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CD44 is a cell-surface glycoprotein that plays a role in cell-cell interactions, cell adhesion and migration. CD44 is a receptor for hyaluronic acid and also interacts with other ligands, such as osteopontin, collagens, and matrix metalloproteinases. CD44 participates in a wide variety of cellular functions such as lymphocyte activation, recirculation and homing, hematopoiesis, and tumor metastasis. CD44 and CD49d are putative activity markers and CD44 a potential novel therapeutic target in multiple sclerosis. Increased CD44 antigen is associated with relapses in non-small cell lung cancers.

GSTP1 is a polymorphic gene encoding active, functionally different GSTP1 variant proteins that are believed to function in xenobiotic metabolism and have a part in susceptibility to cancer, and other diseases. GSTP1 is a glutathione S-transferase belonging to the pi class. GST family enzymes play a significant role in detoxification by catalyzing the conjugation of many hydrophobic and electrophilic compounds with reduced glutathione. Based upon the biochemical, immunologic and structural properties of the soluble GSTs they are grouped into 4 main classes: alpha, mu, pi, and theta. The GSTP1 enzyme acts by catalyzing the reaction of glutathione with an acceptor molecule to form a Sulfur-substituted glutathione. The reactions employing glutathione contribute the transformation of a broad range of electrophiles, including reactive products of lipid, protein, carcinogens, therapeutic drugs, environmental toxins, and products of oxidative stress.
The GSTP1 inactivation through CpG hypermethylation is frequent in pituitary adenomas and may be a factor in aggressive pituitary tumor behavior. GSTP1 is may be a transcriptional target of the p53 tumor suppressor gene. Single-nucleotide polymorphism in GSTP1 is linked to modified protein binding, which influence GSTP1's contribution to carcinogen and drug metabolism, and possibly disease pathogenesis and/or drug response. GST-pi might have central roles in proliferation of androgen-independent human prostate cancer cells.

Myeloid differentiation antigen Gr1 (Ly6G) is a GPI-anchored protein, which is briefly expressed on monocytes in the bone marrow. The level of the Ly6G expression in the bone marrow completely correlates with granulocyte differentiation and maturation. Ly6G ligation on murine neutrophils inhibits neutrophil recruitment, thus providing the first evidence of a function for the Ly6G molecule. Ly6G is seen primarily on neutrophils, also in a subgroup of eosinophils, differentiating pre-monocytes and plasmacytoid dendritic cells.

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.

CFLAR contains two death effector domains (DEDs) and a caspase-like domain. CFLAR may play a critical role between cell survival and cell death pathway in mammalian cells. CFLAR also interacts with adapter protein FADD and caspase-8 and -10, and potently inhibits apoptosis induced by all known death receptors DR3 (death receptor 3), TRAIL-R (TNF-related apoptosis-inducing ligand receptor) and TNFR1 (tumor necrosis factor receptor 1).

Tumor protein p53, a nuclear protein, plays an essential role in the regulation of cell cycle, specifically in the transition from G0 to G1. It is found in very low levels in normal cells, however, in a variety of transformed cell lines, it is expressed in high amounts, and believed to contribute to transformation and malignancy. p53 is a DNA-binding protein containing DNA-binding, oligomerization and transcription activation domains. It is postulated to bind as a tetramer to a p53-binding site and activate expression of downstream genes that inhibit growth and/or invasion, and thus function as a tumor suppressor. Mutants of p53 that frequently occur in a number of different human cancers fail to bind the consensus DNA binding site, and hence cause the loss of tumor suppressor activity. Alterations of the TP53 gene occur not only as somatic mutations in human malignancies, but also as germline mutations in some cancer-prone families with Li-Fraumeni syndrome.

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 (severe acute respiratory syndrome) is caused by a human coronavirus. Human coronaviruses are the major cause of upper respiratory tract illness, such as the common cold, in humans. 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 glycosilated spike protein (as well as the nucleocapsid protein) can be detected in infected cell culture supernatants with antisera from SARS patients.

TOLLIP is a ubiquitin-binding protein that interacts with several Toll-like receptor (TLR) signaling cascade components. TOLLIP regulates inflammatory signaling and is involved in interleukin-1 receptor trafficking and in the turnover of IL1R-associated kinase.

RAN Binding Protein 3, also known as RANBP3, is found in the nucleus and cytoplasm. RANBP3 which owns RanBD1 domain participates in nuclear export as part of a heteromeric complex. RANBP3 is also negatively regulates TGF-beta signaling by interacting with the R-SMAD proteins, SMAD2 and SMAD3.

Synaptobrevin 2 which is an 18 kDa integral membrane protein localized to the cytoplasmic surface of synaptic vesicle, consists of a proline-rich N-terminal region, a highly conserved hydrophilic domain, followed by a transmembrane anchor and a C-terminal. Synaptobrevin 2 is predominantly expressed in Langerhans islets and glomerular cells. The N-terminal domain of the protein (residues 1-89) forms a specific SNARE complex with the target membrane-associated t- or Q-SNAREs syntaxin 1 and SNAP-25.

C1QBP binds to the globular "heads" of c1q thus inhibiting c1 activation. C1QBP interacts with a wide range of ligands and is implicated in cell signaling. C1QBP associates with C1r and C1s in order to yield the first component of the serum complement system. C1QBP protein has been identified as the p32 subunit of pre-mRNA splicing factor SF2, as well as a hyaluronic acid-binding protein.
C1QBP is a new marker of tumor cells and tumor-associated macrophages/myeloid cells in hypoxic/metabolically deprived areas of tumors.
Mitochondrial C1QBP is a critical mediator of p14ARF-induced apoptosis.
C1QBP functions as a chemotactic factor for immature dendritic cells, and migration is mediated through ligation of both C1QBP and cC1qR/CR.
C1QBP overexpression successfully blocks mRNA accumulation from the adenovirus major late transcription unit (MLTU) and stimulates RNA polymerase II carboxy-terminal domain phosphorylation in virus-infected cells.
C1QBP binds with Hepacivirus core protein on CD8+ and CD4+ positive t-cells and inactivates lck and akt.

Cytokeratin 5 (KRT5) belongs to the keratin gene family. The type II cytokeratins are comprised of basic or neutral proteins which are arranged in pairs of heterotypic keratin chains coexpressed throughout differentiation of simple and stratified epithelial tissues. The type II cytokeratins are clustered in a region of chromosome 12q12-q13. The KRT5 type II cytokeratin is specifically expressed in the basal layer of the epidermis with family member KRT14. Mutations in these genes are linked with a complex of diseases termed epidermolysis bullosa simplex.

FUBP1 is a ssDNA binding protein which stimulates expression of c-myc in undifferentiated cells and activates the far upstream element (FUSE) of c-myc. Regulation of FUSE by FUBP happens by single-strand binding of FUBP to the non-coding strand. FUBP1 performs as an ATP-dependent DNA helicase.

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.

Immature Colon Carcinoma Transcript 1 (ICT1) functions as a codon-independent translation release factor that has lost all stop codon specificity and leads the termination of translation in mitochondrion in case of abortive elongation. The mature colon epithelium has 3 differentiated cell types which arise from a multipotent stem cell. ICT1 is involved in the hydrolysis of peptidyl-tRNAs which have been prematurely terminated and consequently in the recycling of stalled mitochondrial ribosomes. Digression from the normal maturation pathway by neoplastic transformation is assumed to originate in stem cells or their early descendants.

IL-7 is a cytokine important for B and T cell development. This cytokine and the hepatocyte growth factor (HGF) form a heterodimer that functions as a pre-pro-B cell growth-stimulating factor. This cytokine is found to be a cofactor for V(D)J rearrangement of the T cell receptor beta (TCRB) during early T cell development. This cytokine can be produced locally by intestinal epithelial and epithelial goblet cells, and may serve as a regulatory factor for intestinal mucosal lymphocytes. Knockout studies in mice suggested that this cytokine plays an essential role in lymphoid cell survival.

RAB7A belongs to the Ras superfamily of small Rab GTPases. RAB7A connects with the RIPL effector protein to regulator membrane trafficking from early to late endosome and to lysosomes. RAB7A can also regulate growth receptor endocytic trafficking, degradation, maturation of phagosome and autophagic vacuoles.

Microfibrillar-associated protein 4 (MFAP4) is a member of Fibrinogen protein family and contains 1 fibrinogen C-terminal domain. The MFAP4 protein has similarity to a bovine microfibril-associated protein. MFAP4 has binding specificities for both collagen and carbohydrate. MFAP4 is believed to be an extracellular matrix protein that is involved in cell adhesion or intercellular interactions. MFAP4 deletion was found in 30 of 31 Smith-Magenis syndrome (SMS) patients.

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.

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).

IL2-Ra is one of the three constituent subunits of the IL2 receptor. IL-2Ra is released into the serum after increased cellular expression such as increased activation of B and T cells. Clinical manifestations of IL2-Ra elevation include autoimmune conditions and some leukemias and lymphomas.

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.