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SGTA is a ubiquitously expressed protein that contains three TPR protein-protein interaction duplicates. SGTA takes part as a component of the androgen receptor (AR)-chaperone-cochaperone complex, functions as a cochaperone and participates in androgen signaling. SGTA binds directly to HSC70 and HSP70 and mediates their ATPase activity. SGTA gene encodes a protein that is able to interact with the chief nonstructural protein of parvovirus H-1 and 70-kDa heat shock cognate. In addition, SGTA interacts with Vpu and Gag from HIV-1, SARS-CoV accessory protein 7a, DNAJC5 and DNAJC5B. Since this transcript is expressed universally in several tissues, SGTA serves a housekeeping function. While being involved in apoptosis and androgen signaling, SGTA is a possible molecule for polycystic ovary syndrome, a disorder characterized by androgen excess, obesity and menstrual disturbances.

VAMP8 also called endobrevin, is the main component of a SNARE complex involved in the docking and fusion of synaptic vesicles with the presynaptic membrane. VAMP8 protein is involved in the regulatation of enzyme secretion in pancreatic acinar cells and plays a part in the abscission of the midbody during cell division, which leads to completely separate daughter cells. VAMP8 is essential for dense-granule secretion in platelets. VAMP8 is related with the perinuclear vesicular structures of the early endocytic compartment. VAMP8 interacts particularly with the soluble NSF-attachment protein (alpha-SNAP), through an VAMP8-containing SNARE complex.

Avidin is a tetrameric protein of 4 identical subunits (homotetramer) which can bind to biotin with a high degree of affinity and specificity. The estimated molecular weight of Avidin in its tetrameric form is between 66-69 kDa. Avidin is produced in the oviducts of birds, reptiles and amphibians and is subsequently deposited in the whites of their eggs. In the chicken egg white, avidin makes up roughly 0.05% of total protein (approximately 1.8 mg per egg). 10% of Avidin’s molecular weight is ascribed to carbohydrate content which is composed of 4-5 mannose and 3 N-acetylglucosamine residues. Avidin has at least three distinctive oligosaccharide structural type which are similar in structure and composition. The dissociation constant (KD) of avidin is approximately 10-15M, making it one of the strongest known non-covalent bonds.

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.

SPA17 is a protein present at the cell surface. SPA17 was characterized by its participation in the binding of sperm to the zona pellucida of the oocyte. The central portion of SPA17 has carbohydrate binding motifs and likely takes part in cell-cell adhesion functions such as immune cell migration and metastasis.

Signal-Regulatory Protein Alpha, SIRPA belongs to the signal-regulatory-protein (SIRP) family, as well as theimmunoglobulin super family. The members of the SIRP family are receptor-type transmembrane glycoproteins which areinvolved in the negative regulation of receptor tyrosine kinase-coupled signaling processes. SIRPA can bephosphorylated by tyrosine kinases. The phospho-tyrosine residues of this PTP have been shown to recruit SH2domain containing tyrosine phosphatases (PTP), and perform as substrates of PTPs. SIRPA take part insignal transduction mediated by a variety of growth factor receptors. CD47 has been shown to be a ligand forSIRPA.

Sprouty Homolog 4 (SPRY4) is an inhibitor of the receptor-transduced mitogen-activated protein kinase (MAPK) signaling pathway. SPRY4 is positioned upstream of RAS activation. SPRY4 protein functions include suppressing the EGFR-transduced MAPK signaling pathway as well as impairing the formation of GTP-Ras.

Protein A is a cell wall component produced by several strains of Staphylococcus aureus. The recombinant Protein A is genetically engineered protein and holds 5 IgG-binding regions of protein A. Recombinant Protein A functions basically the same as native Protein A and is perfect for purification of polyclonal or monoclonal IgG antibodies. Protein A binds to human IgG1, IgG2 and IgG4, mouse IgG2a, IgG2b and IgG3 and rat IgG2c. Protein A also binds to total IgG from rabbit, pig, dog, cat, and guinea pig.

Recombinant Protein A/G fusion protein joins IgG binding domains of both Protein A and Protein G.
Protein A/G includes four Fc binding domains from Protein A and two from Protein G, yielding a final mass of 50.4 kDa. The binding dependency to pH of Protein A/G lower than Protein A, but has the additive properties of Protein A and G together. Protein A/G binds to all subclasses of human IgG, making it helpful for purifying polyclonal or monoclonal IgG antibodies whose subclasses have not been identifieed. Protein A/G binds to IgA, IgE, IgM and IgD. Protein A/G binds to all subclasses of mouse IgG excluding mouse IgA, IgM or serum albumin. This permits Protein A/G to be used in purification and detection of mouse monoclonal IgG antibodies, with no interference from IgA, IgM and serum albumin. Mouse monoclonal antibodies normally have a stronger affinity to the chimeric Protein A/G than to either Protein A or Protein G. Protein A/G also has been used for purification of macaque IgG.

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.

Streptolysin-O is a sulfhydryl-activated toxin which causes cytolysis by forming pores in cholesterol containing host membranes. After binding to target membranes, the Streptolysin-O protein undergoes a major conformation change, leading to its insertion in the host membrane and creation of an oligomeric pore complex. Cholesterol may be needed for binding to host membranes, membrane insertion and pore formation. Streptolysin-O can be reversibly inactivated by oxidation.

Cartilage-associated protein (CRTAP) is a secreted protein localizing to the extracellular space which takes part in collagen post-translational modifications, extracellular fibril assembly and intracellular trafficking. CRTAP which is mainly expressed with predominant expression in articular chondrocytes is essential for efficient 3-hydroxylation of fibrillar collagen prolyl residues. Mutations in the gene encoding CRTAP might cause to autosomal recessive osteogenesis imperfecta (OI) type 7 and type 2B.

SIVA1, also referred to asApoptosis regulatory protein Siva isoform 1, is a death domain-containing proapoptotic protein. It is known as glucocorticoid-induced TNFR family-related gene, and also as an intracellular ligand of CD27, which are both members of the TNFR family expressed on lymphoid cells. There isn’t much known about the signalling pathway underlying the Siva-induced apoptosis.SIVA1 expression is modulated in multiple pathological processes.

Signal-Regulatory Protein Gamma (SIRPG) belongs to the signal-regulatory protein (SIRP) family whose members are receptor-type transmembrane glycoproteins which negatively regulate the receptor tyrosine kinase-coupled signaling processes. SIRPG is also a part of the immunoglobulin superfamily.

TRIM21 is a member of the tripartite motif (TRIM) family. The TRIM motif includes three zinc-binding domains, a RING, a B-box type 1 and a B-box type 2, and a coiled-coil region. The 52 kDa Ro protein is part of the RoSSA ribonucleoprotein, which includes a single polypeptide and one of four small RNA molecules. The RoSSA particle localizes to both the cytoplasm and the nucleus. Ro/SSA interacts with autoantigens in patients with Sjogren syndrome and systemic lupus erythematosus. Ribonucleoprotein particle is composed of a single polypeptide and one of four small RNA molecules. The RoSSA is present in all mammalian cells studied but has no known function. At least 2 isoforms are present in nucleated and red blood cells, and tissue specific differences in Ro/SSA proteins were identified.

Myxoma Resistance Protein 1 (MX1) is a member of the dynamin family and contains 1 GED domain. MX1 is an Interferon-induced dynamin-like GTPase with antiviral activity against rabies virus (RABV), vesicular stomatitis virus (VSV) and murine pneumonia virus (MPV). MX1 is ubiquitously expressed. MX1 is induced by type I and type III interferons.

MTPN is an ankyrin repeat protein, that stimulates protein synthesis and cardiomyocyte growth to commence cardiac hypertrophy by activating the NF-kappaB signaling cascade. Myotrophin participates in cerebellar morphogenesis and takes part in differentiation of cerebellar neurons, particularly of granule cells. High levels of MTPN are expressed in human dilated cardiomyopathic and ischemic hearts.

Frataxin is a mitochondrial iron binding protein that is part of the FRATAXIN family. Frataxin functions in regulating mitochondrial iron transport and respiration. The expansion of intronic trinucleotide repeat GAA results in Friedreich ataxia. Frataxin plays a role in iron homeostasis. Frataxin is an anti-apoptotic protein which prevents mitochondrial damage and reactive oxygen species (ROS) production.

Alpha 1-microglobulin (A1M) is a lipocalin superfamily member (kernal lipocalins). A1M is a low molecular weight protein component of plasma. A1M is distributed in plasma and extravascular compartments of all organs. Alpha-1 Microglobulin is found in mammals, birds, amphibians and fish. The primary sites of A1M synthesis are the liver and the kidney. Around the opening of the lipocalin pocket three lysyl residues are situated; those residues carry yellow-brown modification derived from the binding and degradation of heme and kynurenin (a tryptophan metabolite). A1-Microglobulin’s reductase and dehydrogenase have broad biological substrate specificity properties due to its’ free cysteine side-chain which is located in a flexible loop. Alpha-1-microglobulin is glycosylated by three separate carbohydrate chains: two complex carbohydrates which are N-linked to asparagines at residues 17 and 96, and the other simple carbohydrate which is O-linked to threonine at position 5. The carbohydrates comprise 22% of the total molecular mass of the protein. The glycosylation varies between species.
A1M exists in two forms- a free form and complexed to other macromolecules: in humans- complexed to immunoglobulin A (IgA), in rat- complexed to alpha-1-inhibitor-3. Free A1M is exceptionally heterogeneous in charge (therefore also known as protein HC), and is found tightly linked to a chromophore. The free Alpha-1-microglobulin is a monomeric protein composed of one 188 residue polypeptide and contains three cysteines, two of which (residues 75 and 173) form a conserved intra-molecular disulphide link. The chromophoric group is covalently bound to the free cysteine residue at position 34. A1M binds retinol as a major ligand, but this is probably distinct from its covalent chromophore.
Half of all human plasma A1M (approximately 0.03mg/ml) forms a 1:1 complex with about 5% of plasma immunoglobulin A. The resulting macromolecular complexes’ molecular weight is 200000, and a plasma concentration of 0.3mg/ml. The complex can exhibit both antibody activity and affect many of the biological actions of free Alpha-1-microglobulin.
Alpha-1-microglobulin was first discovered in pathological human urine.
It was suggested that A1M might be involved in tissue defense against reactive oxygen species, oxidation by heme and kynurenin. Evidence also suggests that A1M functions in the regulation of the immune system. Other functions include inhibition of stimulation of cultured lymphocytes by protein antigens; induction of cell division of lymphocytes, a mitogenic effect that can either be enhanced or inhibited by the action of other plasma components; inhibition of neutrophil granulocyte migration in vitro; and inhibition of chemotaxis.

Sorting nexin 3 (SNX3) belongs to the large family of hydrophilic proteins, which interact with various receptor types and are involved in intracellular trafficking. SNX3 interacts with phosphatidylinositol-3-phosphate, and is involved in protein trafficking. SNX3 comprises a distinct subgroup of nexins, which share less sequence similarity outside of the PX domain and have significantly different binding affinities for the tyrosine kinase receptors.

Troponin Complex is a heteromeric protein playing an important role in the regulation of skeletal and cardiac muscle contraction. It consists of three subunits, Troponin I, Troponin T and TroponinC. Each subunit is responsible for part of Troponin Complex function. E.g. Troponin I inhibits ATP-ase activity of acto-myosin.Troponin T and Troponin Iare presented in cardiac muscles in different forms than in skeletal muscles. Purified subunits of rcTnI, rcTnC and rcTnT are recomplexed in vitro under appropriate conditions.

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.

Energy Homeostasis Associated (ENHO) participates in glucose homeostasis maintenance and lipid metabolism. ENHO is expressed in the liver and the brain. The role of ENHO in obesity or diabetes is studied.

STUB1, is a cytoplasmic protein whose amino acid sequence is highly preserved across species. STUB1 interacts with the molecular chaperones Hsc70-Hsp70 and Hsp90 through its TPR domain, whereas its U-box domain contains its E3 ubiquitin ligase activity. STUB1 interaction with these molecular chaperones lead to in client substrate ubiquitylation and degradation by the proteasome. therefore, STUB1 acts to tilt the folding-refolding mechanism towards the degradative pathway, and it serves as a link between the two. STUB1 inhibits anchorage-independent cell growth and metastatic potential by degrading oncogenic proteins including SRC-3. Inhibition of tyrosine kinase activity of Her-2/neu by quercetin specifies an lateration in the Her-2/neu structure which promotes STUB1 recruitments and down-regulation of Her-2/neu. STUB1 recognizes and mediates degradation of toxic, oligomeric forms of alphaSyn.