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Podoplanin is a small mucin-like type-1 transmembrane protein, typically expressed in various specialized cell types throughout the body. Podoplanin is a type-I integral membrane glycoprotein with diverse distribution in human tissues. PDPN physiological function is related to its mucin-type character. The homologous protein in other species has been described as a differentiation antigen and influenza-virus receptor.
PDPN is expressed in lymphatic progenitor cells and afterwards during mouse development in lymphatic endothelial cells. Podoplanin is a specific marker for lymph vessel endothelial cells. Over-expression of podoplanin significantly elevates endothelial cell adhesion, migration, and tube formation. Inhibition of Podoplanin expression decreases cell adhesion in human dermal lymphatic endothelial cells. Podoplanin is used as a specific marker for lymphatic endothelium in histopathology.
Podoplanin expression is increased in nearly all human colon, rectum, and small intestine tumors. AGGRUS may serve as a diagnostic marker that distinguishes seminomas, the majority of which over express the protein, from embryonal carcinoma in testicular germ cell tumors.

The 26S proteasome is a multicatalytic proteinase complex with a well ordered structure composed of two complexes- a 20S core and a 19S regulator. PSMD11 is a non-ATPase subunit of the 19S regulator. The 20S core is composed of four rings of 28 non-identical subunits; two rings are composed of 7 alpha subunits and two rings are composed of 7 beta subunits. The 19S regulator is composed of a base that contains six ATPase subunits and two non-ATPase subunits, and a lid that contains up to ten non-ATPase subunits. Proteasomes are spread throughout eukaryotic cells at a high concentration and cleave peptides in an ATP/ubiquitin-dependent process in a non-lysosomal pathway. An indispensable function of a modified proteasome, the immunoproteasome, is the processing of class I MHC peptides.

Cystatins are a superfamily of cysteine proteinase inhibitors found in both plants and animals. They comprise a group of proteinase inhibitors, widely distributed in tissues and body fluids, and form tight complexes with cysteine proteases such as cathepsin B, H, L and S. Cystatin C, a secreted molecule of this family, is of interest from biochemical, medicine and evolutionary points of view. Cystatin C is increased in patients with malignant diseases, and is related to the insufficiency of renal function and appears to be a better marker than creatinine. On the other hand, low levels of cystatin C involve cause the breakdown of the elastic laminae and subsequently, the atherosclerosis and abdominal aortic aneurysm.

FAD-linked sulfhydryl oxidase ALR (GFER) is a member of the Erv1/ALR family of proteins, which is found in higher and lower eukaryotes. GFER is a hepatotrophic growth factor and flavin-linked sulfhydryl oxidase expressed in a variety of tissues. Moreover, GFER induces the expression of S-adenosylmethionine decarboxyl-ase and ornithine decarboxylases (ODC), which each have a central role in the synthesis of polyamines. The hepatotrophic factor designated augmenter of liver regeneration (ALR) is assumed to be one of the factors responsible for the exceptional regenerative capacity of mammalian liver. The GFER gene is located on chromosome 16 in the interval containing the locus for polycystic kidney disease (PKD1).

Napsin A Aspartic Peptidase, also known as NAPSA is a member of the peptidase A1 family. NAPSA is involved in the processing of pneumocyte surfactant precursors. Furthermore the activation peptides of aspartic proteinases take part as inhibitors of the active site. These peptide segments/pro-parts are considered essential for correct folding, targeting, as well as control of the activation of aspartic proteinase zymogens. The pronapsin A gene is expressed mostly in lung and kidney. In addition, NAPSA translation product is expected to be a fully functional, glycosylated aspartic proteinase precursor which contains an RGD motif as well as an additional 18 residues at its C-terminus.

EFNA1 belongs to the ephrin (EPH) family. The EPH subfamily is the biggest group of receptor protein kinases and they take part in vital nervous system function and development.

Chromosome 19 Open Reading Frame 80 (C19ORF80) is a significant new regulator of lipid metabolism which regulates serum triglyceride levels, possibly by promoting ANGPTL3 cleavage. C19ORF80 belongs to the ANGPTL protein family. C19ORF80 is a hormone which specifically promotes pancreatic beta cell proliferation and beta cell mass expansion, thus improving glucose tolerance. C19ORF80 is mainly expressed in the liver; it is also expressed in adipose tissues. C19ORF80 is expressed in response to food intake and stimulated by insulin.

GMCSF is a cytokine that controls the production, differentiation, and function of granulocytes and macrophages. The active form of the protein is found extracellularly as a homodimer. This gene has been localized to a cluster of related genes at chromosome region 5q31, which is known to be associated with interstitial deletions in the 5q- syndrome and acute myelogenous leukemia. Other genes in the cluster include those encoding interleukins 4, 5, and 13.
GM-CSF stimulates the growth and differentiation of hematopoietic precursor cells from various lineages, including granulocytes, macrophages, eosinophils and erythrocytes. Granulocyte Macrophage Colony Stimulating Factor is a potent species-specific growth factor produced by a variety of cell types including T cells, B cells, macrophages, mast cells and endothelial cells. GM-CSF is produced in response to cytokine or immune stimulation and has been shown to stimulate the proliferation, maturation and function of hematopoietic cells.

Uromodulin is the most abundant protein in normal urine. Its secretion in urine follows proteolytic cleavage of the ectodomain of its glycosyl phosphatidylinosital-anchored counterpart that is situated on the luminal cell surface of the loop of Henle. Uromodulin plays a role as a constitutive inhibitor of calcium crystallization in renal fluids. Secretion of uromodulin in urine provides protection against urinary tract infections caused by uropathogenic bacteria. Defects in Uromodulin expression are associated with the autosomal dominant renal disorders medullary cystic kidney disease-2 (MCKD2) and familial juvenile hyperuricemic nephropathy (FJHN). These disorders are characterized by juvenile onset of hyperuricemia, gout, and progressive renal failure. While several transcript variants may exist for this gene, the full-length natures of only two have been described to date. UMOD is involved in regulating the circulating activity of cytokines as it binds to il-1, il-2 and tnf with high affinity.

Insemination involves of a series of specific cell-cell interactions concluding in the fusion of the sperm and egg plasma membranes. Recognition, binding, and fusion take place through the interface of complementary molecules which are localized to specific domains of the sperm and egg plasma membranes. In the sperm, the postacrosomal region or equatorial segment is involved in sperm-egg plasma membrane fusion. The protein encoded by this gene belongs to the cysteine-rich secretory protein (CRISP) family. CRISP1 is expressed in the epididymis, is secreted into the epididymal lumen, and binds to the postacrosomal region of the sperm head, where it takes part in sperm-egg fusion.

Streptavidin is a tetrameric protein secreted by Streptomyces avidinii which binds firmly to biotin. Streptavidin is widely 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.

SERPINA1 is secreted and is a serine protease inhibitor which its targets include elastase, plasmin, collagenase, leucocytic proteases, trypsin, chymotrypsin, and plasminogen activator. Defects in SERPINA1 gene can cause emphysema or liver disease. SERPINA1 is an endogenous inhibitor of serine proteases and inhibits the catalytic domain of human recombinant matriptase in vitro. Rise in SERPINA1 occurs as an acute phase response to tissue necrosis and inflammation. mutations in SERPINA1 and SLC11A1 genes change the balance between elastase produced by leukocytes during phagocytosis.

a-Synuclein (amino acids 1-140), an acidic neuronal protein of 140 amino acids, is extremely heat-resistant and is natively unfolded with an extended structure primarily composed of random coils. a-synuclein has been suggested to be implicated in the pathogenesis of Parkinson’s disease and related neurodegenerative disorders, and more recently, to be an important regulatory component of vesicular transport in neuronal cells. Moreover, recent studies have shown that a-synuclein has chaperone activity and that this activity is lost upon removing its C-terminal acidic tail (amino acids 96-140).

Methionine aminopeptidase 1 (METAP1) is a member of the peptidase M24A family. METAP1 removes the amino-terminal methionine from nascent proteins. METAP1 releases N-terminal amino acids, preferentially methionine, from peptides and arylamides. METAP1 is essential for normal progression through the cell cycle. The active site of METAP1 contains 2 adjacent divalent metal ions linked by a water molecule or hydroxide ion.

The Melanoma Inhibitory protein (MIA) was identified as an inhibitor of in vitro growth of malignant melanoma cells. The protein contains a SH3 domain. MIA acts as a potent tumor cell growth inhibitor for malignant melanoma cells and some other neuroectodermal tumors, including gliomas, in an autocrine fashion. In a study of human melanoma cell lines with different metastatic capacity MIA mRNA expression appeared to be inversely correlated with pigmentation. MIA has been shown to represent a very sensitive and specific serum marker for systemic malignant melanoma that might be useful for staging of primary melanomas, detection of progression from localized to metastatic disease during follow-up, and monitoring therapy of advanced melanomas.

Matrix metalloproteinase-7 (MMP-7) also known as matrilysin and PUMP (EC 3.4.24.23) cleaves a number of substrates including collagen types IV and X, elastin, fibronectin, gelatin, laminin and proteoglycans. MMP-7 is closely related to the stromelysin family members but is encoded by a different gene. MMP-7 is the smallest of all the MMPs consisting of a pro-peptide domain and a catalytic domain. It lacks the hemopexin-like domain common to other members of the MMPs. MMP-7 is secreted as a 28 kDa proenzyme and can be activated in vitro by organomercurials and trypsin and in vivo by MMP-3 to a 18 kDa active MMP-7 enzyme. Once activated, MMP-7 can activate pro-MMP-1 and pro-MMP-9 but not pro-MMP-2. MMP-7 is widely expressed having been reported in elevated levels in cycling endometrium as well as in colorectal cancers and adenomas, hepatocellular carcinomas, rectal carcinomas, and approximately 50% of gliomas.

Cyclophilin-D is a member of the peptidyl-prolyl cis-trans isomerase (PPIase) family. PPIases catalyze the cis-trans isomerization of proline imidic peptide bonds in oligopeptides and speeds up the protein folding. Cyclophilin-D possess PPIase activity and binds to the immunosuppressant cyclosporin-A. Cyclophilin-D is very well known that its overexpression suppresses the apoptosis in cancer cell. Cyclophilin-D suppresses apoptotic cell death by the use of mitochondrial hexokinase-2 dependent mechanism in cancer cells.

SERPINH1 is part of the serpin superfamily of serine proteinase inhibitors. SEPINH1 expression is induced by heat shock. HSP47 localizes to the endoplasmic reticulum lumen and binds collagen therefore it is a molecular chaperone which takes part in the maturation of collagen molecules, facilitating the folding and assembly of procollagen molecules, retaining unfolded molecules within the ER, and assisting the transport of correctly folded-molecules from the ER to Golgi apparatus. Autoantibodies to HSP47 protein have been found in rheumatoid arthritis. SERPINH1 binds specifically to collagen and acts as a chaperone in the biosynthetic pathway of collagen.

Programmed cell death 1 ligand 2 (PDCD1LG2) which takes part in the costimulatory signal, is necessary for T-cell proliferation. PDCD1LG2 is also involved in IFNG production in a PDCD1-independent way. The interaction with PDCD1 inhibits T-cell proliferation by preventing cytokine production and cell cycle progression.

Calmodulin-2 acts as an intracellular calcium sensor protein. When the intracellular Ca2+ concentration increases, calmodulin can bind up to four Ca2+, changing its conformation and regulating cellular functions such as activation or inhibition of a large number of enzymes, ion channels, and receptors. P53 protein stimulates CALM2 gene expression in 041 cells. CALM-2 is involved in the processes of Ca(2+)-induced neuronal cell death and the blockage of calmodulin attenuates brain injury after cerebral ischemia. Calmodulin-2 mediates the control of a large number of enzymes and other proteins by ca(2+). among the enzymes to be stimulated by the calmodulin-ca(2+) complex are a number of protein kinases and phosphatases.