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TIE-1 (tyrosine kinase with Ig and EGF homology domains 1) and TIE-2/Tek comprise a receptor tyrosine kinase (RTK) subfamily with unique structural characteristics: two immunoglobulin-like domains flanking three epidermal growth factor (EGF)-like domains and followed by three fibronectin type III-like repeats in the extracellular region and a split tyrosine kinase domain in the cytoplasmic region. These receptors are expressed primarily on endothelial and hematopoietic progenitor cells and play critical roles in angiogenesis, vasculogenesis and hematopoiesis. Human TIE-1 cDNA encodes a 1122 amino acid (aa) residue precursor protein with an 18 residue putative signal peptide, a 726 residue extracellular domain and a 353 residue cytoplasmic domain. Two ligands, angiopoietin-1 (Ang1) and angiopoietin-2 (Ang2), which bind TIE-2 with high-affinity have been identified. Ang2 has been reported to act as an antagonist for Ang1. Mice engineered to overexpress Ang2 or to lack Ang1 or Tie-1 display similar angiogenic defects.

Neural Cell Adhesion Molecule 1 (NCAM1) is apart of the immunoglobulin superfamily. NCAM1 bindsspecifically to neurite fasciculation, neuronneuron adhesion, outgrowth of neurites, and more. The polysialyation of NCAM1 reduces its adhesive property and increases its neurite outgrowth promoting features.NCAM1is mainly expressed in NK cells and a subset of T lymphocytes that mediate MHC-unrestricted cellmediated cytotoxicity. High expression of NCAM-1 differentiates NK cells as having an activated phenotype. During hematopoiesis, NCAM1plays a role as the prototypic marker of NK cells and also present on subset of CD4+, CD8+ and T cells. In cell adhesion, NCAM1 contributes to cell-cell adhesion during embryonic development.

Nectin-1, also referred to as ED4, is a poliovirus receptor- related 1 protein is a part of the Nectin family. Nectin-1 endorses cell-cell contacts by forming homophilic or heterophilic trans-dimers. Heterophilic interactions among PVRL1/nectin-1 & PVRL4/nectin-4 and among PVRL1/nectin-1 & PVRL3/nectin-3 have been found. Nectin-1 acts as an entry receptor for herpes simplex virus & pseudorabies virus as well. Likewise, Neurite outgrowth-promoting activity has been shown by Nectin-1.

Enoyl CoA hydratase domain containing 1 (ECHDC1) is a member of the enoyl-CoA hydratase/isomerase family. ECHDC1 is an enzyme which hydrates the double bond between the second and third carbons on acyl-CoA. The ECHDC1 enzyme is crucial to metabolizing fatty acids to supply both acetyl CoA and energy.

Leukocyte Cell Derived Chemotaxin 1 (214-333 a.a.), also known as LECT1, is a glycosylated transmembrane protein which is cleaved to form a mature, secreted protein. The mature protein encourages chondrocyte growth and inhibits angiogenesis. The mature protein takes part in endochondral bone development by permitting cartilaginous anlagen to be vascularized and replaced by bone. LECT1 is expressed in the avascular area of prehypertrophic cartilage and its expression reduces during vascular invasion and chondrocyte hypertrophy.

L1 Cell Adhesion Molecule (L1CAM) which is a cell adhesion receptor of the immunoglobulin superfamily takes part in nerve cell function. L1CAM is a neural cell adhesion molecule involved in the dynamics of cell adhesion and in the generation of transmembrane signals at tyrosine kinase receptors. L1CAM takes part in cell migration, neurite outgrowth and myelination. Furthermore, L1CAM plays an important role in the dynamics of neuronal structure and function in the mature brain.

Endothelial cells express three different vascular endothelial growth factor (VEGF) receptors, belonging to the family of receptor tyrosine kinases (RTKs). They are named VEGFR-1 (Flt-1), VEGFR-2 (KDR/Flk-1), and VEGFR-3 (Flt-4). Their expression is almost exclusively restricted to endothelial cells, but VEGFR-1 can also be found on monocytes. All VEGF-receptors have seven immunoglobulin-like extracellular domains, a single transmembrane region and an intracellular split tyrosine kinase domain. VEGFR-2 has a lower affinity for VEGF than the Flt-1 receptor, but a higher signalling activity. Mitogenic activity in endothelial cells is mainly mediated by VEGFR-2 leading to their proliferation. Differential splicing of the flt-1 gene leads to the formation of a secreted, soluble variant of VEGFR-1 (sVEGFR-1). No naturally occurring, secreted forms of VEGFR-2 have so far been reported. The binding of VEGF165 to VEGFR-2 is dependent on heparin.

EPCAM is a carcinoma-associated antigen and belongs to a family which includes at least 2 type I membrane proteins. The EPCAM protein has a role in embryonic stem cells proliferation and differentiation. EPCAM is used as a target for immunotherapy treatment of human carcinomas. EPCAM is expressed on most normal epithelial cells and gastrointestinal carcinomas and acts as a homotypic calcium-independent cell adhesion molecule. Epithelial cell adhesion molecules (EPCAM) can act as a physical homophilic interaction molecule between intestinal epithelial cells (IECs) and intraepithelial lymphocytes (IELs) at the mucosal epithelium for supplying immunological barrier as a first line of defense against mucosal infection. EPCAM gene mutations result in congenital tufting enteropathy.

Endothelial cells express three different vascular endothelial growth factor (VEGF) receptors, belonging to the family of receptor tyrosine kinases (RTKs). They are named VEGFR-1 (Flt-1), VEGFR-2 (KDR/Flk-1), VEGFR-3 (Flt-4). Their expression is almost exclusively restricted to endothelial cells, but VEGFR-1 can also be found on monocytes, dendritic cells and on trophoblast cells. The flt-1 gene was first described in 1990. The receptor contains seven immunoglobulin-like extracellular domains, a single transmembrane region and an intracellular splited tyrosine kinase domain. Compared to VEGFR-2 the Flt-1 receptor has a higher affinity for VEGF but a weaker signaling activity. VEGFR-1 thus leads not to proliferation of endothelial cells, but mediates signals for differentiation. Interestingly a naturally occuring soluble variant of VEGFR-1 (sVEGFR-1) was found in HUVE supernatants in 1996, which is generated by alternative splicing of the flt-1 mRNA. The biological functions of sVEGFR-1 still are not clear, but it seems to be an endogenous regulator of angiogenesis, binding VEGF with the same affinity as the full-length receptor.

Vascular endothelial growth factor is an important signaling protein involved in both vasculogenesis and angiogenesis. As its name implies, VEGF activity has been mostly studied on cells of the vascular endothelium, although it does have effects on a number of other cell types (e.g. stimulation monocyte/ macrophagemigration, neurons, cancer cells, kidney epithelial cells ).VEGF mediates increased vascular permeability, induces angiogenesis, vasculogenesis and endothelial cell growth, promotes cell migration, and inhibits apoptosis. In vitro, VEGF has been shown to stimulate endothelial cell mitogenesisand cell migration. VEGF is also a vasodilator and increases microvascular permeability and was originally referred to as vascular permeability factor.
Elevated levels of this protein are linked to POEMS syndrome, also known as Crow-Fukase syndrome. Mutations in this gene have been associated with proliferative and nonproliferative diabetic retinopathy.

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.

Vanin 1 (VNN1) belongs to the vanin family of proteins, which share extensive sequence similarity with each other, and also with biotinidase. This family includes secreted and membrane-associated proteins, a few of which have been described to participate in hematopoietic cell trafficking. No biotinidase activity has been established for any of the vanin proteins; nevertheless, they possess pantetheinase activity, which may have a role in oxidative-stress response. VNN1 protein, like its mouse homolog, is probably a GPI-anchored cell surface molecule. The mouse VNN1 protein is expressed by the perivascular thymic stromal cells and regulates migration of T-cell progenitors to the thymus. VNN1 is an amidohydrolase which hydrolyzes specifically one of the carboamide linkages in D-pantetheine thus recycling pantothenic acid (vitamin B5).

Basal Cell Adhesion Molecule (BCAM) which is a product of alternate splicing of the Lutheran blood group molecule is a part of the immunoglobulin superfamily. BCAM contains five extracellular immunoglobulin domains, a single transmembrane domain, and a short C-terminal cytoplasmic tail. BCAM protein is upregulated following malignant transformation of some cell types in vivo and in vitro. Furthermore, BCAM interacts with integrin in sickle red cells, and participates in vasoocclusive episodes.

Endothelial cells express three different vascular endothelial growth factor (VEGF) receptors, belonging to the family of receptor tyrosine kinases (RTKs). They are named VEGFR-1 (Flt-1), VEGFR-2 (KDR/Flk-1), VEGFR-3 (Flt-4). Their expression is almost exclusively restricted to endothelial cells, but VEGFR-1 can also be found on monocytes, dendritic cells and on trophoblast cells. The flt-1 gene was first described in 1990. The receptor contains seven immunoglobulin-like extracellular domains, a single transmembrane region and an intracellular splited tyrosine kinase domain. Compared to VEGFR-2 the Flt-1 receptor has a higher affinity for VEGF but a weaker signaling activity. VEGFR-1 thus leads not to proliferation of endothelial cells, but mediates signals for differentiation. Interestingly a naturally occuring soluble variant of VEGFR-1 (sVEGFR-1) was found in HUVE supernatants in 1996, which is generated by alternative splicing of the flt-1 mRNA. The biological functions of sVEGFR-1 still are not clear, but it seems to be an endogenous regulator of angiogenesis, binding VEGF with the same affinity as the full-length receptor.

The scaffolding protein encoded by the CAV1 gene is the key component of the caveolae plasma membranes found in most cell types. Cholesterol is vital for caveolae formation and maintenance, and caveolae structure is highly sensitive to cholesterol depletion or treatment with cholesterol binding drugs. CAV1 can tightly and specifically bind free cholesterol and artificial cholesterol containing vesicles. Caveolin 1 links integrin subunits to the tyrosine kinase FYN, which is an initiating step in coupling integrins to the Ras-ERK pathway and promoting cell cycle progression. CAV1 is a tumor suppressor gene candidate and a negative regulator of the Ras-p42/44 mitogen-activated kinase. Caveolin 1 and caveolin 2 are positioned next to each other on chromosome 7 and express co-localizing proteins which form a stable hetero-oligomeric complex cascade. Mutations in the CAV1 gene are linked to Berardinelli-Seip congenital lipodystrophy.

Inhibitor of Growth Family Member 1, also known as ING1 is a tumor suppressor protein which is able to induce cell growth arrest and apoptosis. ING1 is a nuclear protein which physically act together with the tumor suppressor protein TP53 and is a component of the p53 signaling pathway. In addition, Reduced expression and rearrangement of ING1 have been identified in various cancers. Multiple alternatively spliced transcript variants encoding distinct isoforms have been described for ING1.

VCAM1 is a member of the Ig superfamily. It is a cell surface sialoglycoprotein expressed by cytokine activated endothelium. VCAM-1 contains 6 or 7 immunoglobulin domains, and is expressed on both large and small vessels only after the endothelial cells are stimulated by cytokines. The protein has a number of functions including the regulation of leukocyte migration, leukocyte endothelial cell adhesion and signal transduction and may play a role in a number of inflammatory diseases (artherosclerosis and rheumatoid arthritis).

V-Set Domain Containing T Cell Activation Inhibitor 1, also known as VCTN1, is part of the B7 costimulatory protein family. Proteins in this family are located on the surface of antigen-presenting cells and interact with ligand bound to receptors on the surface of T cells. High level of the encoded protein has been associated with tumor progression. VCTN1 also takes part in promoting epithelial cell transformation.

Overexpression of the HIF1AN is linked with tumor aggressiveness in pancreatic endocrine tumors. HIF1AN hydroxylates Notch ICD at two residues that are crucial for the function of Notch ICD as a transactivator within cells and during neurogenesis and myogenesis. HIF1AN is commonly expressed in invasive breast carcinoma. The hypoxic response and survival recommends that tumour regulation of HIF1AN is an additional important mechanism for HIF pathway activation. HIF1AN is an asparaginyl hydroxylase enzyme that controls the transcriptional activity of hypoxia-inducible factor. FIH1 is a part of the Fe2+ and 2-oxoglutarate-dependent dioxygenase superfamily, FIH1 is protein that hydoxylates a specific asparagine residue (Asn-803) within the HIF1A C-terminal transactivation domain. In normoxia, the HIF1AN-mediated hydroxylation of the HIF1? transactivation domain which results in blockage of the HIF1A-p300/CBP interaction and represses transcriptional activity of HIF1A targeted genes.

Endothelial cells express three different vascular endothelial growth factor (VEGF) receptors, belonging to the family of receptor tyrosine kinases (RTKs). They are named VEGFR-1 (Flt-1), VEGFR-2 (KDR/Flk-1), VEGFR-3 (Flt-4). Their expression is almost exclusively restricted to endothelial cells, but VEGFR-1 can also be found on monocytes, dendritic cells and on trophoblast cells. The flt-1 gene was first described in 1990. The receptor contains seven immunoglobulin-like extracellular domains, a single transmembrane region and an intracellular splited tyrosine kinase domain. Compared to VEGFR-2 the Flt-1 receptor has a higher affinity for VEGF but a weaker signaling activity. VEGFR-1 thus leads not to proliferation of endothelial cells, but mediates signals for differentiation. Interestingly a naturally occuring soluble variant of VEGFR-1 (sVEGFR-1) was found in HUVE supernatants in 1996, which is generated by alternative splicing of the flt-1 mRNA. The biological functions of sVEGFR-1 still are not clear, but it seems to be an endogenous regulator of angiogenesis, binding VEGF with the same affinity as the full-length receptor.

Plasminogen activator inhibitor-1 is the principal inhibitor of tissue plasminogen activator(tPA) and uPA, the activators of plasminogenand hence fibrinolysis(the physiological breakdown of blood clots). It is a serine protease inhibitor(serpin) protein (SERPINE1). The other PAI, plasminogen activator inhibitor-2(PAI-2) is secreted by the placentaand only present in significant amounts during pregnancy. In addition, protease nexinacts as an inhibitor of tPA. SERPINE1, however, is the main inhibitor of the plasminogen activators.

Cadherin-5 (CDH5) belongs to the atypical/type 2 subgroup of Cadherin homophilic adhesion proteins. Cadherin-5 is a calcium-dependent cell-cell adhesion molecule, which is comprised of 5 extracellular cadherin repeats, a transmembrane region and a highly conserved cytoplasmic tail. Cadherin-5 protein plays a role in the formation, maturation and remodeling of the vascular wall. CDH5 is generally considered to be specific for vascular endothelia in which it is either the sole or the predominant cadherin, often co-existing with N-cadherin. Moreover, the CDH5 protein regulates or is regulated by VEGF R2, type 1 and type 2 TGF-beta receptors, and other endothelial junction proteins such as JAM-C, Claudin-5, and N-Cadherin. CDH5 also connects with alpha-catenin forming a link to the cytoskeleton. CDH5 functions jointly with KRIT1 to create and maintain correct endothelial cell polarity and vascular lumen. Furthermore, Cadherin-5 is essential for activation of PRKCZ and for the localization of phosphorylated PRKCZ, PARD3, TIAM1 and RAP1B to the cell junction. The CDH5 gene is located in a gene cluster in a region on the long arm of chromosome 16 which is involved in loss of heterozygosity events in breast and prostate cancer.