Complement receptor type 1 (CR1) also known as C3b/C4b receptor or CD35 is a protein that in humans is encoded by the CR1 gene.
C5a is a protein fragment released from cleavage of complement component C5 by protease C5-convertase into C5a and C5b fragments. C5b is important in late events of the complement cascade, an orderly series of reactions which coordinates several basic defense mechanisms, including formation of the membrane attack complex (MAC), one of the most basic weapons of the innate immune system, formed as an automatic response to intrusions from foreign particles and microbial invaders. It essentially pokes microscopic pinholes in these foreign objects, causing loss of water and sometimes death. C5a, the other cleavage product of C5, acts as a highly inflammatory peptide, encouraging complement activation, formation of the MAC, attraction of innate immune cells, and histamine release involved in allergic responses. The origin of C5 is in the hepatocyte, but its synthesis can also be found in macrophages, where it may cause local increase of C5a. C5a is a chemotactic agent and an anaphylatoxin; it is essential in the innate immunity but it is also linked with the adaptive immunity. The increased production of C5a is connected with a number of inflammatory diseases.
The C3a receptor also known as complement component 3a receptor 1 (C3AR1) is a G protein-coupled receptor protein involved in the complement system.
Complement receptor type 2 (CR2), also known as complement C3d receptor, Epstein-Barr virus receptor, and CD21, is a protein that in humans is encoded by the CR2 gene.
Chemokine ligand 7 (CCL7) is a small cytokine that was previously called monocyte-chemotactic protein 3 (MCP3). CCL7 is a small protein that belongs to the CC chemokine family and is most closely related to CCL2.
C-C motif chemokine 11 also known as eosinophil chemotactic protein and eotaxin-1 is a protein that in humans is encoded by the CCL11 gene. This gene is encoded on three exons and is located on chromosome 17.
Chemokine ligand 21 (CCL21) is a small cytokine belonging to the CC chemokine family. This chemokine is also known as 6Ckine, exodus-2, and secondary lymphoid-tissue chemokine (SLC). CCL21 elicits its effects by binding to a cell surface chemokine receptor known as CCR7. The main function of CCL21 is to guide CCR7 expressing leukocytes to the secondary lymphoid organs, such as lymph nodes and Peyer´s patches.
CC chemokine receptors are integral membrane proteins that specifically bind and respond to cytokines of the CC 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. To date, ten true members of the CC chemokine receptor subfamily have been described. These are named CCR1 to CCR10 according to the IUIS/WHO Subcommittee on Chemokine Nomenclature.
Chemokine ligand 17 (CXCL17) is a small cytokine belonging to the CXC chemokine family that has been identified in humans and mice. CXCL17 attracts dendritic cells and monocytes and is regulated in tumors. It is also known as VEGF co-regulated chemokine 1 (VCC-1) and dendritic cell- and monocyte-attracting chemokine-like protein (DMC). This chemokine is constitutively expressed in the lung. The gene for human CXCL17 is located on chromosome 19.
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 ligand 19 (CCL19/ELC) and ligand 21 (CCL21). The ligands have similar affinity for the receptor, though CCL19 has been shown to induce internalisation of CCR7 and desensitisation of the cell to CCL19/CCL21 signals. CCR7 is a transmembrane protein with 7 transmembrane domains, which is coupled with heterotrimeric G proteins, which transduce the signal downstream through various signalling cascades. The main function of the receptor is to guide immune cells to immune organs by detecting specific chemokines, which these tissues secrete.
C-C chemokine receptor type 1 is a protein that in humans is encoded by the CCR1 gene.
Interleukin 1 receptor, type II (IL-1R2) also known as CD121b is an interleukin receptor. IL1R2 also denotes its human gene.
N-formyl peptide receptor 2 (FPR2) is a G-protein coupled receptor (GPCR) located on the surface of many cell types of various animal species. The human receptor protein is encoded by the FPR2 gene and is activated to regulate cell function by binding any one of a wide variety of ligands including not only certain N-Formylmethionine-containing oligopeptides such as N-Formylmethionine-leucyl-phenylalanine (FMLP) but also the polyunsaturated fatty acid metabolite of arachidonic acid, lipoxin A4 (LXA4). Because of its interaction with lipoxin A4, FPR2 is also commonly named the ALX/FPR2 or just ALX receptor.
N-Formylmethionyl-leucyl-phenylalanine is an N-formylated tripeptide and sometimes simply referred to as chemotactic peptide is a potent polymorphonuclear leukocyte (PMN) chemotactic factor and is also a macrophage activator.
Protease activated receptor 2 (PAR2) also known as coagulation factor II (thrombin) receptor-like 1 (F2RL1) or G-protein coupled receptor 11 (GPR11) is a protein that in humans is encoded by the F2RL1 gene. PAR2 modulates inflammatory responses, obesity, metabolism, cancers and acts as a sensor for proteolytic enzymes generated during infection. In humans, we can find PAR2 in the stratum granulosum layer of epidermal keratinocytes. Functional PAR2 is also expressed by several immune cells such as eosinophils, neutrophils, monocytes, macrophages, dendritic cells, mast cells and T cells.
N-formyl peptide receptor 3 (FPR3) is a receptor protein that in humans is encoded by the FPR3 gene.
Prostaglandin D2 receptor 2 (DP2 or CRTH2) is a human protein encoded by the PTGDR2 gene and GPR44. DP2 has also been designated as CD294 (cluster of differentiation 294). It is a member of the class of prostaglandin receptors which bind with and respond to various prostaglandins. DP2 along with Prostaglandin DP1 receptor are receptors for prostaglandin D2 (PGD2). Activation of DP2 by PGD2 or other cognate receptor ligands has been associated with certain physiological and pathological responses, particularly those associated with allergy and inflammation, in animal models and certain human diseases.
C5a anaphylatoxin chemotactic receptor 2 is a protein that in humans is encoded by the C5AR2 gene. It's a complement component G protein-coupled receptor, of class A (rhodopsin-like).
C3a is one of the proteins formed by the cleavage of complement component 3; the other is C3b. C3a is a 77 residue anaphylatoxin that binds to the C3a receptor (C3aR), a class A G protein-coupled receptor. It plays a large role in the immune response.
Formyl peptide receptor 1 is a cell surface receptor protein that in humans is encoded by the formyl peptide receptor 1 (FPR1) gene. This gene encodes a G protein-coupled receptor cell surface protein that binds and is activated by N-Formylmethionine-containing oligopeptides, particularly N-Formylmethionine-leucyl-phenylalanine (FMLP). FPR1 is prominently expressed by mammalian phagocytic and blood leukocyte cells where it functions to mediate these cells' responses to the N-formylmethionine-containing oligopeptides which are released by invading microorganisms and injured tissues. FPR1 directs these cells to sites of invading pathogens or disrupted tissues and then stimulates these cells to kill the pathogens or to remove tissue debris; as such, it is an important component of the innate immune system that operates in host defense and damage control.
