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Osteoprotegerin, which is a member of the tumor necrosis factor receptor superfamily and is involved in the regulation of bone metabolism. OPGand its ligand (OPGL) are cytokines regulating osteoclasto-genesis. OPGL binds to receptors on the surface of preosteoclasts and stimulates their differentiation into active osteoclasts. This leads to osteoresorption. OPG inhibits this osteoclasto-genesis (OPG is secreted by osteoblasts, and binds to OPGL, thus inhibiting maturation of osteoclasts and osteoresorption). The degree and activity of osteoresorption depend mainly on the balance between OPG and its ligand (OPGL); factors increasing OPGL expression mostly reduce OPG expression and vice versa.

ANXA1 is part of the family of Ca(2+)-dependent phospholipid binding proteins which have a Mw between 35kDa-40kDa and are situated on the cytosolic face of the plasma membrane. ANXA1 protein has a Mw of 40kDa, with phospholipase A2 inhibitory activity to bind from two to four calcium ions with high affinity. Since phospholipase A2 is necessary for the biosynthesis of the potent mediators of inflammation, prostaglandins and leukotrienes, ANXA1 might have potential anti-inflammatory activity. ANXA1 promotes membrane fusion and iplays a role in exocytosis. The recognition of ANXA1 protein by immunocytochemical leads a simple, highly sensitive and specific assay for diagnosis of hairy cell leukemia.

HBsAg is the surface antigenof the Hepatitis-B-Virus (HBV). The capsidof a virus has different surface proteins from the rest of the virus. The antigen is a protein that binds specifically on one of these surface proteins. It is commonly referred to as the Australian Antigen.

PEX19 is vital for peroxisome biogenesis in Saccharomyces cerevisiae. PEX19 is limited to the outer surface of peroxisomes in liver cells and is has a part in the early stage of peroxisome membrane assembly, prior to the import of matrix protein.

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.

IFN-alpha 1b is produced by macrophages, IFN-alpha 1b has antiviral activities and stimulates the production of two enzymes: a protein kinase and an oligoadenylate synthetase.

IFNs are cytokines that are widely known to induce potent anti-viral activity. IFN-a exerts a variety of other biological effects, including antitumor and immunomodulatory activities and are increasingly used clinically to treat a range of malignancies, myelodysplasias and autoimmune diseases.

Fibronectin Type III Domain Containing 5 (Irisin) is a newly discovered hormone, secreted into circulation by muscle, which acts on white adipocytes and promotes WAT “browning”. r-Irisin can reduce body weight and cause induction of brown adipocyte in vivo, including a capacity for thermogenic energy expenditure mediated by uncoupling protein 1 (UCP-1). Irisin mature protein is comprised of 110 amino acid residues and two potential glycosylation sites. High levels of Irisin can be found in the heart whereas Very low expression is found in the colon, pancreas and spleen, if any.

FHIT is a member of the histidine triad gene family. FHIT gene encodes a diadenosine 5',5'''-P1,P3-triphosphate hydrolase involved in purine metabolism. FHIT gene includes the common fragile site FRA3B on chromosome 3, where carcinogen-induced damage can lead to translocations and abnormal transcripts of this gene. The FHIT protein is a tumor suppressor with reduced or no expression in numerous types of cancer. FHIT may also act as a tumor suppressor in normal cells. Alterations and deletions of the FHIT (Fragile Histidine Triad) gene are strongly linked to the genesis and establishment of human tumors of the lung, cervix, breast, colon, stomach, and pancreas. The expression of FHIT is more often lost in cancers of individuals with familial mutations causing deficiency in DNA repair genes such as BRCA1, BRCA2 and MSH2. In vitro FHIT functions as a hydrolase that cleaves diadenosine triphosphate (Ap3A) to ADP and AMP. The FHIT -Ap3A enzyme-substrate complex seems to be the tumor suppressor signal. The restoration of FHIT expression in FHIT -deficient cancer cells leads to apoptosis, involving the intrinsic caspase pathway, in cancer-derived cells and in tumor xenografts.

SERTA domain-containing protein (SERTAD1) functions with E2F-responsive promoters to integrate signals provided by PHD- and/or bromodomain-containing transcription factors. SERTAD1 stimulates E2F-1/DP-1 transcriptional activity. SERTAD1 reduces the activity of cyclin D1/CDK4 resistant to the inhibitory effects of p16(INK4a). In addition, SERTAD1 interacts with the PHD-bromodomain of TIF1, TRIM28/TIF1B and p300/CBP. Furthermore, SERTAD1 binds to DP1 and interacts with CDK4.

Renin is a highly specific endopeptidase which generates angiotensin I from angiotensinogen in the plasma. angiotensin I is an important regulator of blood pressure and electrolyte balance. Renin initiates a cascade of reactions that produce an elevation of blood pressure and increased sodium retention by the kidney.

Plasma protease C1 inhibitor (SERPING1) is a part of the serpin superfamily of serine protease inhibitors. SERPING1 takes part in regulating activation of both the complement and contact systems. That isdue to the fact that SERPING1 regulates the activation of complement factor C1 in addition to the activity of activated C1 by coupling with the active catalytic site at the light chains of C1r and C1s. Lack of SERPING1 results in hereditary angioedema, which is characterized by recurrent episodes of localized angioedema of the skin, gastrointestinal mucosa or upper respiratory mucosa.

MMADHC is a mitochondrial protein which takes part in an early step of vitamin B1 2 metabolism. Vitamin B12 (cobalamin) is vital for regular development and existence in humans. Mutations in MMADHC can result in methylmalonic aciduria and homocystinuria type cblD, a cobalamin metabolism syndrome which is characterized by decreased levels of the coenzymes methylcobalamin and adenosylcobalamin.

SERPINI1 (Neuroserpin) is an inhibitory serpin which is expressed primarily in the central nervous system. Even though the physiological target of SERPINI1 is still vague, amassed evidence suggest that SERPINI1 has an imperative role in controlling proteolytic degradation of extracellular matrix (ECM) during synaptogenesis and the subsequent development of neuronal plasticity. The neuroprotective role of SERPINI1 has been demonstrated in transgenic mice lacking SERPINI1 expression. The deficiency of SERPINI1 in these mice is linked with motor neuron disease characterized by axonal degradation. In humans, defects in SERPINI1, caused by point mutations in the neuroserpin gene, trigger a hereditary disorder known as the familial encephalopathy with neuroserpin inclusion bodies (FENIB).

EFNA3 belongs to the ephrin (EPH) family. The ephrins and EPH-related receptors include thelargest subfamily of receptor protein-tyrosine kinases which have been implicated in mediating developmental events, especially in the nervous system and in erythropoiesis. Ephrins are divided into the ephrin-A (EFNA) class and the ephrin-B (EFNB) class, based on their structures and sequence relationships. The Ephrins from the EFNA class are anchored to the membrane by aglycosylphosphatidylinositol linkage, while the others from the EFNB class are transmembrane proteins.

Complement factor H (CFH) is an important regulatory component of the alternative pathway of complement. CFH is prevents complement activation on host cells and tissues, mainly the kidney. CFH controls the formation and decay of the alternative pathway C3/C5 convertase and acts as a cofactor for factor I which proteolytically inactivates C3b when C3b is bound to factor H. The N-terminal 5 domains of CFH bind to C3b and inhibit binding of factor B thus reducing the formation of C3/C5 convertase. CFH also binds to preformed C3/C5 convertases and causes quick release of the catalytic subunit Bb. These activities are necessary for controlling the spontaneous activation of the alternative pathway amplification process in plasma. In addition, CFH controls the formation and decay of these enzymes when C3b is attached to the surface of particles.

Human TNFRSF10A is a type 1 transmembrane protein in the TNF R superfamily. TNFRSF10A is not expressed in rodents. The trimeric ligand Trail binds TNFRSF10A and induces apoptosis, and recombinant, soluble forms of the receptor inhibit Trail-induced apoptosis. TNFRSF10A is expressed generally in damaged, infected, and malignant cells. TNFRSF10A functions in immune surveillance, inducing apoptosis in cancer cells but not normal cells.

Coagulation factor VIII participates in the intrinsic pathway of blood coagulation; factor VIII is a cofactor for factor IXa which, in the presence of Ca+2 and phospholipids, converts factor X to the activated form Xa. This gene produces two alternatively spliced transcripts. Transcript variant 1 encodes a large glycoprotein, isoform a, which circulates in plasma and associates with von Willebrand factor in a noncovalent complex. This protein undergoes multiple cleavage events. Transcript variant 2 encodes a putative small protein, isoform b, which consists primarily of the phospholipid binding domain of factor VIIIc. This binding domain is essential for coagulant activity. Defects in this gene results in hemophilia A, a common recessive X-linked coagulation disorder.

Complement Factor D (Adipsin), which belongs to the trypsin family of peptidases, is involved in the alternative complement pathway of the complement system where it cleaves factor B. In the alternative complement pathway, Adipsin is best known for its role in humoral suppression of infectious agents. In addition, Adipsin is a serine protease which is secreted by adipocytes into the bloodstream. Ultimately, Adipsin has a high level of expression in fat, proposing a role for adipose tissue in immune system biology.

IFN-gamma produced by lymphocytes activated by specific antigens or mitogens.
IFN-gamma, in addition to having antiviral activity, has important immunoregulatory functions, it is a potent activator of macrophages, and has antiproliferative effects on transformed cells and it can potentiate the antiviral and antitumor effects of the type I interferons.

SRGN is identified as a hematopoietic cell granule proteoglycan. Proteoglycans stored in the secretory granules of various hematopoietic cells also hold a protease-resistant peptide core, and is vital for neutralizing hydrolytic enzymes. SRGN is related to the macromolecular complex of granzymes and perforin that acts as a intermediary of granule-mediated apoptosis.

Geminin is a 25 kDa nuclear protein, which inhibits DNA replication and is degraded during the mitotic phase of the cell cycle. Geminin controls replication by binding to the licensing factor Cdt1, and is involved in neural differentiation. In addition, Geminin directly interacts with Six3 and Hox homeodomain proteins during embryogenesis and inhibits their functions. Geminin can also promote DNA replication. Geminin has 2 roles in 2 different stages of the cell cycle: Geminin is a negative regulator of DNA replication during the “S phase” of the cell cycle. Inhibition of Geminin during the “S phase” (by RNAi) results in an additional round of replication of portions of the genome. During the “M phase” of the cell cycle (mitosis) Geminin stabilizes the replication factor Cdt1 promoting DNA replication during the next cell cycle. Moreover, inhibition of Geminin during mitosis (by RNAi) causes destabilization of Cdt1 protein and impairment of DNA replication during the next cell cycle. Geminin thus guarantees that only one round of replication occurs during each cell cycle. It was discovered that Geminin is overexpressed in a number of malignancies and cancer cell lines. This maintains the concept that Geminin has also a positive role in DNA replication and cell cycle progression. Geminin accumulates through S, G2 and M phases of the cell cycle but is absent during the G1 phase. During the metaphase/anaphase transition of mitosis Geminin levels decrease.

Clusterin also named Apolipoprotein J (APO-J) is a 75-80 kD disulfide-linked heterodimeric protein containing about 30% of N-linked carbohydrate rich in sialic acid but truncated forms targeted to the nucleus have also been identified.
The precursor polypeptide chain is cleaved proteolytically to remove the 22-mer secretory signal peptide and subsequently between residues 227/228 to generate the a and b chains. These are assembled in anti-parallel to give a heterodimeric molecule in which the cysteine-rich centers are linked by five disulfide bridges and are flanked by two predicted coiled-coil a-helices and three predicted amphipathic a-helices.
Across a broad range of species clusterin shows a high degree of sequence homology ranging from 70% to 80%. It is nearly ubiquitously expressed in most mammalian tissues and can be found in plasma, milk, urine, cerebrospinal fluid and semen.
It is able to bind and form complexes with numerous partners such as immunoglobulins, lipids, heparin, bacteria, complement components, paraoxonase, beta amyloid, leptin and others. Clusterin has been ascribed a plethora of functions such as phagocyte recruitment, aggregation induction, complement attack prevention, apoptosis inhibition, membrane remodeling, lipid transport, hormone transport and/or scavenging, matrix metalloproteinase inhibition.
A genuine function of clusterin has not been defined. One tempting hypothesis says that clusterin is an extracellular chaperone protecting cells from stress induced insults caused by degraded and misfolded protein precipitates.
Clusterin is up- or down regulated on the mRNA or protein level in many pathological and clinically relevant situations including cancer, organ regeneration, infection, Alzheimer disease, retinitis pigmentosa, myocardial infarction, renal tubular damage, autoimmunity and others.