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TNFRSF13B (TACI) is a transmembrane receptor protein found predominantly on the surface of B cells (a significant part of the immune system). TACI was at first discovered owing to its ability to interact with calcium-modulator and cyclophilin ligand (CAML). Later on, it was found that TACI plays a key role in humoral immunity by interacting with two members of the TNF family. Also, TACI controls T cell-independent B cell antibody responses, isotype switching, and B cell homeostasis.

C9 binds to the C5b-8 complex and formson cell membranes the mature membrane attack complex. Each pathway of complement activation generates proteolytic enzyme complexes which binds the target surface. These enzymes cleave a peptide bond in the larger alpha chain of C5 releasing the anaphylatoxin C5a and activating C5b. This is the only proteolytic step in the assembly of the C5b-9 complex. Although C5b is unstable it remains bound to the activating complex for a few minutes during which it binds a single C6 from the surrounding fluid or it decays and is no longer capable of forming MAC.The C5b,6 complex may also remain connected to the C3/C5 convertase where the binding of a single C7 exposes a membrane-binding region and C5b,6,7 can enter into the bilipid layer of the target cell. Each C5b-7 complex can bind 1 molecule of C8 causing the complex to enter more firmly into the membrane. The C5b-8 complex can cause lysis without C9,though it will take longer andwill require many more complexes per cell than with C9. The main role of C8 is to catalyze the binding of C9 and each can bind another C9 initiating formation of a ring structure containing up to 18 C9molecules.C5b-9 complexes with 1 or more C9 are called the Membrane Attack Complex of complement.

S100A12 belongs to the S100 family of proteins containing 2 EF-hand calcium-binding motifs. S100 family members are localized in the cytoplasm and/or nucleus of a wide range of cells, and are involved in the regulation of a number of cellular processes such as cell cycle progression and differentiation. S100A12 may be involved in specific calcium-dependent signal transduction pathways and its regulatory effect on cytoskeletal components may modulate various neutrophil activities.

Kallistatin (SERPINA4) inhibits human amidolytic and kininogenase activities of tissue kallikrein. This inhibition is attained by formation of an equimolar, heat- and SDS-stable complex between the inhibitor and the enzyme, and production of a small C-terminal fragment of the inhibitor as a result of cleavage at the reactive site by tissue kallikrein.

HP-NAP protects DNA from oxidative damage by sequestering intracellular Fe2+ ion and storing it in the form of Fe3+ oxyhydroxide mineral. One hydrogen peroxide oxidizes two Fe2+ ions, thus preventing hydroxyl radical production by the Fenton reaction. HP-NAP is necessary for the survival in the presence of oxidative stress. Dps is also a virulence factor which activates neutrophils, mast cells and monocytes. HP-NAP binds to neutrophil-glycosphingolipids and to sulfated carbohydrates on mucin. HP-NAP might play a part in the accumulation of neutrophils and monocytes at the site of infection. HP-NAP induces superoxide anion generation, adhesion and chemotaxis of neutrophils, via a pertussis toxin-sensitive pathway involving MAP kinases.

DnaJ (Hsp40) Homolog, Subfamily C, Member 27 (DNAJC27) which contains one J domain is a part of the small GTPase superfamily. DNAJC27 is a GTPase which activates the MEK/ERK pathway and induces cell transformation when overexpressed.

ASCC1 is a subunit of the triggering signal cointegrator 1 (ASC-1) complex which is a transcriptional coactivator. ASC-1 complex takes a vital part in gene transactivation using various transcription factors such as activating protein 1 (AP-1), nuclear factor kappa-B (NF-kB) and serum response factor (SRF). ASCC1 has an N-terminal KH-type RNA-binding motif, essential for AP-1 transactivation by the ASC-1 complex. Alterations in ASCC1 result in Barrett esophagus and esophageal adenocarcinoma.

Progesterone-Associated Endometrial Protein (PAEP) is a member of the kernel lipocalin super family whose members share rather low sequence similarity but have highly conserved exon/intron structure and three-dimensional protein folding. Most lipocalins are clustered on the long arm of chromosome 9. PAEP protein has been previously referred to as pregnancy-associated endometrial alpha-2-globulin, placental protein 14, and glycodelin.

Synaptotagmin V, (SYT5) is a member of synaptotagmin family, which is a family of type III membrane proteins characterized by cytoplasmic repeats related to protein kinase C regulatory (C2) domains that are considered to bind calcium. Synaptotagmins function as negative regulators of vesicle fusion, allowing fusion in the attendance of calcium, and as calcium receptors or sensor molecules. Among the diseases associated with SYT5 are labyrinthitis, and thyroiditis.

Procollagen C-endopeptidase enhancer 1, also known as PCOLCE binds to the C-terminal propeptide of type I procollagen and enhances procollagen C-proteinase activity. In addition, C-terminal processed part of PCPE (CT-PCPE) has a metalloproteinase inhibitory activity. Among the diseases which are associated with PCOLCE: bone fracture & oculopharyngeal muscular dystrophy.

FAS or tumor necrosis factor receptor superfamily member 6 or TNFRSF6, is part of the death receptor family, which is part of the TNF receptor protein family. TNFRSF6 has a crucial part in regulating viral infections. FAS protein can be found in almost all cell types, when its cognate ligand (FasL) can be found in activated T cells, NK cells & dendritic cells. The regulating protein of FasL & TRAIL on HCMV-infected dendritic enhances direct destruction of activated T lymphocytes. furthermore, subvertneutrophil function in HCMV retinitis can occur when FasL is activated in HCMV infected retinal pigment epithelial cells.

Tubulointerstitial Nephritis Antigen Like 1 also known as TINAGL1 is similar in sequence to tubulointerstitial nephritis antigen, a secreted glycoprotein which is identified by antibodies in several types of immune-related tubulointerstitial nephritis. Three transcript variants encoding different isoforms are known for TINAGL1.

Pyruvate kinase is a key enzyme in the glycolytic pathway. The M2 isoenzyme of pyruvate kinase is specifically expressed at high levels in tumor cells, and can be measured in plasma of patients with advanced breast cancer. The marker is useful for measuring disease activity, sensitivity to chemotherapy and recurrence.

PSMB6 belongs to the proteasome B-type family (T1B family) which is a 20S core beta subunit in the proteasome. The PSMB6 is not present in the immunoproteasome and is replaced by PSMB9. The proteasome is a multicatalytic proteinase complex with an extremely ordered ring-shaped 20S core structure. The core structure is comprised of 4 rings of 28 non-identical subunits; 2 rings are composed of 7 alpha subunits and 2 rings are composed of 7 beta subunits.

Ras-related protein Rab-35 (RAB35) is restricted to the plasma membrane and endocytic compartments and controls a fast endocytic recycling pathway. Inhibition of Rab35 function leads to the accumulation of endocytic markers on numerous cytoplasmic vacuoles in cells that failed cytokinesis, which is consistent with a central requirement for Rab35-regulated recycling during cell division.

Reg protein was shown to be stimulated during the regeneration of pancreatic islets. Since then, many Reg-related proteins have been identified in humans and other animals. In human, the four REG family genes, i.e., REG 1 alpha, REG 1 beta, REG-related sequence (RS) and HIP/PAP, have so far been isolated. These Reg-related proteins are classified into four subfamilies according to their amino-acid sequences, but they share a similar structure and physiological function. Reg protein is a growth factor for pancreatic beta cells and also suggests that the administration of Reg protein could be used as another therapeutic approach for diabetes mellitus. Human REG cDNA which encodes a 166-amino acid protein with a 22-amino acid signal peptide. The amino acid sequence of human REG protein has 68% homology to that of rat Reg protein.
Reg I was found to be expressed mainly in pancreatic beta and acinoductular cells as well as gastric fundic enterochromaffin-like (ECL) cells. Reg I production in ECL cells is stimulated by gastrin, as well as by the proinflammatory cytokine, cytokine-induced neutrophil chemoattractant (CINC)-2Beta. In patients with chronic hypergastrinemia, Reg production is stimulated, with the increased proliferation of gastric mucosal cells. Patients with Helicobacter pylori infection also showed increased Reg production in the gastric mucosa, partly via increased plasma gastrin concentration and partly via increased proinflammatory cytokine production. The serum concentration of the reg-protein was significantly higher in patients with various pancreatic diseases than in normal controls, and was also significantly higher in patients with acute pancreatitis or chronic relapsing pancreatitis than in patients with chronic pancreatitis. Furthermore, the serum PSP/reg-protein concentration was also significantly increased in liver cirrhosis, choledocholithiasis, and various cancers of the digestive system.

Complement C4c is a degradation product of C4b which is cleaved by C4b/C3b inactivator to yield C4d and C4c.
Complement C4c interacts with C1 and C2 to form C3 convertase of the classic activation pathway. Systemic lupus erythematosus (SLE) is often associated with congenital C4 deficiency. Reduced levels of components of the classic pathway (C1, C2, C4, C3) are common after such activation, e.g. in SLE, acute serum sickness and conditions associated with circulating immune complexes.

Actin is a muscle protein localized in the I band of the myofibrils; acting along with myosin, it is responsible for contraction and relaxation of muscle. Each actin protomer binds one molecule of ATP and has one high affinity site for either calcium or magnesium ions, as well as several low affinity sites. Actin exists as a monomer in low salt concentrations, but filaments form rapidly as salt concentration rises, with the consequent hydrolysis of ATP. It occurs in globular (G-actin) and fibrous (F-actin) forms. Actin is found in all eukaryotic cells (except for nematode sperm). Actin is one of the most highly-conserved proteins, differing by no more than 20% in species as diverse as algae and humans. Its other functions include cell motility, cell division and cytokinesis, vesicle and organelle movement, cell signaling, and the establishment and maintenance of cell junctions and cell shape.

PPIases catalyze the cis-trans isomerization of proline imidic peptide bonds in oligopeptides and accelerate the folding of proteins. Cyclophilin-A is a cyclosporin binding-protein and may play a role in cyclosporin A-mediated immunosuppression. Cyclophilin-A can also interact with several HIV proteins, including p55 gag, Vpr, and capsid protein, and has been shown to be necessary for the formation of infectious HIV virions. Multiple pseudogenes that map to different chromosomes have been reported.

Dickkopf-related protein 3 (DKK3) belongs to the DKK protein family including Dkk-1, 2, 3 and -4. DKK3 is a 350 amino acid secreted glycoprotein which is comprised of an N-terminal signal peptide and 2 conserved cysteine-rich domains that are separated by a 12 amino acid linker region. DKK3 is involved in embryonic development through its inhibition of the WNT signaling pathway. DKK3 gene expression is decreased in a variety of cancer cell lines and it may act as a tumor suppressor gene.

Sirtuin-1 (SIRT1) belongs to the sirtuin family of proteins, homologs to the yeast Sir2 protein. Sirtuin family members are characterized by a sirtuin core domain and grouped into 4 classes. The functions of human sirtuins have not yet been established; though, yeast sirtuin proteins are known to regulate epigenetic gene silencing and suppress recombination of rDNA. It has been proposed that the human sirtuins may serve as intracellular regulatory proteins with mono-ADP-ribosyltransferase activity.

Zinc-alpha-2-glycoprotein (AZGP1) protein stimulates lipid degradation in adipocytes and causes the massive fat losses linked with various advanced cancers. AZGP1 may bind polyunsaturated fatty acids.

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.

CXCL14 is involved in immunoregulatory and inflammatory processes. BRAK protein is structurally related to the CXC (Cys-X-Cys) subfamily of cytokines. CXCL14 displays chemotactic activity for monocytes but not for lymphocytes, dendritic cells, neutrophils or macrophages. CXCL14 is involved in the homeostasis of monocyte-derived macrophages.