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Streptavidin is a tetrameric protein secreted by Streptomyces avidinii which binds firmly to biotin. Streptavidin is wilyde 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.

TNFAIP3-interacting protein 1 (TNIP1) interacts with zinc finger protein A20/TNFAIP3 and inhibits TNF-induced NF-kappa-B-dependent gene expression by interfering with a RIP- or TRAF2-mediated transactivation signal. Furthermore, TNIP1 interacts with HIV-1 matrix protein and is packaged into virions and its overexpression can inhibit viral replication. TNIP1 can regulate matrix nuclear localization, both nuclear import of Preintegration complex (PIC) and export of GAG polyprotein and viral genomic RNA during virion production.

Major pollen allergen Cor a 1 (Cor a 1.0103) causes an allergic reaction in human. The Cor a 1 isoforms exhibit different antigenic and allergenic properties.

p59-Fyn is a member of the protein-tyrosine kinase oncogene family. p59fyn is a membrane-associated non-receptor protein tyrosine kinase that belongs to the Src-family of kinases. p59-Fyn encodes a membrane-associated tyrosine kinase which is implicated in the control of cell growth. p59-Fyn associates with the p85 subunit of phosphatidylinositol 3-kinase and interacts with the fyn-binding protein. The unique N-terminal domain of p59fyn interacts with the CD3 and eta chains of the TcR. p59fyn can bind other proteins (p82 and p116) through its SH2 and SH3 domains, which may act as substrates or regulators of fyn activity. p59fyn is highly expressed in brain suggesting that it may have a role in the sensory nervous network and in myelination at early stages of CNS formation. Distinct isoforms exist due to alternative splicing.

At least 23 different variants of IFN-alpha are known. The individual proteins have molecular masses between 19-26 kDa and consist of proteins with lengths of 156-166 and 172 amino acids. All IFN-alpha subtypes possess a common conserved sequence region between amino acid positions 115-151 while the amino-terminal ends are variable. Many IFN-alpha subtypes differ in their sequences at only one or two positions. Naturally occurring variants also include proteins truncated by 10 amino acids at the carboxy-terminal end.

Exodus-2 protein or CCL21 is a cytokine, part of the CC chemokines subgroup. Because of its 6 conserved residues of the cysteine amino acid (instead of the 4 residues we usually see in chemokines), the protein is also named 6Ckine and SLC (secondary lymphoid-tissue chemokine). The gene that codes for this protein is located on chromosome 9 in humans. The Exodus-2 is binding to the CCR7 receptor, which is a chemokine receptor located to the cell’s surface.

Glial cell-derived neurotrophic factor or GDNF is part of the GDNF group of ligands proteins. GDNF has a crucial part in numerous cell mechanisms such as neurite outgrowth, cell differentiation, cell survival and migration of cells. GDNF enhances neurons survival via GFRa receptors (mainly GFRa1). The mentioned neurons can die as a result from Parkinson's disease or ALS (amyotrophic lateral sclerosis). This protein takes part in the development of the spermatogenesis & kidney, also, it has a role in alcohol metabolism as ameliorating.

Prorelaxin H2 (RLN2) is a member of the insulin gene superfamily. This family which is produced by the ovary, targets the mammalian reproductive system to ripen the cervix, elongate the pubic symphysis and inhibit uterine contraction. It may also have other roles in boosting sperm motility, regulating blood pressure, controlling heart rate and releasing oxytocin and vasopressin. RLN2 is a peptide hormone linked to several therapeutically relevant physiological effects, including regulation of collagen metabolism and multiple vascular control pathways. The active form of the RLN2 protein consists of an A chain and a B chain linked by disulfide bonds.

ASS1 is involved in the urea cycle, which is a sequence of chemical reactions that is localized in liver cells. The urea cycle processes excess nitrogen that is generated as the body uses proteins. The surplus nitrogen is used to create a molecule called urea, which is excreted from the body in urine.

rGFP, also known as Green Fluorescent Protein, is a protein produced by the jellyfish (Aequorea Victoria) that produces bioluminescence in the green zone of the noticeable spectrum. Green Fluorescent Protein is a useful and ubiquitous instrument for producing chimeric proteins, where it functions as a fluorescent protein tag. rGFP is expressed in most known cell types and is used as a noninvasive fluorescent marker in living cells and organisms. Green Fluorescent Protein permits a broad range of applications where it has functioned as a cell lineage tracer, reporter of gene expression, or as a measure of protein-protein interactions.

Galectin-2 or LGALS2 is a protein, part of the galectin proteins family. The galectin proteins family holds galectin proteins family lectins that mediates adhesion between cells or cells to ECM. This family also take part in pre-mRNA splicing, apoptosis & tumor progression. Galectin-2 induces apoptosis in T cells that are activated & binds to lymphotoxin-a, also can implicatate on myocardial infarction. LGALS2 from human and mouse share about 65% amino acid sequence resemblance.

The scaffolding protein encoded by the CAV1 gene is the key component of the caveolae plasma membranes found in most cell types. Cholesterol is vital for caveolae formation and maintenance, and caveolae structure is highly sensitive to cholesterol depletion or treatment with cholesterol binding drugs. CAV1 can tightly and specifically bind free cholesterol and artificial cholesterol containing vesicles. Caveolin 1 links integrin subunits to the tyrosine kinase FYN, which is an initiating step in coupling integrins to the Ras-ERK pathway and promoting cell cycle progression. CAV1 is a tumor suppressor gene candidate and a negative regulator of the Ras-p42/44 mitogen-activated kinase. Caveolin 1 and caveolin 2 are positioned next to each other on chromosome 7 and express co-localizing proteins which form a stable hetero-oligomeric complex cascade. Mutations in the CAV1 gene are linked to Berardinelli-Seip congenital lipodystrophy.

Endothelial cells express three different vascular endothelial growth factor (VEGF) receptors, belonging to the family of receptor tyrosine kinases (RTKs). They are named VEGFR-1 (Flt-1), VEGFR-2 (KDR/Flk-1), VEGFR-3 (Flt-4). Their expression is almost exclusively restricted to endothelial cells, but VEGFR-1 can also be found on monocytes, dendritic cells and on trophoblast cells. The flt-1 gene was first described in 1990. The receptor contains seven immunoglobulin-like extracellular domains, a single transmembrane region and an intracellular splited tyrosine kinase domain. Compared to VEGFR-2 the Flt-1 receptor has a higher affinity for VEGF but a weaker signaling activity. VEGFR-1 thus leads not to proliferation of endothelial cells, but mediates signals for differentiation. Interestingly a naturally occuring soluble variant of VEGFR-1 (sVEGFR-1) was found in HUVE supernatants in 1996, which is generated by alternative splicing of the flt-1 mRNA. The biological functions of sVEGFR-1 still are not clear, but it seems to be an endogenous regulator of angiogenesis, binding VEGF with the same affinity as the full-length receptor.

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.

FKBP1A is a 12kDa protein initialy discovered onin immune cells on the basis of its capability to bind and mediate the intracellular effect of the immunosuppressant FK506. FKBP1A is also known to mediate the action of Rapamycin-immunosuppressive agent. FKBP1A is part of the family of immunophilins, which have in common high affinity for immunosuppressant drugs and a peptidyl-prolyl cis-trans isomerase (PPIase). Activity which participates in folding of proline-containing protein. In the absence of immunosuppressive ligands, FKBP1A is involved in intracellular calcium regulation by associating with 3 types of Ca2+ release channel complexes: skeletal ryanodine receptors, cardiac ryanodine receptors and the inositol 1,4,5-triphosphate receptor. FKBP1A also interact with TGF-b type I receptor exerting an inhibitory effect on the TGF-b signaling pathway. FKBP12 plays a role in modulation of ryanodine receptor isoform-1 (ryr-1), a component of the calcium release channel of skeletal muscle sarcoplasmic reticulum. FKBP1A increase the folding of proteins and catalyzes the cis-trans isomerization of proline imidic peptide bonds in oligopeptides.

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.

Integrins are heterodimeric integral membrane proteins composed of an alpha chain and a beta chain. This I-domain containing alpha integrin combines with the beta 2 chain (ITGB2) to form a leukocyte-specific integrin referred to as macrophage receptor 1 ('Mac-1'), or inactivated-C3b (iC3b) receptor 3 ('CR3'). The alpha M beta 2 integrin is important in the adherence of neutrophils and monocytes to stimulated endothelium, and also in the phagocytosis of complement coated particles. Integrin alpha-m/beta-2 is implicated in various adhesive interactions of monocytes, macrophages and granulocytes as well as in mediating the uptake of complement-coated particles. CD-11b is identical with cr-3, the receptor for the ic3b fragment of the third complement component. CD-11b probably recognizes the r-g-d peptide in c3b. Integrin alpha-m/beta-2 is also a receptor for fibrinogen, factor x and icam1. it recognizes p1 and p2 peptides of fibrinogen gamma chain.

E-Selectin belongs to a family of divalent cation-dependent carbohydrate-binding glycoproteins or adhesion molecules. CD62E is expressed on the surface of endothelial cells and mediates the interaction of leukocytes and platelets with endothelial cells during an inflammatory response. CD62E is found in cytokine-stimulated endothelial cells and is accountable for the accumulation of blood leukocytes at sites of inflammation by mediating the adhesion of cells to the vascular lining. It demonstrates structural features such as the existence of lectin- and EGF-like domains followed by short consensus repeat (SCR) domains that contain 6 conserved cysteine residues. E-Selectin participates in the interaction between leukocytes and the endothelium and appears to be involved in the pathogenesis of atherosclerosis.

SPON1 is a cell adhesion protein which take part in the regulation of protein binding activity, regulation of protein processing and regulation of amyloid precursor protein catabolic mechanism. SPON1 is found in the extracellular space and it co-localizes with collagen-containing extracellular matrix. SPON1 stimulates the attachment of spinal cord and sensory neuron cells and the outgrowth of neurites in vitro.

Collagen, a major component of the extracellular matrix, is a fibrous protein that provides tensile strength to tissues giving them structural integrity. Collagen and its derivative, gelatin, have been widely used in medical, pharmaceutical and consumer products for more than 100 years. The supply of these materials, created from animal remains, is both abundant and inexpensive. However, most formulations are not highly purified and have the potential to cause an inflammatory reaction in some product users. In addition, concerns have been raised over the last several years about the potential for contamination of bovine products with the agent that causes mad cow disease and its human variant, Creutzfeldt-Jakob Disease. Animal collagens are subject to extensive modifications that continue over the life of the molecule in the extracellular space. These differences influence both the extractability of collagens from tissue and the biophysical characteristics of these collagens. As a result, collagens isolated from tissues exhibit significant lot-to-lot variability and, as bulk materials, are often analytically intractable. Products that contain animal-derived collagen can induce potentially harmful inflammatory or immune responses in humans and pose risk of contamination with viruses or prions, potentially life-threatening pathogens. Recombinant collagens are essentially identical to the native collagen protein thereby reducing the risk of inflammation, immune response, and disease as compared to animal-sourced collagen.

Bivalirudin directly inhibits thrombin by specifically binding as well to the catalytic site and to the anion-binding exosite of circulating and clot-bound thrombin. Bivalirudin is a specific and reversible direct thrombin inhibitor.
Thrombin, which is a serine protease, plays a central role in the thrombotic process; it cleaves fibrinogen into fibrin monomers and activates Factor XIII to Factor XIIIa, allowing fibrin to develop a covalently cross-linked structure which stabilizes the thrombus. Thrombin also activates Factors V and VIII, which promotes further thrombin generation, activates platelets, stimulating aggregation and granule release.