opportunistic infections. ... Human immunodeficiency virus (commonly known as HIV, and formerly known as HTLV-III and lymphadenopathy-associated virus) is a retrovirus that is the cause of the disease known as AIDS, or Acquired Immunodeficiency Syndrome, a syndrome where the immune system begins to fail, leading to many life-threatening opportunistic infections. ...

External links

• IUPHAR GPCR Database - Chemokine Receptors
• List of chemokines and their receptors
• Suppression of HIV by chemokines

Notes

1. ↑  Cocchi F, DeVico AL, Garzino-Demo A, Arya SK, Gallo RC, and Lusso P (October 1995). "Identification of RANTES, MIP-1a, and MIP-1b as the major HIV-suppressive factor produced by CD8+ T cells". Science 270: 1811-1815.
2. ↑  Alfredo Garzino-Demo, Ronald B. Moss, Joseph B. Margolick, Farley Cleghorn, Anne Sill, William A. Blattner, Fiorenza Cocchi, Dennis J. Carlo, Anthony L. DeVico, and Robert C. Gallo (October 1999). "Spontaneous and antigen-induced production of HIV-inhibitory β-chemokines are associated with AIDS-free status". Proc Natl Acad Sci U S A 96 (21): 11986–11991.

Dr. Robert C. Gallo Robert Charles Gallo (born March 23, 1937) is a U.S. biomedical researcher. ... Dr. Robert C. Gallo Robert Charles Gallo (born March 23, 1937) is a U.S. biomedical researcher. ...

See also

• Paracrine signalling