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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.

Secernin 1 (SCRN1) which is a member of the peptidase C69 family, regulates exocytosis in mast cells. SCRN1 increases both the level of secretion and the sensitivity of mast cells to stimulation with calcium.

Centromere protein P (CENPP) is component of the CENPA-CAD (nucleosome distal) complex, which is a complex recruited to centromeres and involved in assembly of kinetochore proteins, mitotic progression and chromosome segregation. CENPP protein is involved in incorporation of newly synthesized CENPA into centromeres by way of its interaction with the CENPA-NAC complex.

Omentin is a recently recognized gene highly localized to the mental tissue (visceral adipose tissue). Omentin is present in the stromal vascular cells in the adipose tissue rather than in the adipocytes. Omentin is predominantly expressed in the visceral adipose tissue than the subcutaneous tissue, with the omentin mRNA being 150 times higher in the visceral adipose tissue. Omentin has also been detected in human blood using western blot analysis, and seems to increase insulin-stimulated glucose uptake in 3T3-L1 adipocytes in mice. Omentin seems to increase Akt phosphorylation irrespective of insulin presence. Its role in glucose metabolism and obesity remains to be described; an insulin-sensitizing action is possible.Differences in Omentin expression has been noted in adipose tissue from normals and patients with inflammatory bowel disease although its significance is unknown.

Chromogranin-A Isoform 1 Preproprotein or CHGA is part of the neuroendocrine secretory proteins of the chromogranin/secretogranin family. CHGA is a precursor of numerus enzymes such as pancreastatin, catestatin, vasostatin-1,vasostatin-2, and parastatin. The protein acts as a negative regulator the neuroendocrine activity of autocrine or nearby cells (paracrine). CHGA causes further production of secretory granules that contains insulin in pancreatic islet beta cells.

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.

Resistin, also known as adipose tissue-specific secretory factor (ADSF) is a cysteine-rich peptide derived from adipose tissue. Resistin takes part in the inflammatory response, glucose metabolism, and angiogenesis.Resistin blocks insulinstimulated uptake of glucose by adipocytes and promote glucose release by hepatocytes. As such,Resistin considered to participate in diet‑induced insulin-sensitivity. Resistin causes high levels of lowdensity lipoprotein (LDL), increasing the risk of heart disease.

A 16-kDa peptide hormone secreted from white adipocytes and implicated in the regulation of food intake and energy balance. Leptin provides the key afferent signal from fat cells in the feedback system that controls body fat stores.

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.

E-cadherin (uvomorulin, cell-CAM120/80) is a calcium dependent cell adhesion molecule expressed predominately in epithelial tissues. It plays an important role in the growth and development of cells via the mechanisms of control of tissue architecture and the maintenance of tissue integrity. Numerous studies have demonstrated that reduction and/or loss of Ecadherin expression in carcinomas correlates positively with the potential of these tumors for invasion and metastasis.

Centromere proteins are a group of proteins which form and/or mediate the function of centromeres, the central structures of chromosomes to which spindle fibers/microtubuli attach and pull the chromosomes apart in cell division. Currently, 9 centromere proteins are known and designated CENPA to CENP-I. Most of the centromere proteins are targets of autoantibodies, the anti-centromere antibodies.
CENPA is another important centromeric autoantigen in addition to CENPB: it has a molecular weight of approx. 20 kDa and is incorporated into centromeric chromatin due to its histone-like properties. CENPA antibodies are an important marker for correct diagnosis of Scleroderma / CREST syndrome in CENPB-autoantibody negative patients.

Vimentin expression in human malignant glioma cells depends on cellular density, algorithms of drug delivery and chemo/radio treatment. Vimentin and detyrosinated microtubules provide structural support for the extensive microtentacles observed in detached tumor cells and a mechanism to promote successful metastatic spread. Primary colorectal carcinomas display aberrant expression of vimentin, and have activated Notch and TGFbeta signaling pathways. Vimentin is a strong arterial substrate for transglutaminases. Transglutaminase-mediated vimentin dimerization results in a novel unifying pathway by which vasodilatory and remodeling responses may be regulated. Ablation of vimentin expression inhibits migration and invasion of colon and breast cancer cell lines. Vimentin is the main intermediate filament protein in mesenchymal cells and is therefore of value in the differential diagnosis of undifferentiated neoplasms.

Excess adiposity is the most important risk in the development of insulin resistance and type 2 diabetes mellitus (T2DM). Adipose tissue produces several proteins (adipocytokines) such as leptin, adiponectin, resistin, tumor necrosis factor-?, and IL-6, that modulate insulin sensitivity and appear to play an important role in the pathogenesis of insulin resistance, diabetes, dyslipidemia, inflammation, and atherosclerosis. However, the mechanisms by which fat tissue induces insulin resistance and the role of adipocytokines in the pathogenesis of T2DM have not been well established. Visfatin, also known as pre-B cell colony-enhancing factor (PBEF), is a cytokine that is highly expressed in visceral fat and was originally isolated as a secreted factor that synergizes with IL-7 and stem cell factors to promote the growth of B cell precursors. Visfatin homologs have been identified in carp, invertebrate mollusks, and bacteria, as well as in vertebrates, including humans and the mouse. It has been postulated to play a role in innate immunity.
Visfatin exerts insulin-mimetic effects that are dose-dependent and quantitatively similar to those of insulin in stimulating muscle and adipocyte glucose transport, and in inhibiting hepatocyte glucose production. Intravenous injection of recombinant visfatin in mice decreased plasma glucose in a dose-dependent fashion. In keeping with its insulin-mimetic effects, visfatin was as effective as insulin in reducing hyperglycemia in insulin-deficient diabetic mice. Visfatin was also found to be bound to and activate insulin receptor, causing receptor phosphorylation and the activation of downstream signaling molecules. However, visfatin and insulin did not compete for binding to the insulin receptor, indicating that the two proteins were recognized by different regions of the receptor. Thus, visfatin might play a role in glucose homeostasis and dysregulation in biosynthesis or signal transduction, and might contribute to the pathogenesis of diabetes.

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.

Connective Tissue Growth Factor belongs to the CCN family of proteins. The CCN family presently consists of six members in human also known as: Cyr61 (Cystein rich 61), CTGF (Connective Tissue Growth Factor), Nov (Nephroblastoma Overexpressed gene), WISP-1, 2 and 3 (Wnt-1 Induced Secreted Proteins). The CCN genes encode secreted proteins associated with the Extracellular Matrix (ECM) and cell membrane.
CCN proteins are matricellular proteins which are involved in the regulation of various cellular functions including: proliferation, differentiation, survival, adhesion and migration. They are expressed in derivatives of the three embryonic sheets and are implicated in the development of kidney, nervous system, muscle, bone marrow, cartilage and bone. During adulthood, they are implicated in wound healing, bone fracture repair, and pathologies such as: fibrosis, vascular ailments and tumorigenesis.
Full length secreted CCN proteins can show an antiproliferative activity, whereas truncated isoforms are likely to stimulate proliferation and behave as oncogenes.
The full length protein consists of four modules: Module I shares partial identity with the N-terminal part of the Insulin-like Growth Factor Binding Proteins (IGFBPs).
Module II includes a stretch of 70amino acid residues – which shares sequence identity with the Von Willebrand Factor Type C repeat (VWC).
Module III contains sequences sharing identity with the Thrombospondin type 1 repeat (TSP1) (WSXCSXXCG), which is thought to be implicated in the binding of sulfated glycoconjugates and to be important for cell adhesion.
Module IV, also designated CT, is encoded by exon5. It is the leasts conserved one of the four domains at the level of nucleotide sequence, but it appears to be critical for several of the biological functions attributed to the CCN proteins. Module IV resembles the CT domain of several extracellular protein including, Von Willebrand's factor and mucins. Sequence similarities to heparin-binding motifs are also found within this domain.
Proteolysis of the secreted full-length CCN proteins that has been reported in the case of CCN2 and CCN3 might result in the production of CCN-derived peptides with high affinity for ligands that full-length CNN proteins bind only poorly. Amino-truncated CCN2 isoforms were biologically active whereas no specific biological activity has been attributed to the truncated CCN3. Although the molecular processes underlying the production of these secreted isoforms is presently unknown, it is important to note that proteolysis occur at the same amino acid residues in both CCN2 and CCN3. An elevated expression of CCN2 has also been detected by Northern blotting in human invasive mammary ductal carcinomas, dermatofibromas, pyogenic granuloma, endothelial cells of angiolipomas and angioleiomyomas, and in pancreatic tumors. A study performed with chondrosarcomas representative of various histological grades established that CCN2 expression was closely correlated with increasing levels of malignancy.
In agreement with CCN2 playing a role in brain tumor angiogenesis, immunocytochemistry studies indicated that both glioblastoma tumor cells and proliferating endothelial cells stained positive for CCN2. In astrocytomas, CCN2 expression was particularly elevated in high grade tumors, with a marked effect of CCN2 on cell proliferation. Downregulation of CCN2 expression in these cells was associated with a growth arrest at the G1/S transition while over-expression of CCN2 induced a two-fold increase of the number of cells in the G1 phase. Gene profiling analysis allowed to identify a set of about 50 genes whose expression might account for the proliferative activity of CCN2 in these cells.
CCN2 was seen in a higher proportion of mononuclear cells of patients with acute lymphoblastic leukemia.

The Casein kinase 2 (EC2.7.11.1) is a serine/threonine-selective protein kinasethat is a tetramer of two alpha subunits and two beta subunits. The alpha subunits have the catalytic kinase domain. Casein kinase 2 has been implicated in cell cyclecontrol, DNA repair, regulation of the circadian rhythmand other cellular processes.
Casein kinase 2 activity has been reported to be activated following Wnt signaling pathwayactivation. A Pertussis toxin-sensitive G proteinand Disheveled appear to be an intermediary between Wnt-mediated activation of the Frizzled receptor and activation of casein kinase 2.
Mice that lack casein kinase 2 alpha prime have a defect in the morphology of developing sperm.

Ciliary Neurotrophic Factor Receptor (CNTFR) is a member of the type I cytokine receptor family and binds to CNTF. The alpha subunit provides the receptor specificity. Sole nucleotide polymorphisms in CNTFR has been associated with variations in muscle strength, in addition to early onset of eating disorders.

Adiponectin, also referred to as Acrp30, AdipoQ and GBP-28, is a recently discovered 244 amino acid protein, the product of the apM1 gene, which is physiologically active and specifically and highly expressed in adipose cells (Adipokine). The protein belongs to the soluble defense collagen super family; it has a collagen-like domain structurally homologous with collagen VIII and X and complement factor C1q-like globular domain. APM-1 forms homotrimers, which are the building blocks for higher order complexes found circulating in serum.

CRK belongs to the signaling adapter protein family which binds to several tyrosine-phosphorylated proteins. CRK is involved in many cellular processes such as apoptosis, proliferation, and differentiation. CRK has a modular domain architecture consisting of an SH2 followed by two SH3 domains (src-homology domains). The N-terminal SH2 domain of the CRK protein functions as a positive regulator of transformation whereas the C-terminal SH3 domain functions as a negative regulator of transformation.

Myozenin 1 (MYOZ1) is a member of the myozenin family. MYOZ1 is mostly expressed in the skeletal muscle. Members of the myozenin family act as calcineurin-interacting proteins which helps tether calcineurin to the sarcomere of cardiac and skeletal muscle. The myozenin family plays a significant role in modulation of calcineurin signaling.

Intein is a section of a protein which can remove itself and return the remaining segment with a peptide bond. In addition, Inteins hold an endonuclease domain which takes part in Intein proliferation. Actually, various genes have unrelated intein-coding segments inserted at altered positions and they were found in all three domains of life (eukaryotes, bacteria, and archaea) and in viruses.

Cyclin-dependent kinase 1 (CDK1) plays a significant part in the control of the eukaryotic cell cycle through modulating the centrosome cycle in addition to mitotic onset; CDK1 promotes G2-M transition and regulates G1 progress and G1-S transition using association with multiple interphase cyclins. CDK1 is essential in higher cells for the entry into S-phase and mitosis.

CENPH is a member of the centromere protein H family. CENPH protein is a component of the CENPA-NAC (nucleosome-associated) complex which has a vital part in assembly of kinetochore proteins. The CENPA-NAC complex utilizes the CENPA-CAD (nucleosome distal) complex and is involved in integration of freshly synthesized CENPA into centromeres.

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.