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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.

ANKRD1 takes part in endothelial cell activation and performs as a nuclear transcription factor which negatively controls the expression of cardiac genes.

NELFE is a vital component of NELF complex which represses RNA polymerase II transcript elongation. NELFE is similar to nuclear RNA-binding proteins but does not bind RNA. NELFE contains a tract of alternating basic and acidic residues, mainly arginine and aspartic acid.

Streptavidin is a tetrameric protein secreted by Streptomyces avidinii which binds firmly to biotin. Streptavidin is wilyde used in molecular biology through its unique high affinity for the vitamin biotin. The dissociation constant (Kd) of the biotin-streptavidin complex is about ~10-15 mol/L. The strong affinity recognition of biotin and biotinylated molecules has made streptavidin one of the most important components in diagnostics and laboratory kits. The streptavidin/biotin system has one of the biggest free energies of association of yet observed for noncovalent binding of a protein and small ligand in aqueous solution (K_assoc = 10**14). The complexes are also extremely stable over a wide range of temperature and pH.

Podocalyxin (PODXL) is a greatly glycosylated transmembrane sialoprotein in the CD34 and endoglycan family. The PODXL protein is involved in the regulation of both adhesion and cell morphology and cancer progression. PODXL functions as an anti-adhesive molecule, which retains an open filtration pathway between neighboring foot processes in the podocyte by charge repulsion. Moreover, PODXL serves as a pro-adhesive molecule, enhancing the adherence of cells to immobilized ligands, increasing the rate of migration and cell-cell contacts in an integrin-dependent manner.

Troponin I (TnI), troponin T (TnT) and troponin C (TnC) form the troponin complex of the thin filaments of striated muscle. TnI acts as the inhibitory subunit by blocking actin-myosin interactions and thereby mediating striated muscle relaxation. The TnI subfamily contains 3 genes: TnI-skeletal-fast-twitch, TnI-skeletal-slow-twitch, and TnI-cardiac. The TNNI3 gene encodes the TnI-cardiac protein and isexpressed solely in cardiac muscle tissues. Mutations in the TNNI3 gene cause familial hypertrophic cardiomyopathy type 7 (CMH7) and familial restrictive cardiomyopathy (RCM).

CGB3, belongs to the glycoprotein hormone beta chain family. CGB3 encodes the beta 3 subunit. CGB3 stimulates the expression of GCM1 target genes, as well as the fusogenic protein syncytin-1, to promote placental cell fusion. Furthermore, CGB3 is synthesized in large quantities by the growing placenta, reaching peak concentrations in maternal blood throughout the late first trimester and early mid-trimester of pregnancy. CGB3 is expressed solely by trophoblasts. CGB3 is a significant biomarker in pregnancy and oncology, where it is routinely detected and quantified by specific immunoassays.

Melanoma-associated antigen D1 (MAGED1) belongs to the melanoma antigen gene (MAGE) family and expressed in virtually all normal adult tissues. MAGED1 is involved in the p75 neurotrophin receptor mediated programmed cell death pathway. MAGED1 is involved in Prader-Willi syndrome including hyperphagia, repetitive and compulsive behaviors, and cognitive impairment. MAGED1 is involved in the apoptotic response following NGF (nerve growth factor) binding in neuronal cells. MAGED1 hinders cell cycle progression, and facilitates NGFR-mediated apoptosis. MAGED1 functions as a regulator of the function of DLX family members. MAGED1 has a role in the circadian rythm regulation.

Regulatory Factor X-Associated Ankyrin-Containing Protein (RFXANK) contains ankyrin repeats involved in protein-protein interactions. RFXANK, along with regulatory factor X-associated protein and regulatory factor-5, figures a complex which binds to the X box motif of certain MHC class II gene promoters and activates their transcription. After bound to the promoter, this complex associates with the non-DNA-binding factor MHC class II transactivator, which controls the cell type specificity and inducibility of MHC class II gene expression. Mutations in RFXANK have been linked to bare lymphocyte syndrome type II, complementation group B.

GDF3 is a member of the TGF-beta superfamily though it does not show similarity pattern of conserved cysteine residues. GDF3 is linked to Vg-1 and human BMP-4. GDF3 transcripts are identified mainly in adult bone marrow, spleen, thymus, and adipose tissue. GDF3 expression is upregulated strongly in high-fat-fed C57Bl/6J FABP4/aP2 null mice, which develop obesity but not the related hyperglycemia or hyperinsulinemia characteristic of type II diabetes. GDF3 expression therefore bonds fatty acid metabolism in adipocytes and the expression of a differentiation regulator belonging to the bone morphogenetic proteins.

LIN28 is a marker of undifferentiated human embryonic stem cells and it increases the productivity of the formation of induced pluripotent stem cells from human fibroblasts. LIN28 acts as a 'translational enhancer and therefore leading specific mRNAs to polysomes and causes an increased protein synthesis. LIN28 binds let-7 pre-miRNA and blocks production of the mature let-7 microRNA in mouse embryonic stem cells.

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.

Interleukin-4 is a pleiotropic cytokine produced primarily by activated T lymphocytes, basophils and mast cells. Multiple immune response-modulating functions are performed by IL-4 on a variety of cell types and it has an important role in the regulator of isotype switching, induction of IgE production in B lymphocytes and differentiation of precursor T helper cells. IL-4 binds to both membrane-bound and secreted soluble IL-4 receptors.

Recombinant Hirudin is a potent thrombin inhibitor originally derived from the medicinal leech. Hirudin acts directly on thrombin rather than through other clotting factors. The mechanism of Hirudin-thrombin appears to be unique. The conversion of fibrinogen into fibrin by the serine protease enzyme thrombin is a major event in the final stages of blood coagulation. In the final stages of coagulation prothrombinase converts prothrombin into thrombin. Fibrin is subsequently cross linked by factor XIII to form a blood clot. The primary inhibitor of thrombin in normal blood circulation is antithrombin III. The anticoagulatant activity of hirudin is derived from its ability to inhibit the pro-coagulant activity of thrombin (similar to antithrombin III activity). Hirudin is the strongest natural inhibitor of thrombin. Hirudin binds to and inhibits only the activity of thrombin forms with a specific activity on fibrinogen contrasting to antithrombin III activity. Therefore, hirudin has a thrombolytic activity since it prevents or dissolves the formation of clots and thrombi. Hirudin also has therapeutic significance in blood coagulation disorders, in the treatment of skin hematomas and of superficial varicose veins. Hirudin does not hinder with the biological activity of other serum proteins and can also act on complexed thrombin, thus having an advantage over more common anticoagulants and thrombolytics. It is complicated to extract large quantities of hirudin from natural sources; therefore a method for producing and purifying hirudin using recombinant biotechnology has been developed.

SARS Coronavirus is an enveloped virus containing three outer structural proteins, namely the membrane (M), envelope (E), and spike (S) proteins. Spike (S)-glycoprotein of the virus interacts with a cellular receptor and mediates membrane fusion to allow viral entry into susceptible target cells. Accordingly, S-protein plays an important role in virus infection cycle and is the primary target of neutralizing antibodies.It has recently been shown that SARS is caused by a human coronavirus. Human coronaviruses are the major cause of upper respiratory tract illness in humans, such as the common cold. Coronaviruses are positive-stranded RNA viruses, featuring the largest viral RNA genomes known to date (27-31 kb). The first step in coronavirus infection is binding of the viral spike protein, a 139-kDa protein, to certain receptors on host cells. The spike protein is the main surface antigen of the coronavirus. The most prominent protein in the culture supernatants infected with SARS virus is a 46 kDa nucleocapsid protein. This suggests that the nucleocapsid protein is a major immunogen that may be useful for early diagnostics.

Crk-like protein (CRKL) is a protein kinase containing SH2 and SH3 (src homology) domains which activates the RAS and JUN kinase signaling pathways and transforms fibroblasts in a RAS-dependent manner. CRKL is a substitute of the BCR-ABL tyrosine kinase, it also has a role in fibroblast transformation by BCR-ABL, and has oncogenic potential.

Mannoside Acetylglucosaminyltransferase 2 (MGAT2) is a golgi enzyme catalyzing an vital step in the conversion of oligomannose to complex N-glycans. MGAT2 enzyme has the characteristic glycosyltransferase domains: a short N-terminal cytoplasmic domain, a hydrophobic non-cleavable signal-anchor domain, and a C-terminal catalytic domain. MGAT2 gene mutations may lead to carbohydrate-deficient glycoprotein syndrome, type II.

MGP is vital for the regulation of calcification in the extracellular matrix, particularly in cartilage and arteries. The K-dependent vitamin MGP has five to six residues of Gla, a Ca2+ binding amino acid crucial for vitamin K-dependent gamma carboxylase for its formation. MGP is formed by COOH-terminal processing by carboxypeptidase B-like enzymatic activity and localized in the human bone.

Type 1 cystatins are also called stefins which function as intracellular thiol protease inhibitors. Cystatin-B protein is able to form a dimer stabilized by noncovalent forces, inhibiting papain and cathepsins l, h and b. CSTB protein protects proteases leakage from lysosomes. Mutations in Stefin-B gene cause primary defects in patients with progressive myoclonic epilepsy (EPM1), a degenerative disease of the central nervous system. CSTB is overexpressed & elevated in the serum of HCC patients. Cystatin-B in vivo has a polymeric structure which is sensitive to the redox environment. Cystatin-B inhibits bone resorption by down-regulating intracellular cathepsin K activity despite increased osteoclast survival. Protein and mRNA levels of stefin B are significantly lower in atypical benign meningiomas. Stefins-A & Stefin-B which belong to the type-1 Cystatins, are up-regulated in lung tumours and thus able to counteract harmful tumour-associated proteolytic activity. Human stefin-A & Stefin-B form amyloid fibrils. Copper binding by stefin-B reduces amyloid fibril formation. A number of alternatively spliced CSTB isoforms were recognized in patients with progressive myoclonus epilepsy. Decreased CSTB activity in EPM1 pathogenesis is controled by cathepsins through increased activity of cathepsin-S & cathepsin-L.

Collagen triple helix repeat-containing protein 1 (CTHRC1) functions as a negative regulator of collagen matrix deposition. CTHRC1 is a secreted 28kDa protein which is glycosylated and highly conserved from lower chordates to mammals. CTHRC1 is highly connected with calcified tissues and cartilaginous matrix, but not with endothelial cells. CTHRC1 is detected qualitatively in plasma of healthy human subjects. CTHRC1 plasma levels are also significantly elevated during pregnancy, in diabetes, in inflammatory and infectious conditions, in subjects with acute myeloid leukemia but not in subjects with solid cancers. The hormonal functions of CTHRC1 include regulation of lipid storage and cellular glycogen levels with potentially far-reaching implications for cell metabolism and physiology. CTHRC1 gene deletion leads to fatty liver (steatosis) formation in mice while others exhibited inactivation of the CTHRC1 gene also results in low bone mass.

HMGB2 belongs to the non-histone chromosomal high-mobility group protein family which are chromatin-associated and highly spread in the nucleus of higher eukaryotic cells. HMGB2 can successfully bend DNA and form DNA circles which indicates that HMGB2 facilitates cooperative interactions between cis-acting proteins by promoting DNA flexibility. Additionally, HMGB2 takes part in the final ligation step in DNA end-joining processes of DNA double-strand breaks repair and V(D)J recombination.