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A natural cytotoxicity receptor (NCR) NKp46 has been shown to represent a novel NK cell-specific molecule involved in human NK cell activation. The natural cytotoxicity receptors (NCRs) are a recently characterized family of Ig-like activation receptors that appear to be major triggering receptors in tumor cell recognition. The three known NCRs include NKp46 and NKp30, which are expressed on circulating NKcells, and NKp44, which is expressed only on activating NK cells. NKp46 has been implicated in NK cell-mediated lysis of several autologous tumor cells, pathogen-infected cell lines and mononuclear phagocytes infected with an intracellular bacterium. The Lysis of tumor cells by NK-cells involves recognition by NKp46 of heparan sulfate moieties of membrane heparan sulfate proteoglycans. Furthermore, NKp46 is a surface receptor involved in NK-cell cell death by apoptosis. NKp46 has two extracellular Ig-like domains followed by a ~40 residue stalk region, a type I transmembrane domain, and a short cytoplasmic tail. The extracellular Ig-like domain of NKp46 (22-255aa) is purified by FPLC gel-filtration chromatography, after refolding of the isolated inclusion bodies in a redox buffer. In addition, engagement of the antigen with the monoclonal antibody stimulates intracellular calcium levels and the synthesis of cytokines. CD59 is an NKp46 coreceptor (by physical association) together they activate cytotoxicity of human NK-cells, their engagement results in tyrosine phosphorylation of CD3-zeta chains associated with NKp46. Reduced cell surface expression of NKp46 and other NK-cell receptors is linked to the impaired NK-cell cytolytic function in viremic HIV-1 infection.

NCR2 (NKp44) belongs to the natural cytotoxicity receptor (NCR) family which is expressed on activated human NK cells. NKp44 exhibits a single extracellular Ig-like V domain and a transmembrane portion containing the charged residue (Lysine), possibly involved in the association with KARAP/DAP12 molecules. The gene coding for NKp44 maps on human chromosome 6p21.1.

NKp30 is a natural cytotoxicity receptor (NCR) that may assist NK cells in the lysis of tumor cells. NKp30 interacts with CD3-zeta (CD247), a T-cell receptor. A single nucleotide polymorphism in the 5'' untranslated region of the NKp30 gene has been linked to mild malaria susceptibility.

A natural cytotoxicity receptor (NCR) NKp46 has been shown to represent a novel NK cell-specific molecule involved in human NK cell activation. The natural cytotoxicity receptors (NCRs) are a recently characterized family of Ig-like activation receptors that appear to be major triggering receptors in tumor cell recognition. The three known NCRs include NKp46 and NKp30, which are expressed on circulating NKcells, and NKp44, which is expressed only on activating NK cells. NKp46 has been implicated in NK cell-mediated lysis of several autologous tumor cells, pathogen-infected cell lines and mononuclear phagocytes infected with an intracellular bacterium. The Lysis of tumor cells by NK-cells involves recognition by NKp46 of heparan sulfate moieties of membrane heparan sulfate proteoglycans. Furthermore, NKp46 is a surface receptor involved in NK-cell cell death by apoptosis. NKp46 has two extracellular Ig-like domains followed by a ~40 residue stalk region, a type I transmembrane domain, and a short cytoplasmic tail. The extracellular Ig-like domain of NKp46 (22-255aa) is purified by FPLC gel-filtration chromatography, after refolding of the isolated inclusion bodies in a redox buffer. In addition, engagement of the antigen with the monoclonal antibody stimulates intracellular calcium levels and the synthesis of cytokines. CD59 is an NKp46 coreceptor (by physical association) together they activate cytotoxicity of human NK-cells, their engagement results in tyrosine phosphorylation of CD3-zeta chains associated with NKp46. Reduced cell surface expression of NKp46 and other NK-cell receptors is linked to the impaired NK-cell cytolytic function in viremic HIV-1 infection.

Cytotoxicity Triggering Receptor 3 also known as NCR3 is a natural cytotoxicity receptor (NCR) which assists NK cells in the lysis of tumor cells. Moreover, NCR3 interacts with CD3-zeta (CD247), a T-cell receptor. A single nucleotide polymorphism in the 5' untranslated region of NCR3 has been related with mild malaria suceptibility. Three transcript variants encoding various isoforms have been found for this gene.

C-type Lectin Domain Family 1 Member B, also known as CLEC1B. NK-Natural killer cells express multiple calcium-dependent (C-type) lectin-like receptors, for instance CD94 (KLRD1; MIM 602894) and NKG2D (KLRC4; MIM 602893), which interact with major histocompatibility complex class I molecules and either inhibit or else activate cytotoxicity and cytokine secretion. CLEC1B is a C-type lectin-like receptor which is expressed in myeloid cells as well as in NK cells.

LAIR1 is a glycoprotein expressed on the surface of the majority of human peripheral blood mononuclear leukocytes including T cells, B cells, NK cells, macrophages and dendritic cells. LAIR-1 functions as an inhibitory receptor in NK cells, T cells and B cells. Inhibitory receptors control the immune response to prevent lysis of cells recognized as self. Lair1 consists of a leader sequence, extracellular domain, transmembrane domain, cytoplasmic region.LAIR1 is a member of both the immunoglobulin superfamily and the leukocyte-associated inhibitory receptor family. LAIR1 maps to a region of 19q13.4 labeled the leukocyte receptor cluster, which contains at least 29 genes encoding leukocyte-expressed receptors of the immunoglobulin superfamily.

C-type lectin domain family 7 member A 1 or CLEC7A is a protein, that in the innate immune system, acts against fungal pathogens. CLEC7A can be found in the immune system response cells such as monocytes, macrophages & neutrophils, or in dendritic and T cells. The protein is enhanced by macrophages by using GM-CSF, IL-4, or IL-13, or diminishes by dexamethasone, IL-10 and LPS.

Hepatitis A virus cellular receptor 1 (HAVCR1) is a membrane receptor for both human hepatitis A virus (HHAV) and TIMD4. HAVCR1 is a type I trans-membrane structural glycoprotein located in the renal proximal tubule epithelial cells. HAVCR1 protein may be involved in the control of asthma and allergic diseases. The reference genome represents an allele which retains a MTTVP amino acid segment that presents defense against atopy in HHAV seropositive individuals.

LAIR1 is a glycoprotein (~32kDa) expressed on the surface of the majority of human peripheral blood mononuclear leukocytes including T cells, B cells, NK cells, macrophages and dendritic cells. LAIR-1 functions as an inhibitory receptor in NK cells, T cells and B cells. Inhibitory receptors control the immune response to prevent lysis of cells recognized as self. Lair1 consists of a leader sequence, extracellular domain, transmembrane domain, cytoplasmic region.
LAIR1 is a member of both the immunoglobulin superfamily and the leukocyte-associated inhibitory receptor family. LAIR1 maps to a region of 19q13.4 labeled the leukocyte receptor cluster, which contains at least 29 genes encoding leukocyte-expressed receptors of the immunoglobulin superfamily.

CD33 is putative adhesion molecule of myelomonocytic-derived cells which mediates sialic-acid dependent binding to cells. CD33 prefers to bind to alpha-2,6-linked sialic acid. The sialic acid recognition site is masked by cis interactions with sialic acids on the same cell surface. In the immune response, CD33 perform as an inhibitory receptor upon ligand induced tyrosine phosphorylation by recruiting cytoplasmic phosphatases through their SH2 domains which block signal transduction through dephosphorylation of signaling molecules. In addition, CD33 induces apoptosis in acute myeloid leukemia.

CD207 (C-type lectin domain family 4 member K) is expressed in Langerhans cells which are immature dendritic cells of the epidermis and mucosa. Moreover, CD207 is expressed in several other dendritic cell types including dermal CD103+ DCs and splenic CD8+ DCs. Langerin is localized in the Birbeck granules, the organelles present in the cytoplasm of Langerhans cells and comprised of superimposed and zippered membranes. CD207 is a C-type lectin with mannose binding specificity, and it has been suggested that mannose binding by the CD207 protein leads to internalization of antigen into Birbeck granules thus providing access to a nonclassical antigen-processing pathway.

Thymic Stromal Lymphopoietin Receptor (TSLPR) is a member of the type I cytokine receptor family. TSLPR alongside the interleukin 7 receptor (IL7R) activate STAT3, STAT5, and JAK2 pathways, which is regulated processes such as cell proliferation and development of the hematopoietic system. Two transcript variants encoding dissimilar isoforms have been found for this gene. TSLPR is expressed in heart, skeletal muscle, kidney and adult and fetal liver.

Galectin 3, or LGALS3, is a protein which belongs to the animal lectins family, that binds betagalactoside residues selectively. LGALS3 is originated and leaves cells through ectocytosis. The protein is capable of inhibition apoptosis and the development of cancer. Galectin 3 is found in epithelial tissues in organisms, it can be located in dendritic cells, Kupffer cells, macrophages etc. LGALS3 levels elevated when inflammation is generating, cell proliferation, trans-activation by viral proteins and cell differentiation.

C-type Lectin Domain Family 4, Member M (CLEC4M) is a type II integral membrane proteinand A pathogen-recognition receptor which takes part in peripheral immune surveillance in liver. CLEC4M mediates the endocytosis of pathogens which than degraded in lysosomal compartments. CLEC4M is a receptor for ICAM3, binding to mannose-like carbohydrates and also recognizes various evolutionarily divergent pathogens with a large impact on public health, including tuberculosis mycobacteria, and viruses which among them are Ebola, hepatitis C,influenza A, HIV-1, West Nile virus and the SARS-CoV acute respiratory syndrome coronavirus.

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.

Sialic Acid Binding Ig Like Lectin 5, also known as SIGLEC5 is a member of the immunoglobulin superfamily and SIGLEC family. SIGLEC5 contains of 2 Ig-like C2-type domains and 1 Ig-like V-type domain. In addition, SIGLEC5 is expressed by monocytic/myeloid lineage cells. SIGLEC5 is expressed at high levels in peripheral blood leukocytes, spleen, and at lower levels in lymph node, appendix, pancreas, lung, and thymus.

Sialic acid-binding Ig-like lectin 6 isoform 1 (SIGLEC6) is a member of immunoglobulin superfamily and SIGLEC (sialic acid binding Ig-like lectin) family. SIGLEC6 mediates sialic-acid dependent binding to cells and binds to alpha-2, 6-linked sialic acid. The SIGLEC6 protein localizes in numerous compartments such as membrane fraction, extracellular region and so on. The SIGLEC6 receptor binds sialyl-TN glycans and leptin. Placental expression SIGLEC6 is upregulated in preeclampsia.

Sialic acid-binding Ig-like lectin 7 isoform 1, also known as SIGLEC7, is a newly discovered family of sialic acid-binding lectins of the immunoglobulin (Ig) superfamily. The extracellular portion has two Ig-like domains, with the amino-terminal V-set Ig domain containing amino acid residues which known to be implicated in sialic acid recognition by other Siglecs. The combination of an extracellular sialic acid binding site and an intracellular ITIM motif proposes that SIGLEC7 is involved in trans-membrane regulatory signaling reactions. Furthermore, on the cell surface SIGLEC7 exists as a monomer and is expressed on natural killer cells.

C-type Lectin Domain Family 1 Member B, also known as CLEC1B. NK-Natural killer cells express multiple calcium-dependent (C-type) lectin-like receptors, for instance CD94 (KLRD1; MIM 602894) and NKG2D (KLRC4; MIM 602893), which interact with major histocompatibility complex class I molecules and either inhibit or else activate cytotoxicity and cytokine secretion. CLEC1B is a C-type lectin-like receptor which is expressed in myeloid cells as well as in NK cells.

Hepatitis A virus cellular receptor 1 (HAVCR1) is a membrane receptor for both human hepatitis A virus (HHAV) and TIMD4. HAVCR1 is a type I trans-membrane structural glycoprotein located in the renal proximal tubule epithelial cells. HAVCR1 protein may be involved in the control of asthma and allergic diseases. The reference genome represents an allele which retains a MTTVP amino acid segment that presents defense against atopy in HHAV seropositive individuals.

Leukocyte Cell-Derived Chemotaxin 2 (LECT2) functions as a chemotactic factor to neutrophils. LECT2 stimulates the proliferation of chondrocytes and osteoblasts. LECT2 is strongly expressed in the liver and weakly in the testis. LECT2 is a secreted, 16kDa protein which serves as a chemotactic factor to neutrophils and stimulates the growth of chondrocytes and osteoblasts. LECT2 protein has a high sequence similarity to the chondromodulin repeat regions of the chicken myb-induced myeloid 1 protein. A polymorphism in the LECT2 gene is linked with rheumatoid arthritis.

Leukocyte-associated immunoglobulin-like receptor 2 (LAIR2) is a secreted, 131 amino acids protein which contains one IglikeC2 type domain, rendering it a member of the Ig superfamily. Even though one is secreted and one is membrane bound, the 2 LAIR proteins are assumed to have evolved from a common gene ancestor and seem to share similar adhesion profiles, suggesting that LAIR2 may compete with LAIR1 for ligand binding. LAIR2 was discovered by its similarity to LAIR1, which is an inhibitory receptor present on mononuclear leukocytes. The LAIR2 gene maps to a region of 19q13.4, dubbed the leukocyte receptor cluster, which contains 29 genes in the immunoglobulin superfamily, including LAIR1. The function of the LAIR2 protein is unknown, though it is assumed to be secreted and may help modulate mucosal tolerance.