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Rhodopsin-like Receptors
Rhodopsin-like receptors are a family of proteins that comprise the largest group of G protein-coupled receptors. Scope G-protein-coupled receptors, GPCRs, constitute a vast protein family that encompasses a wide range of functions (including various autocrine, paracrine, and endocrine processes). They show considerable diversity at the sequence level, on the basis of which they can be separated into distinct groups. GPCRs are usually described as "superfamily" because they embrace a group of families for which there are indications of evolutionary relationship, but between which there is no statistically significant similarity in sequence. The currently known superfamily members include the rhodopsin-like GPCRs (this family), the secretin-like GPCRs, the cAMP receptors, the fungal mating pheromone receptors, and the metabotropic glutamate receptor family. There is a specialised database for GPCRs. Function The rhodopsin-like GPCRs themselves represent a widespread prote ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Protein Family
A protein family is a group of evolutionarily related proteins. In many cases, a protein family has a corresponding gene family, in which each gene encodes a corresponding protein with a 1:1 relationship. The term "protein family" should not be confused with family as it is used in taxonomy. Proteins in a family descend from a common ancestor and typically have similar three-dimensional structures, functions, and significant sequence similarity. The most important of these is sequence similarity (usually amino-acid sequence), since it is the strictest indicator of homology and therefore the clearest indicator of common ancestry. A fairly well developed framework exists for evaluating the significance of similarity between a group of sequences using sequence alignment methods. Proteins that do not share a common ancestor are very unlikely to show statistically significant sequence similarity, making sequence alignment a powerful tool for identifying the members of protein famil ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
CX3CR1
CX3C motif chemokine receptor 1 (CX3CR1), also known as the fractalkine receptor or G-protein coupled receptor 13 (GPR13), is a transmembrane protein of the G protein-coupled receptor 1 (GPCR1) family and the only known member of the CX3C chemokine receptor subfamily. As the name suggests, this receptor binds the inflammatory chemokine CX3CL1 (also called neurotactin in mice or fractalkine in humans). This endogenous ligand solely binds to CX3CR1 receptor. Interaction of CX3CR1 with CX3CL1 can mediate migration, adhesion and retention of leukocytes, because Fractalkine exists as membrane-anchored protein (mCX3CL1) as well as cleaved soluble molecule (sCX3CL1) due to proteolysis by metalloproteinases (MPPs). The shedded form carries out typical function of conventional chemokines, the chemotaxis, while the membrane-bound protein behaves as adhesion molecule for facilitation of diapedesis. Both partners of CX3CL1-CX3CR1 axis are present on numerous cell types from hematopoietic ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Interleukin-8
Interleukin 8 (IL-8 or chemokine (C-X-C motif) ligand 8, CXCL8) is a chemokine produced by macrophages and other cell types such as epithelial cells, airway smooth muscle cells and endothelial cells. Endothelial cells store IL-8 in their storage vesicles, the Weibel-Palade bodies. In humans, the interleukin-8 protein is encoded by the ''CXCL8'' gene. IL-8 is initially produced as a precursor peptide of 99 amino acids which then undergoes cleavage to create several active IL-8 isoforms. In culture, a 72 amino acid peptide is the major form secreted by macrophages. There are many receptors on the surface membrane capable of binding IL-8; the most frequently studied types are the G protein-coupled serpentine receptors CXCR1 and CXCR2. Expression and affinity for IL-8 differs between the two receptors (CXCR1 > CXCR2). Through a chain of biochemical reactions, IL-8 is secreted and is an important mediator of the immune reaction in the innate immune system response. Function IL- ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
CXCR7
Atypical chemokine receptor 3 also known as C-X-C chemokine receptor type 7 (CXCR-7) and G-protein coupled receptor 159 (GPR159) is a protein that in humans is encoded by the ''ACKR3'' gene. This gene encodes a member of the G protein-coupled receptor family. This protein was earlier thought to be a receptor for vasoactive intestinal peptide (VIP) and was considered to be an orphan receptor. It is now classified as a chemokine receptor able to bind the chemokines CXCL12/SDF-1 and CXCL11. The protein is also a coreceptor for human immunodeficiency viruses (HIV). Translocations involving this gene and HMGA2 on chromosome 12 have been observed in lipomas. Alternatively spliced transcript variants encoding the same protein isoform have been found for this gene. Whereas some reports claim that the receptor induces signaling following ligand binding, recent findings in zebrafish suggest that CXCR7 functions primarily by sequestering the chemokine CXCL12. Another study has provided evide ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
CXCR6
C-X-C chemokine receptor type 6 is a protein that in humans is encoded by the ''CXCR6'' gene. CXCR6 has also recently been designated CD186 (cluster of differentiation The cluster of differentiation (also known as cluster of designation or classification determinant and often abbreviated as CD) is a protocol used for the identification and investigation of cell surface molecules providing targets for immunophen ... 186). CXCR6 has been identified as an entry coreceptor used by HIV-1 and SIV to enter target cells, in conjunction with CD4. It is a minor coreceptor for HIV-1, nearly all strains of which use CCR5 and/or CXCR4. Most SIV strains can use CXCR6 and recent evidence suggests that in monkeys that serve as the natural hosts of SIV, CXCR6 may be a major coreceptor. CXCR6 was previously known as "Bonzo" and "STRL33" in the HIV/SIV field. References Further reading * * * * * * * * * * * * * * * External links * * Clusters of differentiati ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
CXCR5
C-X-C chemokine receptor type 5 (CXC-R5) also known as CD185 (cluster of differentiation 185) or Burkitt lymphoma receptor 1 (BLR1) is a G protein-coupled seven transmembrane receptor for chemokine CXCL13 (also known as BLC) and belongs to the CXC chemokine receptor family. It enables T cells to migrate to lymph node and the B cell zones. In humans, the CXC-R5 protein is encoded by the ''CXCR5'' gene. Tissue distribution and function The ''BLR1'' / ''CXCR5'' gene is specifically expressed in Burkitt's lymphoma and lymphatic tissues, such as follicles in lymph nodes as well as in spleen. The gene plays an essential role in B cell migration. Through CXCL13 secretions B cells are able to locate the lymph node. Additionally, some recent studies have suggested that CXCL13, through CXCR5, is capable of recruiting hematopoietic precursor cells (CD3− CD4+) which would cause the development of lymph nodes and Peyer's Patches. Other studies highlight the role of CXCR5 in T cells, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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-chemokine receptor specific for stromal-derived-factor-1 ( SDF-1 also called CXCL12), a molecule endowed with potent chemotactic activity for lymphocytes. CXCR4 is one of several chemokine co-receptors that HIV can use to infect CD4+ T cells. HIV isolates that use CXCR4 are traditionally known as T-cell tropic isolates. Typically, these viruses are found late in infection. It is unclear as to whether the emergence of CXCR4-using HIV is a consequence or a cause of immunodeficiency. CXCR4 is upregulated during the implantation window in natural and hormone replacement therapy cycles in the endometrium, producing, in presence of a human blastocyst, a surface polarization of the CXCR4 receptors suggesting that this receptor is implicated in t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
CXCR3
Chemokine receptor CXCR3 is a Gαi protein-coupled receptor in the CXC chemokine receptor family. Other names for CXCR3 are G protein-coupled receptor 9 (GPR9) and CD183. There are three isoforms of CXCR3 in humans: CXCR3-A, CXCR3-B and chemokine receptor 3-alternative (CXCR3-alt). CXCR3-A binds to the CXC chemokines CXCL9 (MIG), CXCL10 (IP-10), and CXCL11 (I-TAC) whereas CXCR3-B can also bind to CXCL4 in addition to CXCL9, CXCL10, and CXCL11. Expression CXCR3 is expressed primarily on activated T lymphocytes and NK cells, and some epithelial cells. CXCR3 and CCR5 are preferentially expressed on Th1 cells, whereas Th2 cells favor the expression of CCR3 and CCR4. CXCR3 ligands that attract Th1 cells can concomitantly block the migration of Th2 cells in response to CCR3 ligands, thus enhancing the polarization of effector T cell recruitment. Signal transduction Binding of CXCL9, CXCL10, and CXCL11 to CXCR3 is able to elicit increases in intracellular Ca2++ levels a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
CXC Chemokine Receptors
CXC chemokine receptors are integral membrane proteins that specifically bind and respond to cytokines of the CXC chemokine family. They represent one subfamily of chemokine receptors, a large family of G protein-linked receptors that are known as seven transmembrane (7-TM) proteins, since they span the cell membrane seven times. There are currently six known CXC chemokine receptors in mammals, named CXCR1 through CXCR6. CXCR1 and CXCR2 CXCR1 and CXCR2 are closely related receptors that recognize CXC chemokines that possess an E-L-R amino acid motif immediately adjacent to their CXC motif. CXCL8 (otherwise known as interleukin-8) and CXCL6 can both bind CXCR1 in humans, while all other ELR-positive chemokines, such as CXCL1 to CXCL7 bind only CXCR2. They are both expressed on the surface of neutrophils in mammals. CXCR3 CXCR3 is expressed predominantly on T cells (T lymphocytes), and also on other lymphocytes B_cell.html"_;"title="ome_B_cell">ome_B_cells_(B_lympho ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
CCR10
C-C chemokine receptor type 10 is a protein that in humans is encoded by the ''CCR10'' gene. Function Chemokines are a group of small (approximately 8 to 14 kD), mostly basic, structurally related molecules that regulate cell trafficking of various types of leukocytes through interactions with a subset of 7-transmembrane, G protein-coupled receptors. Chemokines also play fundamental roles in the development, homeostasis, and function of the immune system, and they have effects on cells of the central nervous system as well as on endothelial cells involved in angiogenesis or angiostasis. Chemokines are divided into 2 major subfamilies, CXC and CC, based on the arrangement of the first 2 of the 4 conserved cysteine residues; the 2 cysteines are separated by a single amino acid in CXC chemokines and are adjacent in CC chemokines. CCR10 is a chemokine receptor. Its ligands are CCL27 and CCL28. This receptor is normally expressed by melanocytes, plasma cells and skin-homing T cell ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
CCR9
C-C chemokine receptor type 9 is a protein that in humans is encoded by the ''CCR9'' gene. CCR9 has also recently been designated CDw199 (cluster of differentiation w199). The protein encoded by this gene is a member of the beta chemokine receptor family. It is predicted to be a seven transmembrane protein similar to G protein-coupled receptors. Chemokines and their receptors are key regulators of thymocyte migration and maturation in normal and inflammatory conditions. The specific ligand of this receptor is CCL25 Chemokine (C-C motif) ligand 25 (CCL25) is a small cytokine belonging to the CC chemokine family that is also known as TECK (Thymus-Expressed Chemokine). CCL25 is believed to play a role in the development of T-cells. It is chemotactic for thymo .... It has been found that this gene is differentially expressed by T lymphocytes of small intestine and colon, suggested a role in thymocyte recruitment and development that may permit functional specialization of immune r ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
CCR7
C-C chemokine receptor type 7 is a protein that in humans is encoded by the ''CCR7'' gene. Two ligands have been identified for this receptor: the chemokines (C-C motif) ligand 19 (CCL19/ELC) and (C-C motif) ligand 21 (CCL21). CCR7 has also recently been designated CD197 (cluster of differentiation 197). Function The protein encoded by this gene is a member of the G protein-coupled receptor family. This receptor was identified as a gene induced by the Epstein–Barr virus (EBV), and is thought to be a mediator of EBV effects on B lymphocytes. This receptor is expressed in various lymphoid tissues and activates B and T lymphocytes. CCR7 has been shown to stimulate dendritic cell maturation. CCR7 is also involved in homing of T cells to various secondary lymphoid organs such as lymph nodes and the spleen as well as trafficking of T cells within the spleen. Activation of dendritic cells in peripheral tissues induces CCR7 expression on the cell's surface, which recognize CCL19 and ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
