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Stem cell factor / KIT ligand (SCF) is a cytokine which binds CD117(c-Kit). SCF is also known as "steel factor" or "c-kit ligand". SCF exists in two forms, cell surface bound SCF and soluble (or free) SCF. Soluble SCF is produced by the cleavage of surface bound SCF by metalloproteases.
SCF is a growth factor important for the survival, proliferation, and differentiation of hematopoietic stem cells and other hematopoietic progenitor cells. One of its roles is to change the BFU-E (burst-forming unit-erythroid) cells, which are the earliest erythrocyte precursors in the erythrocytic series, into the CFU-E (colony-forming unit-erythroid).

Regulated upon Activation, Normal T-cell Expressed, and Secreted or RANTES is an 8 kDa protein classified as a chemotactic cytokine or chemokine. It has recently been renamed CCL5. RANTES is chemotactic for T cells, eosinophils and basophils and plays an active role in recruiting leukocytes into inflammatory sites. With the help of particular cytokines (i.e. IL-2 and IFN-?) that are released by T cells, RANTES also induces the proliferation and activation of certain natural killer (NK) cells to form CHAK (CC-Chemokine-activated killer) cells. It is also a HIV-suppressive factor released from CD8+ T cells. This chemokine has been localized to chromosome 17 in humans.

Chemokine (C-C motif) ligand 11 (CCL11) is a small cytokine belonging to the CC chemokine family that is also known as eotaxin. CCL11 selectively recruits eosinophils by inducing their chemotaxis, and therefore, is implicated in allergic responses. The effects of CCL11 are mediated by its binding to a G-protein-linked receptor known as a chemokine receptor. Chemokine receptors for which CCL11 is a ligand include CCR2, CCR3 and CCR5. The gene for human CCL11 (scya11) is encoded on three exons and is located on chromosome 17.

LYVE-1 has been identified as a major receptor for HA (extracellular matrix glycosaminoglycan hyaluronan) on the lymph vessel wall. The deduced amino acid sequence of LYVE-1 predicts a 322-residue type I integral membrane polypeptide 41% similar to the CD44 HA receptor with a 212-residue extracellular domain containing a single Link module the prototypic HA binding domain of the Link protein superfamily. Like CD44, the LYVE-1 molecule binds both soluble and immobilized HA. However, unlike CD44, the LYVE-1 molecule colocalizes with HA on the luminal face of the lymph vessel wall and is completely absent from blood vessels. Hence, LYVE-1 is the first lymph-specific HA receptor to be characterized and is a uniquely powerful marker for lymph vessels themselves.

CD27 belongs to the TNF-receptor superfamily. CD27 is necessary for initiation and long-term maintenance of T cell immunity. CD27 binds to ligand CD70, and has a crucial role in regulating B-cell activation and immunoglobulin synthesis. The CD27 receptor transduces signals which result in the activation of NF-kappaB and MAPK8/JNK. Adaptor proteins TRAF2 and TRAF5 mediate the signaling process of CD27. CD27-binding protein (SIVA), which is a proapoptotic protein, can bind to the CD27 receptor and is believed to have a significant role in the apoptosis induced by CD27.

Discoidin Domain Receptor Tyrosine Kinase 1 (DDR1) is a transmembrane glycoprotein which is a part of the discoidin-like domain containing subfamily of receptor tyrosine kinases. DDR1 functions as cell surface receptor for fibrillar collagen and regulates cell attachment to the extracellular matrix, remodeling of the extracellular matrix, cell migration, differentiation, survival and cell proliferation. DDR1 is expressed in epithelial cells, mainly in the kidney, lung, gastrointestinal tract, and brain and is significantly overexpressed in several human tumors.

Interleukin-3 is a pleiotropic cytokine produced primarily by activated T cells.
IL-3 is thought to function via specific cell surface receptors to stimulate the proliferation, differentiation and survival of haematopoietic cell lines. IL-3 has also been shown to affect the functional activity of a variety of other cell types including mast cells, eosinophils, megakaryocytes and basophils.

TRAF2 protein is related with transduce signals from members of the TNFR superfamily. TRAF2 is located in the cytoplasm binds to TRAF1, TRAF2, or TRAF3, thus inhibiting TRAF function by sequestering the TRAFs in a suppressed state in the cytoplasm. Overexpression of TANK inhibits TRAF2-mediated NF-Kappa-B activation signaled by CD40 and both TNF receptors and inhibits LMP1-mediated NF-kappa-B activation by blocking the association of TRAF2 with LMP1. TRAF2 is necessary for the cellular response to TNF-alpha by connecting upstream signalling molecules to the IKKs and p65.

Interleukin-1 alpha is a proinflammatory cytokine produced by a wide variety of cell types, including macrophages, osteoblasts, monocytes and hepatocytes. Circulating levels of are normally low and only rise after stimulation by agents such as those produced byinflammation, infection or microbial endotoxins. IL-1 alpha possesses a wide variety of biological activities and exerts its effects by binding to specific cell surface receptors.

HGF, also known as scatter factor (SF) and Hepatocyte growth factor, is secreted from mesenchymal cells, targets and acts mainly on epithelial and endothelial cells. The protein is a paracrine cellular growth, motility and morphogenic factor. HGF can also be part of haemopoietic progenitor cells and T cells. HGF has a crucial role in embryonic organ development, mainly in myogenesis. In adults HGF takes part in organ regeneration and wound healing.

CD93, is a receptor or else an element of a larger receptor complex for C1q, MBL2-mannose-binding lectin and SPA-pulmonary surfactant protein A. CD93 mediates the enhancement of phagocytosis in monocytes as well as macrophages upon interaction with soluble defense collagens. CD93 takes part in the intercellular adhesion. Furthermore, CD93 was expressed on (pre) plasmablasts/plasma cells, including long-lived plasma cells which demonstrated decreased cell cycle activity, high levels of isotype-switched Ig secretion, as well as modification of the transcriptional network. CD93 is vital for the maintenance of plasma cells in bone marrow niches.

Adiponectin is a recently discovered 244 amino acid protein, the product of the apM1 gene, which is physiologically active and specifically and highly expressed in adipose cells (Adipokine). The protein belongs to the soluble defense collagen super family; it has a collagen-like domain structurally homologous with collagen VIII and X and complement factor C1q-like globular domain. APM-1 forms homotrimers, which are the building blocks for higher order complexes found circulating in serum.

Since April 2012, cases of the Middle East Respiratory Syndrome Coronavirus (MERS-CoV) have been identified in various countries. Coronaviruses are the cause of the common cold, SARS (severe acute respiratory syndrome) and other severe illnesses with high mortality rates, all are classified into coronavirus family. MERS-CoV is a new type of SARS found in the coronavirus family causing severe pneumonia with sudden and serious respiratory illness with high mortality rates as well. Since January 27th 2015, the WHO has reported 956 human cases, including 351 deaths. More cases of the new coronavirus strain are expected. Like in other coronaviruses, large surface spike glycoprotein is a central structural protein of this virus; it is located above the virion surface to bind and enter into the target cell. Spike protein has 2 domains- S1 and S2. The S1 domain is responsible for cellular tropism and interaction with target cell, while the S2 domain is responsible for membrane fusion. The C-terminal of S1 domain contains a receptor binding domain, and is also a potential target for vaccine development and an antigen for diagnosis.

Interleukin-5 receptor subunit alpha (Il5ra) regulates the development and function of eosinophils. The Il5ra protein is a therapeutic target for hypereosinophilic diseases including allergic inflammations and asthma. Oct2 enhances antibody-secreting cell differentiation via regulation of Il5ra chain expression on activated B cells.

Integrins are heterodimeric integral membrane proteins composed of an alpha chain and a beta chain. This I-domain containing alpha integrin combines with the beta 2 chain (ITGB2) to form a leukocyte-specific integrin referred to as macrophage receptor 1 ('Mac-1'), or inactivated-C3b (iC3b) receptor 3 ('CR3'). The alpha M beta 2 integrin is important in the adherence of neutrophils and monocytes to stimulated endothelium, and also in the phagocytosis of complement coated particles. Integrin alpha-m/beta-2 is implicated in various adhesive interactions of monocytes, macrophages and granulocytes as well as in mediating the uptake of complement-coated particles. CD-11b is identical with cr-3, the receptor for the ic3b fragment of the third complement component. CD-11b probably recognizes the r-g-d peptide in c3b. Integrin alpha-m/beta-2 is also a receptor for fibrinogen, factor x and icam1. it recognizes p1 and p2 peptides of fibrinogen gamma chain.

TARC cDNA encodes a 94 amino acid precursor protein with a 23 amino acid residue signal peptide that is cleaved off to generate the 71 amino acid residue mature secreted protein. Along with CC chemokine family members, CCL-17 has approximately 24-29% amino acid sequence identity with RANTES, MIP-1a, MIP-1b, MCP-1, MCP-2, MCP-3 and I-309. TARC is expressed in thymus, and at a lower level in the lung, colon, and small intestine. TARC is in addition transiently expressed in stimulated peripheral blood mononuclear cells. Recombinant TARC has been shown to be chemotactic for T cell lines but not monocytes or neutrophils. CCL-17 was recently identified to be a specific functional ligand for CCR4, a receptor that is selectively expressed on T cells. CCL17 is one of quite a few Cys-Cys (CC) cytokine genes clustered on the q arm of chromosome 16. CCL17 shows chemotactic activity for T lymphocytes, but not monocytes or granulocytes. CCL17 binds to chemokine receptors CCR4 and CCR8. This chemokine plays important roles in T cell development in thymus as well as in trafficking and activation of mature T cells.

Macrophage Inflammatory Proteins (MIP) belong to the family of chemotactic cytokines known as chemokines. In humans, there are two major forms, MIP-1? and MIP-1? that are now officially named CCL3 and CCL4 respectively. Both are major factors produced by macrophages after they are stimulated with bacterial endotoxins. They activate human granulocytes (neutrophils, eosinophils and basophils) which can lead to acute neutrophilic inflammation. They also induce the synthesis and release of other pro-inflammatory cytokines such as interleukin 1 (IL-1), IL-6 and TNF-? from fibroblasts and macrophages. The genes for CCL3 and CCL4 are both located on human chromosome 17.

Chemokine (C-C motif) ligand 2 (CCL2) is a small cytokine belonging to the CC chemokine family that is also known as monocyte chemotactic protein-1 (MCP-1). It is found at the site of tooth eruption and bone degradation. In the bone, CCL2 is expressed by mature osteoclasts and osteoblasts and is under the control of nuclear factor ?B (NF?B). CCL2 recruits immune cells, such as monocytes, to sites of tissue injury and infection. This chemokine is produced as a protein precursor containing signal peptide of 23 amino acids and a mature peptide of 76 amino acids. It is a monomeric polypeptide, with a molecular weightof approximately 13kDa. As with many other CC chemokines, CCL2 is located on chromosome 17 in humans. The cell surface receptors that bind CCL2 are CCR2 and CCR5.

Chemokine (C-C motif) ligand 2 (CCL2) is a small cytokine belonging to the CC chemokine family that is also known as monocyte chemotactic protein-1 (MCP-1). It is found at the site of tooth eruption and bone degradation. In the bone, CCL2 is expressed by mature osteoclasts and osteoblasts and is under the control of nuclear factor ?B (NF?B). CCL2 recruits immune cells, such as monocytes, to sites of tissue injury and infection. This chemokine is produced as a protein precursor containing signal peptide of 23 amino acidsand a mature peptide of 76 amino acids. It is a monomeric polypeptide, with a molecular weight of approximately 13kDa. As with many other CC chemokines, CCL2 is located on chromosome 17 in humans. The cell surface receptors that bind CCL2 are CCR2 and CCR5.

TARC cDNA encodes a 94 amino acid precursor protein with a 23 amino acid residue signal peptide that is cleaved off to generate the 71 amino acid residue mature secreted protein. Along with CC chemokine family members, CCL-17 has approximately 24-29% amino acid sequence identity with RANTES, MIP-1a, MIP-1b, MCP-1, MCP-2, MCP-3 and I-309. TARC is expressed in thymus, and at a lower level in the lung, colon, and small intestine. TARC is in addition transiently expressed in stimulated peripheral blood mononuclear cells. Recombinant TARC has been shown to be chemotactic for T cell lines but not monocytes or neutrophils. CCL-17 was recently identified to be a specific functional ligand for CCR4, a receptor that is selectively expressed on T cells. CCL17 is one of quite a few Cys-Cys (CC) cytokine genes clustered on the q arm of chromosome 16. CCL17 shows chemotactic activity for T lymphocytes, but not monocytes or granulocytes. CCL17 binds to chemokine receptors CCR4 and CCR8. This chemokine plays important roles in T cell development in thymus as well as in trafficking and activation of mature T cells.

CD14 (also known lipopolysaccharide (LPS) receptor) is expressed strongly on monocytes and macrophage and weakly on the surface of neutrophils. CD14 is anchored to cells by linkage to glycosylphosphatidylinositol (GPI) and functions as a high affinity receptor for complexes of LPS and LPS binding protein (LBP). Soluble CD14, also binding to LPS, acts at physiological concentration as an LPS agonist and has, at higher concentrations, an LPS antagonizing effect in cell activation. CD14 has been shown to bind apoptotic cells.

Killer-cell immunoglobulin-like receptors (KIRs), are a family of cell surface glycoproteins found on Natural Killer (NK) Cells, which are important cells of the immune system. They control the killing function of these cells by interacting with MHC class I molecules, which are expressed on all cell types. This interaction allows them to identify virally infected cells or tumor cells that have a distinctive low level of Class I MHC on their surface. The majority of KIRs are inhibitory, which means that their recognition of MHC suppresses the cytotoxic activity of their NK cell. Only a limited number of KIRs have the capacity to activate cells.
The KIR genes are found in a cluster on chromosome 19q13.4 within the 1 Mb leukocyte receptor complex (LRC). KIR molecules are extremely polymorphic, meaning their gene sequences differ significantly between individuals, so that different individuals have different arrays/repertoires of KIR genes.
The KIR proteins are categorized by the number of extracellular immunoglobulin domains (2D or 3D) and by whether they have a long (L) or short (S) cytoplasmic domain. KIR proteins with the long cytoplasmic domain transduce inhibitory signals upon ligand binding via an immune tyrosine-based inhibitory motif (ITIM). Whereas KIR proteins with the short cytoplasmic domain lack the ITIM motif and instead associate with the TYRO protein tyrosine kinase binding protein to transduce activating signals.
The three Ig-domain from of inhibitory killer cell Ig-like receptor 1(KIR3DL1, NKB1, nkat3, p70KIR) is a NK cell receptor for polymorphic HLA-B determinant. KIR3DLl recognizes the Bw4 determinant defined by sequence motifs at positions 77-83 of the HLA-B heavy chain. The cytoplasmic tail of KIR, which contains two immunoreceptor tyrosine-based inhibition motifs (ITIMs), mediates inhibitory signal transduction that prevents killer cell-mediated cytotoxicity. A His-tag fusion protein of KIR3DL1 cytoplasmic tail (361-444aa) was overexpressed as insoluble protein aggregates (inclusion bodies).

CD160 antigen (CD160) is a human natural killer (NK)-cell-activating receptor which is also expressed on T-cell subsets. CD160 is a tumor-specific antigen known to mediate cellular activation signals in CLL, and is a novel target for therapeutic manipulation and monitoring of minimal residual disease. CD160 was identified as a T cell coinhibitory molecule which interacts with the herpesvirus entry mediator (HVEM) on antigen-presenting cells to deliver a potent inhibitory signal to CD4(+) T cells. CD160 expression is strongly associated with peripheral blood NK cells and CD8 T lymphocytes with cytolytic effector activity. CD160 is expressed on all intestinal intraepithelial lymphocytes. CD160 has a broad specificity for binding to both classical and nonclassical MHC class I molecules.