943 Risultati per: "AbFrontier"

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Thioredoxins (Trx) are small, multi-functional proteins with oxidoreductase activity and are ubiquitous in essentially all living cells. Trx contains a redox-active disulfide/ dithiol group within the conserved Cys-Gly-Pro-Cys active site. The two cysteine residues in the conserved active centers can be oxidized to form intramolecular disulfide bonds (1). Reduction of the active site disulfide in oxidized Trx is catalyzed by Trx reductase with NADPH as the electron donor. The reduced Trx is a hydrogen donor for ribonucleotide reductase, the essential enzyme for DNA synthesis, and a potent general protein disulfide reductase with numerous functions in growth and redox regulations (2). Specific protein disulfide targets for reduction by Trx include protein disulfide–isomerase (PDI) (3) and a number of transcription factors such as p53 (4), NF-kB (5) and AP-1 (T1-151). Trx is also capable of removing H2O2, particularly when it is coupled with either methionine sulfoxide reductase or several isoforms of peroxiredoxins (6-7).

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The p90 ribosomal S6 kinases (RSKs) comprise a family of serine/threonine kinases that lie at the terminus of the ERK pathway. In humans, the RSK family consists of four isoforms (RSK1 to -4). RSK family members are unusual among serine/threonine kinases in that they contain two distinct kinase domains, both of which are catalytically functional. Theses kinase dimains are activated in a sequential manner by a series of phosphorylations. RSK regulates gene expression via association and phosphorylation of transcriptional regulators including c-Fos, estrogen receptor, NFkappaB/IkappaB α, cAMP-response element-binding protein (CREB).
ERK activates the C-terminal kinase of RSK, leading to activation of the N-terminal kinase. Members of the RSK family are present in the cytoplasm as well as the nucleus. Addition of growth factor to the cells results in the activation of both cytosolic and nuclear RSK and the translocation of the cytosolic RSK into the nucleus upon activation. The activation and nuclear translocation of RSK result in phosphorylation and activation of transcription factors.

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Enolase (2-phosphogly-cerate hydrolyase or phosphopyruvate hydrates) is a glycolytic enzyme that catalyzes the dehydration and conversion of 2-phosphoglycerate to phosphoenolpyruvate. It comprises three distinct subunits, α, β and γ. The γγ and αγ dimeric forms of enolase, referred to as neuron-specific enolase(NSE), are localized mainly in neurons and neuroectodermal tissue. NSE has a high stability in biological fluids and can easily diffuse to the extracellular medium and cerebrospinal fluid(CSF) when neuronal membranes are injured. NSE is used clinically as a sensitive and useful marker of neuronal damage in several neurological disorders including stroke, hypoxic brain damage, status epilepticus, Creutzfeldt-Jakob disease, and herpetic encephalitis.

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Ataxia telangiectasia mutated (ATM) is a serine/threonine-specific protein kinase that is activated by DNA double-strand breaks. It phosphorylates several key proteins that initiate activation of the DNA damage checkpoint, leading to cell cycle arrest, DNA repair or apoptosis. Several of these targets are p53, CHK2, BRCA1, and H2AX.
ATM triggers the G1/S checkpoint; ATR (Ataxia telangiectasia and Rad3-related) prevents G1/S stasis. In this single point in the cell cycle, it would appear that ATM and ATR function in opposition to one another.
Ataxia telangiectasia (AT) is a rare neurodegenerative, autosomal recessive disorder characterized by chromosome instability, radiosensitivity, immunodeficiency and a predisposition for cancer.
The ATR (ATM and Rad3-related) kinase and its downstream effector kinase, Chk1, are central regulators of the replication checkpoint. Loss of these checkpoint proteins causes replication fork collapse and chromosomal rearrangements. ATR are thought to be master controllers of cell cycle checkpoint signaling pathways that are required for cell response to DNA damage and for genome stability.

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Anti-DUSP28 Mouse Monoclonal Antibody [clone: AF16B7]

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Insulin receptor substrate (IRS) proteins play a central role in maintaining basic cellular functions such as growth and metabolism through insulin/insulin like growth factor (IGF) signaling. Four members (IRS-1, IRS-2, IRS-3, IRS-4) of this family have been identified which differ in their subcellular distribution and interaction with SH2 domain proteins. After phosphorylation by activated receptors, these intracellular signaling molecules recruit various downstream effector pathways including phosphatidylinositol 3-kinase, tyrosine protein phosphatase SHPTP-2, and several smaller adapter molecules such as the growth factor receptor-binding protein Grb-2.
IRSs are also thought to be able to induce malignant transformation.

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Glutaredoxin (Grx), also known as thiol transferase, is a small heat-stable oxidoreductase. Grxs form part of the glutaredoxin system, comprising NADPH, GSH and glutathione reductase, which transfers electrons from NADPH to glutaredoxins via GSH (1). First recovered in E.coli as GSH-dependent hydrogen donors for ribonucleotide reductase, Grx catalyzes GSH-disulfide oxido-reductase via two redox-active cysteine residues (2). The active sequence (Cys-Pro-Tyr-Cys) is conserved in a variety of species. The 12 kDa dithiol protein has a role in reduction of mixed disulfides in cells exposed to oxidative stress (3).

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Transthyretin(TTR), generally called prealbumin, is a plasma protein that plays an important role in physiology such as a transporter of hormone thyroxine and retinal-binding protein. After produced primarily in the liver, TTR is excreted into the plasma. TTR represents a disproportionate fraction (25%) of CSF protein, prompting the suggestion that it is either selectively transported across the blood-CSF barrier or synthesized de novo within the central nervous system.
Transthyretin is a constituent found to the neuritic plaques, neurofibrillary tangles, and microangiopathic lesions of senile cerebral amyloid. It has been reported that more than 40 different mutations in the TTR gene associated with amyloid deposition.

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NCK1 is one of the adaptor proteins which mediate specific protein-protein interactions in signaling processes. Adaptor proteins usually contain several domains like SH2 (Src homology 2) and SH3 which allow specific interactions with other specific proteins.
NCK1 and NCK2 showing high sequence identity (68%) have three SH3 domains and a C-terminal SH2 domain. Both of them bind receptor tyrosine kinases such as PDGFR and other tyrosine phosphorylated
proteins via their SH2 domains. Various molecules which interact with SH domains of Nck and regulate signaling process of actin cytoskeleton reorganization have been identified. Ncks are thought to have important functions in the development of mesodermal structures during embryogenesis, linked to a role in cell movement and cytoskeletal reorganization.
Nck also have a function in modulating mRNA translation at the level of initiation by interacting eukayotic initiation factor 2 (eIF2). Under the stressed conditions, protein synthesis is reduced by inhibiting the activity of eIF2 through the phosphorylation, transiently inhibiting recycling of eIF2
into its active form.

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Tubulin is a heterodimer consisting of α and β-tubulin subunits. It is nearly ubiquitous among eukaryotic cells. The α and β tubulins, which are each about 55 kDa MW, are homologous but not identical. α-β tubulin heterodimer is the basic building block of microtubules. This intracellular cylindrical filamentous structure is present in almost eukaryotic cells. Microtubules serve as structural supports and lines of transport within the cell, as well as serving a key role in mitosis

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Synaptotagmins(Syts) are a large gene family of synaptic vesicle integral membrane proteins. Syt functions as regulators of both exocytosis /endocytosis and is involved in neurotransmitter secretion from small secretory vesicles. 13 isoforms of Syt have been identified(SytI-XIII).
SynaptotagminVI is localized to the endoplasmic reticulum and/or Golgi-like perinuclear compartment. It may be important for trafficking and calcium signaling as it is specially expressed in non-neuronal tissues. Also SytVI is present in the acrosomal region of mammalian spermatozoa. The cytosolic domain of SytVI can abrogate exocytosis by competing with the endogenous protein for essential interactions with the fusion machinery involved in a acrosomal exocytosis.

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Transglutaminase(TGase) catalyses the crosslink of proteins by forming -(-glutamyl) lysine isopeptide bonds and requires the binding of Ca2+ for its activity. In mammals, eight distinct TGase isoenzymes have been identified. Tissue transglutaminase (tTGase), also known as TGase 2, has four distinct domains: N-terminal -sandwich, catalytic core and two C-terminal -barrel domains. tTGase may have a role in cell death, cell proliferation, cell differentiation, and receptor-mediated endocytosis. In the Alzheimer’s disease brain, the elevated tTGase activity is manifested by polymerization of a number of proteins, including A peptide, -amyloid precursor protein and the tau protein, with formation of neurofibrillary tangles.

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Coilin is a component of the nuclear Cajar(coiled) bodies (CBs) which are involved in the function or assembly/disassembly of nucleoplasmic snRNPs.
Human coilin is a 576-amino acid protein found enriched in CBs, but is also found in large amounts in the nucleoplasm.
Coilin is a constitutive phosphoprotein that is hyperphosphorylated during mitosis and it is thought that hyperphosphorylation triggers CB disassembly during cell replication. Self-interaction and localization have been shown to depend on the phosphorylation state of coilin.

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Protein Phosphatase 2A (PP2A) is a ubiquitous and conserved Serine/Threonine phosphatase and accounts for a large fraction of phosphatase activity in eukaryotic cells. PP2A plays an important role in cell cycle regulation, cell growth control, development, regulation of various signal transduction pathways, and cell mobility.
PP2A comprises A and B subunits which are regulatory and a catalytic C subunit. When the PP2A catalytic C subunit (36 kDa) associates with the regulatory A (65 kDa, PR65) and B subunits (PR55, PR56, PR72, PR93 etc), wide variety of heterotrimeric holoenzymes are produced with distinct functions and characteristics. The different association of the subunits give PP2A large regulatory flexibility and differential substrate specificity. The A subunit exists as two isoforms ( α and β ) as does the C subunit, whereas the B subunits fall into three families designated B, B' (also called B56), and B''. The A subunit is the scaffold required for the formation of the heterotrimeric complex and the binding of A subunit alters the enzymatic activity of the catalytic subunit, even if the B subunit is absent.

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Component of the MRN complex, which plays a central role in double-strand break (DSB) repair, DNA recombination, maintenance of telomere integrity and meiosis. The complex possesses single-strand endonuclease activity and double-strand-specific 3'-5' exonuclease activity, which are provided by MRE11A. RAD50 may be required to bind DNA ends and hold them in close proximity. This could facilitate searches for short or long regions of sequence homology in the recombining DNA templates, and may also stimulate the activity of DNA ligases and/or restrict the nuclease activity of MRE11A to prevent nucleolytic degradation past a given point. The complex may also be required for DNA damage signaling via activation of the ATM kinase. In telomeres the MRN complex may modulate t-loop formation.

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Immunoglobulin M (IgM) forms polymers where multiple immunoglobulins are covalently linked together with disulfide bonds, normally as a pentamer and the J chain is attached to most pentamers. It has a large molecular mass of approximately 900 kD. Due to its polymeric nature, IgM possesses high avidity, and is particularly effective at complement activation. It is sometimes called a "natural antibody", but it is likely that the antibodies arise due to sensitization in the very young to antigens that are naturally occurring in nature. IgM is the first immunoglobulin expressed by mature B cells. IgM antibodies appear early in the course of an infection and usually do not reappear after further exposure. IgM antibodies do not pass across the human placenta. These two biological properties of IgM make it useful in the diagnosis of infectious diseases. Demonstrating IgM antibodies in patients serum indicates recent or in serum from a neonate intrauterine infection such as congenital rubella.

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Retinol binding protein (RBP), a 21kDa single-chain glycoprotein, is the primary plasma transport protein for retinol (vitamin A1). RBP solubilizes the water-insoluble retinol and works as a vehicle for transport to the target organs, and it may also protect the bound retinol from oxidative damage in the plasma. The circulating RBP binds to another protein called transthyretin (TTR), a 55-kDa plasma thyroxine binding protein. Such protein-protein complex formation is thought to prevent glomerular filtration of low molecular mass RBP. Serum levels of RBP are useful in the detection of liver disease, protein-calorie malnutrition, and vitamin A deficiencies. In addition, the determination of RBP serum levels has been shown to be important in the mediation of antitumor effects.

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The mammalian thioredoxin reductases (TrxRs) are a family of selenocysteine-containing pyridine nucleotide-disulfide oxido-reductases. All the mammalian TrxRs are homologous to glutathione reductase with respect to primary structure including the conserved redox catalytic site (-Cys-Val-Asn-Val-Gly-Cys-) but distinctively with a C-terminal extension containing a catalytically active penultimate selenocysteine (SeCys) residue in the conserved sequence(-Gly-Cys-SeCys-Gly). TrxR is homodimeric protein in which each monomer includes an FAD prosthetic group, a NADPH binding site and a redox catalytic site. Electrons are transferred from NADPH via FAD and the active-site disulfide to C-terminal SeCys-containing redox center, which then reduces the substrate like thioredoxin. The members of TrxR family are 55 – 58 kilodalton in molecular size and composed of three isoforms including cytosolic TrxR1, mitochondrial TrxR2, and TrxR3, known as Trx and GSSG reductase (TGR). TrxR plays a key role in protection of cells against oxidative stress and redox-regulatory mechanism of transcription factors and various biological phenomena (1).

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Superoxide dismutase (SOD) is an antioxidant enzyme involved in the defense system against reactive oxygen species (ROS). SOD catalyzes the dismutation reaction of superoxide radical anion (O2-) to hydrogen peroxide, which is then catalyzed to innocuous O2 and H2O by glutathione peroxidase and catalase. Several classes of SOD have been identified. These include intracellular copper, zinc SOD (Cu, Zn-SOD/SOD-1), mitochondrial manganese SOD (Mn-SOD/SOD-2) and extracellular Cu, Zn-SOD (EC-SOD/SOD-3) (1). SOD1 is found in all eukaryotic species as a homodimeric 32 kDa enzyme containing one each of Cu and Zn ion per subunit (2). The manganese containing 80 kDa tetrameric enzyme SOD2, is located in the mitochondrial matrix in close proximity to a primary endogenous source of superoxide, the mitochondrial respiratory chain (3). SOD3 is a heparin-binding multimer of disulfide-linked dimers, primarily expressed in human lungs, vessel walls and airways (4). SOD4 is a copper chaperone for superoxide dismutase (CCS), which specifically delivers Cu to copper/zinc superoxide dismutase. CCS may activate copper/zinc superoxide dismutase through direct insertion of the Cu cofactor.

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Sequential activation of protein kinases within the MAPK (mitogen-activated protein kinases) cascades is a common mechanism of signal transduction in many cellular processes. The ERK signaling cascade is a central MAPK pathway that plays a role in the regulation of various cellular processes such as proliferation, differentiation, development, learning, and survival. Mitogen-activated protein kinase kinases (MAPKK) phosphorylate MAPK. MEK (MAP kinase or ERK kinase) is the immediate upstream activator kinase of ERK.
MEK6 encodes a 334-amino acid protein with 82% identity to MKK3. MEK6 is highly expressed in skeletal muscle like many other members of this family, but in contrast to MKK3 its expression in leukocytes is very low. The human MEKs (MEK1, MEK2, MEK3) show remarkably different activity toward ERKl and ERK2. MEK2 is the most active ERK activator. MEK3 is inactive toward ERKl or ERK2. MEK3, MEK4, and MEK6 phosphorylate and activate p38 MAP kinase. The p38 mitogen-activated protein (MAP) kinase signal transduction pathway is activated by proinflammatory cytokines and environmental stress. Transcription factors such as ATF2 and Elk-1 are targets of the p38 MAP kinase signal transduction pathway.

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Anti-CREB-A Rabbit Polyclonal Antibody

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Anti-GAPDH Rabbit Polyclonal Antibody

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Anti-Neuroglobulin Rabbit Polyclonal Antibody

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The c-Jun N-terminal protein kinases (JNKs) are a family of serine/threonine protein kinases of the mitogen-activated protein kinase (MAPK) group. JNKs, which are essential regulators of physiological and pathological processes, are involved in several diseases including diabetes, atherosclerosis, stroke, and Parkinson's and Alzheimer's diseases. The JNK family consists of three isoforms; JNK1 and JNK2, which are ubiquitous, and JNK3, which is present primarily in the heart, brain and testis. Differential splicing and exon use yield 10 isoforms of JNK. JNK1 is an important mediator of insulin resistance associated with obesity, but it is also indispensable for the intact cytoarchitecture of the brain.

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Cyclin D3, ~34kDa, is a member of cyclin D family that promotes cell cycle progression to the DNA systhesis (S) phase. Cyclins complexed with cyclin-dependent kinases(CDKs) mediate phosphorylation of other proteins relevant to cell proliferation. D-type cyclins and their complexing CDKs phosphorylate the retinoblastoma gene product with influences transcription of growth-controlling genes. Cyclin D3 regulates cell proliferation during hematopoiesis, carcinogenesis, and may have function in the terminally differentiated cells. In recent studies, there is reports that cyclin D3 involves in multiple myeloma and malignant precursor T cells.

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Protein Phosphatase 2A (PP2A) is one of the major Ser/Thr phosphatases implicated in the regulation of many cellular processes including regulation of different signal transduction pathways, cell cycle progression, DNA replication, gene transcription and protein translation. The core structure comprises a 36 kDa catalytic subunit (PP2AC) and a 65 kDa regulatory subunit (PR65 or A subunit). Each PP2A subunit has at least two isoforms and the catalytic subunit, present in the α and β isoforms, share 97% homology. The differential association of all these subunits gives rise to an extensive subset of oligomeric holoenzymes. It is widely thought that PP2A exercises regulatory flexibility and differential substrate specificity through the specific association of the core dimer (PP2AD) with one of the three regulatory B subunits. Moreover, PP2A interacts with a still growing number of cellular and viral proteins and is regulated by posttranslational modifications.

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Platelet-derived growth factors (PDGFs) have been implicated in the control of cell proliferation, survival and migration. The PDGF family of growth factors consists of five different disulphide-linked dimers built up of four different polypeptide chains encoded by four different genes. Theses isoforms, PDGF-AA, PDGF-AB, PDGF-BB, PDGF-CC and PDGF-DD, act via two receptor tyrosine kinases, PDGF receptors α and β. Thus far, gene-targeting experiments have been attempted to create knockout mice deficient for PDGFR-α or PDGFR-β. Those mice, however, died either at the embryonic stage or several days after birth. Platelet-derived growth factor receptors, PDGFR-α and PDGFR-β, have five extracellular immunoglobulin-like domains and an intracellular tyrosine kinase domain. Upon binding a PDGF, the receptors form homo- and heterodimers. Dimerization of the receptors juxtaposes the intracellular part of the receptors, which allow phosphorylation in trans between the two receptors in the complex. These autophosphorylation provide docking sites for downstream signal transduction molecules. More than 10 different SH2–domain-containing molecules have been shown to bind to different autophosphorylation sites in the PDGF α- and β-receptors. There are signal transduction molecules with enzymatic activity, such as PI3-kinase, PLC-γ, Src, SHP-2, GAP, as well as adaptor molecules such as Grb2, Shc, Nck, Grb7 and Crk, and Stats. Each of the different partners recruited by the activated receptor initiates different signaling pathways, making possible a great variety of cellular response.

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Ferredoxin reductase is a ubiquitous flavoenzyme, containing noncovalently bound FAD as a prosthetic group (1). It plays a role in delivering NADPH or low potential one-electron donors such as ferredoxin and flavodoxin to redox-based metabolisms in plastids, mitochondria and bacteria (2). In mammals, ferredoxin reductase is loosely associated with the inner mitochondrial membrane and receives electrons from NADPH. These electrons are transferred to ferredoxin which shuttles electrons to cytochrome P450 in the adrenal cortex mitochondrial steroid hydroxylation systems (3).

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Transferrin (Tf) is a blood plasma protein for iron delivery. Transferrin functions to deliver iron to cells via a receptor-mediated endocytotic process as well as to remove toxic free iron from the blood and to provide an antibacterial, low-iron environment.
Tf protein contains 679 amino acid residues and has a molecular weight of ~79 kD, having 2 specific high affinity Fe(III) binding sites. The molecule is stabilized by 19 intra-chain disulfide bonds and is protected by three carbohydrate side chains. Although iron bound to transferrin is less than 0.1% (4 mg) of the total body iron, it is the most important iron pool, with the highest rate of turnover (25 mg/24 h).
When a Tf protein loaded with iron encounters a transferrin receptor (TfR) on the surface of a cell it binds to it and is consequently transported into the cell by endosomes. ATP-dependent proton pumps then force H+ ions into the endosomes reducing the pH to 5.5, thus promoting iron release and conformational change of the receptor enabling apo-transferrin to remain bound. The binding characteristics of the apo-Tf–TfR complex are such that the apo-Tf is released only once the complex reaches the cell surface.
Cells expressing large amounts of TfR are correspondingly competent in securing iron from Tf. Rapidly proliferating cells, as in malignancy, generally express TfR1 abundantly.
Several studies have shown a link between Tf polymorphism and susceptibility to disease. These include the rare autosomal recessive disorder atransferrinemia, cardiovascular disease (CVD) and Alzheimer’s disease.

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Transglutaminase(TGase) catalyses the crosslink of proteins by forming ε-(γ-glutamyl) lysine isopeptide bonds and requires the binding of Ca2+ for its activity. In mammals, eight distinct TGase isoenzymes have been identified. Tissue transglutaminase (tTGase), also known as TGase 2, has four distinct domains: N-terminal β-sandwich, catalytic core and two C-terminal β-barrel domains. tTGase may have a role in cell death, cell proliferation, cell differentiation, and receptor-mediated endocytosis. In the Alzheimer’s disease brain, the elevated tTGase activity is manifested by polymerization of a number of proteins, including Aβ peptide, β-amyloid precursor protein and the tau protein, with formation of neurofibrillary tangles.