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Ubiquitin thioesterase OTUB2 (OTUB2) is a member of the peptidase C65 family. OTUB2 functions as a hydrolase which can remove conjugated ubiquitin from proteins in vitro and may thus play a key regulatory role at the level of protein turnover by preventing degradation.

ArsA Arsenite Transporter, ATP-Binding, Homolog 1 (ASNA1) is a part of the arsA ATPase family. ASNA1 is the human homolog of the bacterial arsA gene. ArsA ATPase is the catalytic component of a multisubunit oxyanion pump In E.coli, which is in charge for resistance to arsenicals and antimonials. ASNA1 is also a main component of a transmembrane domain (TMD) recognition complex (TRC) which is involved in the post-translational delivery of tail-anchored (TA) proteins from the cytosol to the endoplasmic reticulum (ER).

GIPC2 is a 315 aa protein which is restricted to the cytoplasm and holds one PDZ domain. GIPC2 is expressed in large quantities in colon and kidney and in small quantities in adult liver. GIPC2 has a vital part in human gastric cancer by control of growth factor signaling or cell adhesion.

Mitochondrial Ribosome Recycling Factor (MRRF) is a member of the RRF family. MRRF attaches to the large ribosomal subunit in the cleft which has a peptidyl transferase center. MRRF controls the release of ribosome from messenger RNA at the termination of protein biosynthesis. Also, it may intensify the efficacy of translation by recycling ribosome from one round of translation to another.

CRABP1 is a member of special carrier proteins for members of the vitamin A family. It is believed that CRABP1 has an essential role in retinoic acid-mediated differentiation and proliferation processes. Though, CRABP1 is structurally similar to the cellular retinol-binding proteins, it binds only retinoic acid at specific sites within the nucleus, which may contribute to vitamin A-directed differentiation in epithelial tissue. CRABP1 is constitutively expressed and is thought to have different functions in the cell than the related CRABP2. CRABP1 forms a beta-barrel structure which accommodates hydrophobic ligands in its interior. Loss of CRABP1 function as a result of hypermethylation of its promoter leads to pathogenesis of papillary thyroid carcinoma. Furthermore, frequent methylation-associated silencing of CRABP1 is linked to esophageal squamous-cell carcinoma.

Apoptosis-Inducing Factor, Mitochondrion-Associated, 1 (AIFM1) is a mitochondrial protein which translocates to the nucleus once apoptosis has been initiated. AIFM1 causes DNA fragmentation and chromatin condensation and also triggers the release of cytochrome c and caspase-9 from mitochondria. Bcl-2 overexpression prevents the release of AIFM1 from mitochondria, but doesn’t block its apoptogenic activity.

Transthyretin (TTR) is a circulating and abundant tetramer, which functions as a carrier protein of thyroid hormone and retinol binding protein. It is primarily produced in the liver, but also in the brain and eye. Mutations in the TTR gene cause the protein to dissociate into monomers that after misfolding assemble into amyloid fibrils deposits in a variety of organs. TTR is also the only gene known to be associated with familial TTR amyloidosis. The diseases that originate from mutations in the TTR gene include amyloidotic polyneuropathy, euthyroid hyperthyroxinaemia, amyloidotic vitreous opacities, cardiomyopathy, oculoleptomeningeal amyloidosis, meningocerebrovascular amyloidosis, carpal tunnel syndrome, etc.

RAB5A is a member of RAS oncogene family. The small GTPase, RAB5A is a crucial regulatory component of the endocytic pathway. Activation of RAB5A is mediated by GDP-GTP exchange factors (GEFs) that generate the Rab5-GTP complex). RAB5A is required for the fusion of plasma membranes and early endosomes.

EPHA2 is a member of the ephrin receptor subfamily of the protein-tyrosine kinase family. EPH and EPH-related receptors are implicated in mediating developmental events, particularly in the nervous system. Receptors in the EPH subfamily typically have a single kinase domain and an extracellular region containing a Cys-rich domain and 2 fibronectin type III repeats. The ephrin receptors are divided into two groups based on the similarity of their extracellular domain sequences and their affinities for binding ephrin-A and ephrin-B ligands. The EPHA2 gene encodes a protein that binds ephrin-A ligands. Mutations in the EPHA2 gene are the origin of certain genetically-related cataract disorders.

PSMA is a cancer antigen that is widely expressed as a noncovalent homodimer on the surface of prostate cancer cells, rather than on normal cells, therefore it is an interesting target to image prostate tissues when being used with radioactive antibodies. PSMA is expressed on the surface of novel blood vessels that nourish a broad range of other solid tumors. PSMA is a type II membrane protein with folate hydrolase activity produced by prostatic epithelium. PSMA expression is found in extraprostatic tissues, including small bowel and brain.

A fusion tag called FLAG consists of eight amino acids (AspTyrLysAspAspAspAspLys) including an enterokinase-cleavage site. FLAG is specifically designed for immunoaffinity chromatography. It allows elution under non-denaturing conditions. Several antibodies against this peptide have been developed. One antibody denoted as M1 binds the peptide in the presence of bivalent metal cations preferably Ca(+). Elution is effected by chelating agents. Another strategy is competitive elution with excess of free Flag Peptide. The FLAG peptide purifies and detects recombinant fusion proteins. FLAG peptide is useful in Western blotting, immunocytochemistry, immunoprecipitation, flow cytometry, protein purification, and in the study of protein-protein interactions, cell ultrastructure, and protein localization. Flag peptide is a hydrophilic tag which significantly improves the detection and purification of recombinant fusion proteins.

Thioredoxin-2 is a low molecular weight redox protein. TRX2 contains a redox active disulfide/dithiol group within the conserved Cys-Gly-Pro-Cys active site. The TXN2 is involved in the regulation of the mitochondrial membrane potential and in protection against oxidant-induced apoptosis. Upon stimulation of Fas, TXN2 mediates denitrosylation of mitochondria-associated caspase-3, a process required for caspase-3 activation, and promoted apoptosis.
TRX2 is important at low oxidative stress conditions.
MTRX is involved in the regulation of the mitochondrial membrane potential and cell death. Mitochondrial thioredoxin plays an important roles in protection against oxidant-induced apoptosis. Thioredoxin1 and thioredoxin2 have opposed regulatory functions on hypoxia-inducible factor-1alpha.

FKBP4 is part of the immunophilin protein family, which takes part in immunoregulation and necessary cellular processes concerning protein folding and trafficking. FKBP4 is a cis-trans prolyl isomerase that connects to the immunosuppressants FK506 and rapamycin. FKBP4 has high structural and functional similarity to FKBP1A, though, FKBP4 does not have immunosuppressant activity when complexed with FK506. FKBP4 interacts with interferon regulatory factor-4 and is involved in immunoregulatory gene expression in B and T lymphocytes. FKBP4 is known to connect with phytanoyl-CoA alpha-hydroxylase. FKBP4 associates with HSP90 & HSP70 thus takes part in the intracellular trafficking of hetero-oligomeric forms of the steroid hormone receptors. FKBP4 highly associates with adeno-associated virus type 2 vectors (AAV) resulting in a considerable increase in AAV-mediated transgene expression in human cell lines. FKBP4 is involved in the optimal use of AAV vectors in human gene therapy.

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.

BCL2-associated athanogene 2 (BAG2) belongs to the Bag family of proteins. BAG2 is a chief component of the HSC 70/CHIP chaperone-dependent ubiquitin ligase complex and acts to upset CHIP-mediated ubiquitylation. BAG proteins compete with Hip for attaching to the Hsc70/Hsp70 ATPase domain and promote substrate discharge. All the BAG proteins have a roughly 45 amino acid BAG domain by the C-terminus but vary clearly in their N-terminal regions. The BAG domains of BAG1, BAG2, and BAG3 act together expressly with the Hsc70 ATPase domain in vitro and in mammalian cells. All three proteins attach with high affinity to the ATPase domain of Hsc70 and obstruct its chaperone activity in a Hip-repressible manner.

BID accession number NP_001187 is a pro-apoptotic Bcl-2 protein having only the BH3 domain. In reaction to apoptotic signaling, BID interacts with another Bcl-2 family of cell death regulators, called Bax, they form a heterodimer resulting to the insertion of Bax into the outer mitochondrial membrane. Bax induces the opening of the mitochondrial voltage-dependent anion channel which leads to the release of cytochrome c and other pro-apoptotic factors from the mitochondria resulting in activation of caspases. BID is a mediator of mitochondrial damage induced by caspase-8 (CASP8). CASP8 cleaves BID, and the COOH-terminal part translocates to mitochondria where it triggers cytochrome c release. The major proteolytic product p15 BID releasea cytochrome c. Isoform 1, Isoform 2 and Isoform 4 induce ice-like proteases and apoptosis while Isoform 3 does not induce apoptosis.

CASQ2 belongs to the calsequestrin family and is localized to the sarcoplasmic reticulum in cardiac and slow skeletal muscle cells. CASQ2 is a calcium binding protein that stores calcium for muscle function. The discharge of calcium bound to CASQ2 through a calcium release channel activates muscle contraction. CASQ2 binds 40 to 50 moles of calcium. CASQ2 mutations result in stress-induced polymorphic ventricular tachycardia, also called catecholaminergic polymorphic ventricular tachycardia 2 which is known fir its bidirectional ventricular tachycardia that causes cardiac arrest.

SARS Coronavirus is an enveloped virus containing three outer structural proteins, namely the membrane (M), envelope (E), and spike (S) proteins. Spike (S)-glycoprotein of the virus interacts with a cellular receptor and mediates membrane fusion to allow viral entry into susceptible target cells. Accordingly, S-protein plays an important role in virus infection cycle and is the primary target of neutralizing antibodies.It has recently been shown that SARS is caused by a human coronavirus. Human coronaviruses are the major cause of upper respiratory tract illness in humans, such as the common cold. Coronaviruses are positive-stranded RNA viruses, featuring the largest viral RNA genomes known to date (27-31 kb). The first step in coronavirus infection is binding of the viral spike protein, a 139-kDa protein, to certain receptors on host cells. The spike protein is the main surface antigen of the coronavirus. The most prominent protein in the culture supernatants infected with SARS virus is a 46 kDa nucleocapsid protein. This suggests that the nucleocapsid protein is a major immunogen that may be useful for early diagnostics.

Troponin I, (TNNI1) is a member of the troponin I family. Troponin complex has 3 subunits, TNNI1 known as the inhibitory Subunit which prevents the actin-myosin interactions and thus mediating striated muscle relaxation. TNNI1 combines with tropomyosin and regulates calcium sensitivity of striated muscles by structural modifications in actin-myosin complexes.

Beta 2 microglobulin is an 11 kDa protein associated with the outer membrane of many cells including lymphocytes. It is the small subunit of the MHC class I molecule. Association with beta 2-microglobulin is generally required for the transport of class I heavy chains from the endoplasmic reticulum to the cell surface. Beta 2 microglobulin associates with class I-like molecules such as CD1 and Qa as well as with the alpha chain of MHC class I molecules. Very limited amounts of MHC class I molecules can be found on the surface in the absence of Beta 2 microglobulin. CD8 T cells cannot develop in the absence of MHC class I.
Beta 2-microglobulin is present in small amounts in serum, csf, and urine of normal people, and to a much greater degree in the urine and plasma of patients with tubular proteinaemia, renal failure, or kidney transplants. Human Beta 2 microglobulin levels can rise either because its rate of synthesis has increased (e.g. in AIDS, malignant monoclonal plasma cell dyscrasia, solid tumors and autoimmune disease) or because of impaired renal filtration (e.g. due to renal insufficiency, graft rejection or nephrotoxicity induced by post-transplantation immunosuppressive therapy). Beta-2 microglobulin levels might also be elevated in multiple myeloma and lymphoma cases. Dialysis-related amyloidosis develops after a long-term hemodialysis, it can aggregate into amyloid fibers that deposit in joint spaces.

The T1/Leu1/CD5 molecule, a human T-cell surface glycoprotein of relative molecular mass (Mr) 67,000, has been implicated in the proliferative response of activated T cells and in T-cell helper function. Ly1 is the murine homolog. (In the mouse, lymphocyte surface antigens that are markers for function have been identified. Allelic forms are known and chromosomal assignment of the loci has been achieved. Ly1 is on mouse chromosome 19. Ly2 and Ly3 are on mouse chromosome 6. Ly5 is on mouse chromosome 1. Ly6 is on mouse chromosome 15.

CD21 is expressed strongly on mature B cells, follicular dentritic cells and weakly on immature thymocytes and T lymphocytes. In B-cell ontogeny, CD21 appears after the pre-B-stage, is maintained during peripheral B-cell development and is lost upon terminal differentiation into plasma cells. CD21 expression is also gradually lost after stimulation of B cells in vitro. CD21 functions as receptor for C3d, C3dg and iC3b Complement components, for EBV and for IFNalpha. CD21 binds to CD23 and associates with CD19, CD81 and Leu13 to form a large signal-transduction complex involved in B cell activation.

EPCAM is a carcinoma-associated antigen and belongs to a family which includes at least 2 type I membrane proteins. The EPCAM protein has a role in embryonic stem cells proliferation and differentiation. EPCAM is used as a target for immunotherapy treatment of human carcinomas. EPCAM is expressed on most normal epithelial cells and gastrointestinal carcinomas and acts as a homotypic calcium-independent cell adhesion molecule. Epithelial cell adhesion molecules (EPCAM) can act as a physical homophilic interaction molecule between intestinal epithelial cells (IECs) and intraepithelial lymphocytes (IELs) at the mucosal epithelium for supplying immunological barrier as a first line of defense against mucosal infection. EPCAM gene mutations result in congenital tufting enteropathy.