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The peroxisome proliferator activated receptors (PPARs) are ligandactivated transcription factors within the nuclear receptor superfamily, which play important roles in adipogenesis, glucose homeostasis andinflammation. Three different isotypes can be distinguished; alpha, beta and gamma. PPARg, is mainly expressed in adipose tissue and to lesser extent in colon, the immune system and the retina. Whereas PPARg operates in the catabolism of fatty acids in the liver, PPARg influences the storage of fatty acids in the adipose tissue and plays a role in adipocyte differentiation. PPARg binds to DNA as a heterodimer with retinoid X receptor (RXR), activating expression of target genes after binding ligand.

The protein encoded by this gene is a member of the TNF-receptor superfamily. This receptor contributes to the clonal expansion, survival, and development of T cells. It can also induce proliferation in peripheral monocytes, enhance T cell apoptosis induced by TCR/CD3 triggered activation, and regulate CD28 co-stimulation to promote Th1 cell responses. The expression of this receptor is induced by lymphocyte activation. TRAF adaptor proteins have been shown to bind to this receptor and transduce the signals leading to activation of NF-kappaB.

The glucagon-like peptide-1 receptor, also known as GLP1R, is a receptor protein found on brain neurons and beta cells of the pancreas. GLP1R activates a signalling cascade that leads to the initiation of adenylyl cyclase and increased intracellular cAMP levels. In humans, GLP1R is synthesized by GLP1R gene, which is present on chromosome 6.
GLP1R takes part in the control of blood sugar level by enhancing insulin secretion. GLP1R is a part of the glucagon receptor family of G protein-coupled receptors. GLP1R consists of two domains, one transmembrane (TMD) domain, that binds the N-terminal region of GLP-1. And one extracellular (ECD) which binds the C-terminal helix of GLP-1. The TMD domain contains a fulcrum of polar residues that controls the biased signaling of the receptor, while the transmembrane helical boundaries and extracellular surface are a trigger for biased agonism.

KLRB1 has an inhibitory role on natural killer (NK) cells cytotoxicity which are lymphocytes who facilitate cytotoxicity and secrete cytokines subsequent to immune stimulation. Some genes of the C-type lectin superfamily, like the rodent NKRP1 family of glycoproteins, are expressed by NK cells and take part in NK cell function regulation. KLRB1 holds an extracellular domain with a few characteristic motifs of C-type lectins, a transmembrane domain, and a cytoplasmic domain. Due to its external C terminus KLRB1 is considered to be a type II membrane protein.

Interleukin-2 Receptor Gamma (IL2RG) is a cytokine receptor sub-unit which is common to the receptor complexes for at least six different interleukin receptors. IL2RG is located on the surface of immature blood-forming cells in bone marrow. One end of the IL2RG protein resides outside of the cell where it binds to cytokines and the other end of the IL2RG protein resides in the interior of the cell where it transmits signals to the cell's nucleus. IL2RG teams up with other proteins to direct blood-forming cells to form lymphocytes. In addition, IL2RG directs the growth and maturation of lymphocyte subtypes, which kill viruses, make antibodies, and help regulate the entire immune system.

Frizzled-4, also known as FZD4 is a 7 ­transmembrane glycoprotein which belongs to the Frizzled family within the G-protein coupled receptor superfamily. FZD4 acts as a positive regulator of the Wingless type MMTV integration site signaling pathway. These pathways appear to include interactions with G-proteins. FZD4 is implicated in transduction as well as intercellular transmission of polarity information in the course of tissue morphogenesis and differentiated tissues.

The epidermal growth factor receptor (EGF R) subfamily of receptor tyrosine kinases comprises four members: EGF R (also known as HER1, ErbB1 or ErbB), ErbB2 (Neu, HER-2), ErbB3 (HER-3), and ErbB4 (HER-4). All family members are type I transmembrane glycoprotein that has an extracellular domain which contains two cysteine-rich domains separated by a spacer region that is involved in ligand-binding, and a cytoplasmic domain which has a membrane-proximal tyrosine kinase domain and a C-terminal tail with multiple tyrosine autophosphorylation sites. The human EGF R gene encodes a 1210 amino acid (aa) residue precursor with a 24 aa putative signal peptide, a 621 aa extracellular domain, a 23 aa transmembrane domain, and a 542 aa cytoplasmic domain. EGF R has been shown to bind a subset of the EGF family ligands, including EGF, amphiregulin, TGFa , betacellulin, epiregulin, heparin-binding EGF and neuregulin-2 in the absence of a co-receptor. Ligand binding induces EGF R homodimerization as well as heterdimerization with ErbB2, resulting in kinase activation, tyrosine phosphorylation and cell signaling. EGF R can also be recruited to form heterodimers with the ligand-activated ErbB3 or ErbB4. EGF R signaling has been shown to regulate multiple biological functions including cell proliferation, differentiation, motility and apoptosis. In addition, EGF R signaling has also been shown to play a role in carcinogenesis.

CD32a, also known as FCGR2A, belongs to a family of immunoglobulin Fc receptor genes located on the surface of various immune response cells. FCGR2A which is a cell surface receptor found on phagocytic cells like macrophages and neutrophils, takes part in the process of phagocytosis and clearing of immune complexes. FCGR2A initiates cellular responses against pathogens and soluble antigens by binding to IgG. FCGR2A, which is a low affinity receptor, binds to the Fc region of immunoglobulins gamma.

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.

RANKL binds to tnfrsf11b/opg and to tnfrsf11a/rank. Osteoclast differentiation and activation factor. Augments the ability of dendritic cells to stimulate naive t-cell proliferation. May be an important regulator of interactions between t-cells and dendritic cells and may play a role in the regulation of the t-cell-dependent immune response. sRANKL may also play an important role in enhanced bone-resorption in humoral hypercalcemia of malignancy. By injecting soluble RANKL, novel osteopenia model mice were established in only 50 hours. Degree of bone loss can be controlled by changing doses of sRANKL. RANKL can be used in establishing osteopenia model for in vivo screening of drugs for osteoporosis, determination of effect and mechanism, evaluation of bone anabolic drugs.

Prolactin is a pituitary hormone that plays a role in the stimulation of milk production, salt and water regulation, growth, development and reproduction. The primary step in its action is the binding to a specific membrane receptor (prolactin receptor) which belongs to the superfamily of class 1 cytokine receptors. Prolactin is a hormone involved in a range of significant functions including ion transport and osmoregulation, stimulation of milk, protein synthesis as well as the regulation of numerous reproductive functions. Prolactin exerts its influence on different cell types through a signal transduction pathway which begins with the binding of the hormone to a transmembrane Prolactin receptor. PRLR varies in size (short and long forms) with tissue source and species, from ~40 kDa to 100 kDa. The PRL-R consists of at least 3 separate domains: an extracellular region with 5 cysteines which contains the prolactin binding site, a single transmembrane domain and a cytoplasmic region, the length of which appears to influence ligand binding and regulate cellular function.

Signal-Regulatory Protein Alpha, SIRPA belongs to the signal-regulatory-protein (SIRP) family, as well as the immunoglobulin super family. The members of the SIRP family are receptor-type transmembrane glycoproteins which are involved in the negative regulation of receptor tyrosine kinase-coupled signaling processes.
SIRPA can be phosphorylated by tyrosine kinases. The phospho-tyrosine residues of this PTP have been shown to recruit SH2 domain containing tyrosine phosphatases (PTP), and perform as substrates of PTPs. SIRPA take part in signal transduction mediated by a variety of growth factor receptors. CD47 has been shown to be a ligand for SIRPA.

Fc fragment of IgE, high affinity I, receptor for; alpha polypeptide (FCER1A) binds to the Fc region of immunoglobulins epsilon. FCER1A is a high affinity receptor. In addition FCER1A is responsible for starting the allergic response. Binding of allergen to receptor-bound IgE leads to cell activation and the release of mediators such as histamine which is responsible for the manifestations of allergy. This receptor is contains of an alpha subunit, a beta subunit, and two gamma subunits. FCER1A stands for the alpha subunit. Among the diseases associated with FCER1A are mast-cell leukemia, and allergic asthma.

Low affinity immunoglobulin gamma Fc region receptor III-A (FCGR3A) is a receptor for the Fc portion of immunoglobulin G, and is involved in the elimination of antigen-antibody complexes from the circulation, as well as other antibody-dependent responses. FCGR3A needs to associate with the gamma subunit of Fc epsilon. The FCGR3A receptor is expressed on natural killer (NK) cells as an integral membrane glycoprotein anchored through a transmembrane peptide, while FCGR3B is expressed on polymorphonuclear neutrophils (PMN) where the receptor is anchored through a phosphatidylinositol (PI) linkage. In addition, FCGR3A is expressed on macrophages, subpopulation of T-cells, immature thymocytes and placental trophoblasts. FCGR3A mediates antibody-dependent cellular cytotoxicity (ADCC) and other antibody-dependent responses, such as phagocytosis. FCGR3A gene mutations are linked with susceptibility to recurrent viral infections, susceptibility to systemic lupus erythematosus, and alloimmune neonatal neutropenia.

Peroxisome proliferators are non-genotoxic carcinogens which are purported to exert their effect on cells through their interaction with members of the nuclear hormone receptor family termed peroxisome proliferators activated receptors (PPARs). Nuclear hormone receptors are ligand-dependent intracellular proteins that stimulate transcription of specific genes by binding to specific DNA sequences following activation by the appropriate ligand. Studies indicate that PPARs are activated by peroxisome proliferators such as clofibric acid, nafenopin, and WY-14,643, as well as by some fatty acids.

Low affinity immunoglobulin gamma Fc region receptor III-A (FCGR3A) is a receptor for the Fc portion of immunoglobulin G, and is involved in the elimination of antigen-antibody complexes from the circulation, as well as other antibody-dependent responses. FCGR3A needs to associate with the gamma subunit of Fc epsilon. The FCGR3A receptor is expressed on natural killer (NK) cells as an integral membrane glycoprotein anchored through a transmembrane peptide, while FCGR3B is expressed on polymorphonuclear neutrophils (PMN) where the receptor is anchored through a phosphatidylinositol (PI) linkage. In addition, FCGR3A is expressed on macrophages, subpopulation of T-cells, immature thymocytes and placental trophoblasts. FCGR3A mediates antibody-dependent cellular cytotoxicity (ADCC) and other antibody-dependent responses, such as phagocytosis. FCGR3A gene mutations are linked with susceptibility to recurrent viral infections, susceptibility to systemic lupus erythematosus, and alloimmune neonatal neutropenia.

IL3RA, also known as Interleukin 3 Receptor Subunit Alpha, is a single-pass type 1 membrane protein which is a member of the type 1 cytokine receptor family as well as type 5 subfamily. IL3RA is a pleiotropic cytokine which is produced mainly by activated T cells or mast cells. Moreover, the specific alpha subunit of the interleukin 3 receptor is strongly expressed in a variety of leukemic blasts as well as leukemic stem cells and appears to be a great target for the therapy of leukemias.

Cholinergic Receptor Nicotinic Alpha 3, also known as CHRNA3 is part of the nicotinic acetylcholine receptor family. Proteins of this family form pentameric complexes comprised of both alpha & beta subunits. Furthermore, CHRNA3 is ligand-gated ions channel which prticipates in neurotransmission. CHRNA3 has been associated with an increased risk of smoking initiation as well as an increased susceptibility to lung cancer.

Lymphotoxin Beta Receptor, also known as LTBR takes part in signaling during the development of lymphoid and other organs, lipid metabolism, immune response, and programmed cell death. In addition, the activity of this receptor has been associated to carcinogenesis. Alternatively spliced transcript variants encoding multiple isoforms have been observed for LTBR.

Chromosome 10 Open Reading Frame 54, also known as C10ORF54 is part of the immunoglobulin superfamily. Like a transmembrane molecule, C10ORF54 is expressed in the bone on embryonic stem cells (ESCs), and on tumor cell surface as well. Accordingly, C10ORF54 supports the differentiation of ESC and ehhances BMP4 induced signaling in ESC, however C10ORF54 is also down regulated following to BMP4 exposure.

TRAIL Receptor-3, also known as TNFRSF10C belongs to theTNF-receptor super family. TNFRSF10C contains an extracellular TRAIL-binding domain as well as a transmembranedomain, however no cytoplasmic death domain. Furthermore, TNFRSF10C is not capable of inducing apoptosis, and is considered toact as an antagonistic receptor which protects cells from TRAIL-induced apoptosis.

Synaptotagmin-11 (SYT11) protein may be involved in Ca2+-dependent exocytosis of secretory vesicles through Ca2+ and phospholipid binding to the C2 domain or may function as Ca2+ sensors in the process of vesicular trafficking and exocytosis.