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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, with molecular weight of 13260 Da, is composed of 120 amino acids, lacks carbohydrate and has two disulfide bridges located near the carboxyl terminus. 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.

S100A3 is part of S100 family of proteins containing 2 EF-hand calcium-binding motifs. S100 proteins are localized in the cytoplasm/nucleus of a broad range of cells, and takes part in the regulation of several cellular processes such as cell cycle progression and differentiation. S100A3 has the largest number of cysteines of all S100 proteins. S100A3 has high affinity for Zinc, and is widely expressed in human hair cuticle.

Scavenger mRNA-decapping enzyme (DCPS) is a member of the HIT family. DCPS is required for the complete degradation of mRNAs, both in normal mRNA turnover and in nonsense-mediated mRNA decay. It was shown that DCPS hydrolyzes the residual m7GpppN cap structure after the complete 3'–5' degradation of the mRNA by the exosome. Furthermore, DCPS releases m7GMP and is incapable of cleaving cap structures attached to a long RNA chain.

DUSP21 is a member of the protein-tyrosine phosphatase family. DUSPs inactivate their target kinases by dephosphorylating both the phosphoserine/threonine and phosphotyrosine residuesb. DUSP21 is able to dephosphorylate single and diphosphorylated synthetic MAPK peptides, favoring the phosphotyrosine and diphosphorylated forms over phosphothreonine. DUSP21 is only expressed in testis where there are dephosphorylated phosphotyrosine residues in MAPK peptides.

DUSP23 is a member of the protein-tyrosine phosphatase family. DUSP23 is a protein phosphatase which facilitates dephosphorylation of phosphorylated proteins on Tyr and Ser/Thr residues. In vitro, DUSP23 dephosphorylate p44-ERK1 (MAPK3) but not p54 SAPK-beta (MAPK10). In addition, DUSP23 enhances activation of JNK and p38(MAPK14).

Sclerostin (SOST) is a secreted glycoprotein with a C-terminal cysteine knot-like (CTCK) domain and sequence similarity to the DAN (differential screening-selected gene aberrative in neuroblastoma) family of bone morphogenetic protein (BMP) antagonists. Sclerostin functions as a negative regulator of bone growth, by inhibiting bone formation. SOST is widely expressed at low levels, with highest levels in the bone, cartilage, kidney, liver, bone marrow and primary osteoblasts differentiated for 21 days. SOST gene defects cause sclerosteosis and bone dysplasia.

Serine peptidase inhibitor Kazal type 7 (SPINK7) which includes one Kazal-like domain is most likely serine protease inhibitor. Diseases linked with SPINK7 include esophageal cancer, and oral squamous cell carcinoma

FABP7 is a brain fatty acid binding protein. Fatty acid binding proteins (FABPs) are a family of small, highly conserved, cytoplasmic proteins that bind long-chain fatty acids and other hydrophobic ligands. FABPs are are inovlved in fatty acid uptake, transport, and metabolism. FABP7 is expressed in radial glia by the activation of Notch receptors and binds DHA with the highest affinity among all of FABPs. FABP7 plays an important role in transport of hydrophobic ligand with potential morphogenic activity during cns development. FABP7 is required for the establishment of the radial glial fiber system in developing brain, a system that is necessary for the migration of immature neurons to establish cortical layers (by similarity).

PFDN4 belongs to the prefoldin beta subunit family. PFDN4 is a heterohexameric chaperone protein that can capture unfolded actin and is a possible transcription factor. Six prefoldin polypeptides, prefoldin 1-6, are known.

Thrombomodulin, also referred to THBD, is an endothelial cell-expressed, transmembrane glycoprotein that can form a complex with the coagulation factor, thrombin. This complex increasethe activation of protein C in the anticoagulant pathway by forming a 1:1 stoichiometric complex with thrombin. Thrombomodulinbound thrombin has procoagulant effect at the same time by inhibiting fibrinolysis by cleaving thrombinactivatable fibrinolysis inhibitor (TAFI) into its active form. Reduced levels of thrombomodulin or increased serum levels of THBD can correlate with pathogenesis of certain cardiovascular diseases, such as atherosclerosis and thrombosis. Furthermore, it associated with, diabetes mellitus, liver cirrhosis, cerebral & myocardial infarction, and multiple sclerosis.

KPNB1 is a member of the importin beta family. The KPNB1 protein is engaged in nuclear protein import, either by coupling itself with an adapter protein (e.g., importin-alpha subunit which binds to nuclear localization signals (NLS) in cargo substrates), or by functioning autonomously as a nuclear transport receptor (acts as NLS receptor, docking of the importin/substrate complex to the nuclear pore complex).

GHBP is a transmembrane receptor for growth hormone. Binding of growth hormone to the receptor leads to receptor dimerization and the activation of an intra- and intercellular signal transduction pathway leading to growth. A common alternate allele of this gene, called GHRd3, lacks exon three and has been well-characterized. Mutations in this gene have been associated with Laron syndrome, also known as the growth hormone insensitivity syndrome (GHIS), a disorder characterized by short stature. Other splice variants, including one encoding a soluble form of the protein (GHRtr), have been observed but have not been thoroughly characterized.

GH receptor, also known as GHR is part of the cytokine receptor family. GHR binds 2 receptor molecules and in this manner induces signal transduction through receptor dimerization. Furthermore, at high concentrations, GH performs as an antagonist since there is a large difference in affinities at the respective binding sites. The antagonist action can be enhanced further by reducing binding in the low affinity binding site.

TRIM21 is a member of the tripartite motif (TRIM) family. The TRIM motif includes three zinc-binding domains, a RING, a B-box type 1 and a B-box type 2, and a coiled-coil region. The 52 kDa Ro protein is part of the RoSSA ribonucleoprotein, which includes a single polypeptide and one of four small RNA molecules. The RoSSA particle localizes to both the cytoplasm and the nucleus. Ro/SSA interacts with autoantigens in patients with Sjogren syndrome and systemic lupus erythematosus. Ribonucleoprotein particle is composed of a single polypeptide and one of four small RNA molecules. The RoSSA is present in all mammalian cells studied but has no known function. At least 2 isoforms are present in nucleated and red blood cells, and tissue specific differences in Ro/SSA proteins were identified.

proBDNF (the precursor form of Brain-derived neurotrophic factor) interacts preferentially with p75NTR (the pan-neurotrophin receptor p75) and vps10p domain-containing receptor sortilin and induces neuronal apoptosis, while the mature BDNF selectively binds with great affinity to the TrkB kinase receptor and promotes the survival, growth and differentiation of neurons. Since proneurotrophins and mature neurotrophins bring forth opposite biological effects, proBDNF cleavage in the neuronal system is regulated in a specific and cell-context dependent manner. proBDNF has an important role in negative regulation of neurotrophic actions in the brain.

Legumain, also known as LGMN is a lysosomal cysteine protease which is found in all mouse tissues, however it was mainly abundant in the kidney as well as placenta. LGMN plays an essential role in the endosomal/lysosomal degradation system as the Legumain deficiency causes the accumulation of pro cathepsins B, H & L, another group of lysosomal cysteine proteases. Furthermore, over expression of LGMN in tumors is important for invasion/metastasis.

PSMB1 is part of the proteasome B-type family, also identified as the T1B family, that is a 20S core beta subunit. PSMB1 is tightly linked to the TBP (TATA-binding protein) gene in human and in mouse, and is transcribed in the opposite orientation in both species.The main function of PSMB1 is its degradation activity of unnecessary or damaged proteins by proteolysis. PSMB1 is a multicatalytic proteinase complex which is characterized by its ability to cleave peptides with arg, phe, tyr, leu, and glu adjacent to the leaving group at neutral or slightly basic ph. the proteasome has an atp-dependent proteolytic activity.

Resistin, a product of the RSTN gene, is a peptide hormone belonging to the class of cysteine-rich secreted proteins which is termed the RELM family, and is also described as ADSF (Adipose Tissue- Specific Secretory Factor) and FIZZ3 (Found in Inflammatory Zone). Human resistin contains 108 amino acids as a prepeptide, and its hydrofobic signal peptide is cleaved before its secretion. Resistin circulates in human blood as a dimeric protein consisting of two 92 amino acid polypeptides, which are disulfide-linked via Cys26.
Resistin may be an important link between obesity resistance. Mouse resistin, specifically produced and secreted by adipocyte, acts on skeletal muscle myocytes, hepatocytes and adipocytes themselves so that it reduces their sensitivity. They have also suggested that resistin is present at elevated levels in blood of obese mice, and is down regulated by fasting and antidiabetic drugs. Way et al., on the other hand, have found that resistin expression is severly suppressed in obesity and is stimulated by several antidiabetic drugs.
Other studies have shown that mouse resistin increases during the differentiation of adipocytes, but it also seems to inhibit adipogenesis. In contrast, the human adipogenic differentiation is likely to be associated with a down regulation of resistin gene expression.

Resistin, a product of the RSTN gene, is a peptide hormone belonging to the class of cysteine-rich secreted proteins which is termed the RELM family, and is also described as ADSF (Adipose Tissue- Specific Secretory Factor) and FIZZ3 (Found in Inflammatory Zone). Human resistin contains 108 amino acids as a prepeptide, and its hydrophobic signal peptide is cleaved before its secretion. Resistin circulates in human blood as a dimeric protein consisting of two 92 amino acid polypeptides, which are disulfide-linked via Cys26.
Resistin may be an important link between obesity and insulin resistance. Mouse resistin, specifically produced and secreted by adipocyte, acts on skeletal muscle myocytes, hepatocytes and adipocytes themselves so that it reduces their sensitivity to insulin. Steppan et al. have suggested that resistin suppresses the ability of insulin to stimulate glucose uptake. They have also suggested that resistin is present at elevated levels in blood of obese mice, and is down regulated by fasting and antidiabetic drugs. Way et al., on the other hand, have found that resistin expression is severely suppressed in obesity and is stimulated by several antidiabetic drugs.
Other studies have shown that mouse resistin increases during the differentiation of adipocytes, but it also seems to inhibit adipogenesis. In contrast, the human adipogenic differentiation is likely to be associated with a down regulation of resistin gene expression.

Non-Metastatic Cells 2 or NME2, is a protein, that acts as a nucleoside diphosphate kinase. This protein is of a heterodimeric structure and has 152 aa A & B polypeptide chains that builds the whole protein. Erythrocyte NDP kinase beta subunit has an identical structure to NME2. NDP kinases linked to nucleoside triphosphates synthesis and it appears as though NME2 takes part in regulating signal transduction.

Granulocyte/Macrophage Colony-Stimulating Factors are cytokines that act in hematopoiesis by controlling the production, differentiation, and function of 2 related white cell populations of the blood, the granulocytes and the monocytes-macrophages. CSF-1 induces cells of the monocyte/macrophage lineage. It plays a role in immunological defenses, bone metabolism, lipoproteins clearance, fertility and pregnancy.

Crystallin, Mu (CRYM) is a taxon-specific crystallin protein which binds NADPH and has sequence similarity to bacterial ornithine cyclodeaminases. CRYM doesn’t perform a structural role in lens tissue; instead CRYM binds thyroid hormone for possible regulatory or developmental roles. CRYM gene mutations are linked with autosomal dominant non-syndromic deafness. CRYM specifically catalyzes the reduction of imine bonds in brain substrates which may include cystathionine ketamine and lanthionine ketamine.

Cystatin 11 (CST11) is a member of the Cystatin family. The Cystatin superfamily is comprised of proteins with multiple cystatin-like sequences. Several family members are active cysteine protease inhibitors, other family members have lost or perhaps never developed this inhibitory activity. The Cystatin superfamily consists of three inhibitory families, including the type 1 cystatins (stefins), type 2 cystatins and the kininogens. The type 2 cystatin proteins are a class of cysteine proteinase inhibitors found in a variety of human fluids and secretions. The majority of the type 2 cystatin genes and pseudogenes are contained in the cystatin locus on chromosome 20. CST11 is located in the cystatin locus and encodes an epididymal-specific protein whose specific function has not been verified yet.

S100b is a member of the S100 family of proteins which are a family of EF-hand calcium binding proteins that exist mostly as dimers of the 20 currently identified individual S100 monomers. The S100B homodimer is expressed in cells of the central nervous system, glial cells and in certain peripheral cells e.g. Schwann cells, melanocytes, adipocytes and chondrocytes. S100 proteins are localized either in the cytoplasm or the nucleus of a wide range of cells. S100 proteins are involved in the regulation of a number of cellular processes such as cell cycle progression and differentiation. There are at least 13 members in the S100 gene family, which are located as a cluster on chromosome 1q21; however, S100b is located at 21q22.3. The determination of S100B in serum levels may be used to monitor the extent of brain injury and malignant melanoma. S100b proteins may have a role in Neurite extension, proliferation of melanoma cells, stimulation of Ca2+ fluxes, inhibition of PKC-mediated phosphorylation, astrocytosis and axonal proliferation, and inhibition of microtubule assembly. Chromosomal rearrangements and altered expression of the S100b gene are implicated in several neurological, neoplastic, and other types of diseases, including Alzheimer's disease, Down's syndrome, epilepsy, amyotrophic lateral sclerosis, melanoma, and type I diabetes.