Posts Tagged ‘Antibody catalog’

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The EEA1

Thursday, July 28th, 2011

EEA1, or Early Endosome Antigen 1 is a Rab5 effector essential for early endocytic membrane fusion. The EEA1 antibody is used in membrane trafficking and chaperone studies, and as an endosome marker tag. We at Novus Biologicals have a comprehensive antibody catalog of EEA1 products.

A homodimeric endosomal trafficking protein which was originally identified as an autoantigen, EEA1 antibody studies have shown the protein has a C-terminal FYVE zinc finger domain, which interacts with PtdIns[3]P (phosphatidylinositol 3-phosphate) enriched membrane vesicles, playing a vital role in the docking and fusion of early endosomes and penetrating bilayers.

In 2009, an EEA1 antibody study by researchers at the University of Colorado Denver School of Medicine showed that acidic conditions considerably increased the affinity for domain insertion into PtdIns3P-enriched early vesicle membranes. POPC/POPE/PtdIns(3)P vesicles bound to the FYVE domain of with a Kd of 49 nM at pH 6.0. At pH 8.0, the association was approximately 24 fold weaker. It is thought the decreased affinity was probably due to increased rate of dissociation of EEA1 from the bilayers. It was shown that lowering the pH enhanced RUFY1, Vps27p, Hrs and WDFY1 FYVE domain- interaction with the PtdIns(3)P of the vesicle membranes in vivo and in vitro, suggesting members of the FYVE finger family may be pH-dependent.

The results suggested PtdIns(3)P binding, and insertion of the domain into the vesicle membrane, was regulated by the adjacent His residues of the R(R/K)HHCRXCG motif. The electrostatic contacts and catalytic protonation state of the His residues stabilise the FYVE domain in its lipid-bound form, increasing membrane residence time and penetration. A mutation in either of the two residues nullifies this effect.

Antibody catalog researchers recently discovered a new subpopulation of early endosomes having Rab5 effector activity but lacking EEA1 interaction.

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The Ki67 Antibody in Cell Marker Studies

Monday, May 30th, 2011

The MK167, or Ki67 antibody recognizes a nuclear protein encoded by the MK167 gene. Ki167 is involved with RNA transcription and essential to cellular proliferation, being expressed by proliferating cells at all stages of the active cell cycle; it is exclusively used as a marker for cellular proliferation. The Ki67 antibody is a useful tool in cancer research and neuronal studies; however, MIB-1 antibodies also target the Ki67 marker and are preferred for clinical use.

During interphase, Ki67 is exclusively located in the nucleus, but relocates to the chromosome surface during cell division. The Ki67 antibody is a highly useful aid for determining the growth faction of cell populations in neoplasms and tumours, particularly those of the brain, prostate and breast. The faction of Ki67-positive tumour cells is called the Ki-67 labelling index, the value of which strongly correlates to the clinical development of cancer. Low Ki67 indices are indicative of low-grade tumours and a more favourable outcome for the patient.

For determining the Ki67 index in clinical applications, the Ki67 antibody has largely been superseded by MIB1 antibodies. This is because they were found to target the Ki67 antigen in the same way, but with the added advantage of being viable for use in paraffin-embedded immunohistochemistry assays, following microwave-mediated antigen retrieval. This situation has improved, and today around half the Ki67 antibodies we at Novus Biologicals have in our antibody catalog can be used for paraffin embedded sections. However, these products are exclusively for research use only, and MIB1 antibodies remain the norm in the clinical environment.

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The Osteopontin Antibody and Hepatic Research

Monday, May 23rd, 2011

Antibody suppliers, such as us at Novus Biologicals, supply a wide range of cell marker products, among them the osteopontin antibody. Recently, the osteopontin antibody has proven useful in hepatic cancer research.

Osteopontin (OPN) is mainly expressed by the osteoblasts; its primary function is in the mineralization of bone. However, OPN is expressed to a lower degree in other areas of the body, being involved in cell adhesion, cell migration and the inflammatory response.

Osteopontin has been implicated in a number of inflammatory diseases including rheumatoid arthritis (RA), multiple sclerosis and hepatitis. It is also upregulated in a number of cancers. Osteopontin antibody studies have shown OPN is modified in a number of tissue-specific ways, including phosphorylation, glycosylation, sulphation and transglutamination.

OPN is known to have two central domains with multiple integrin binding sites, which are activated following thrombin-induced cleavage. Cleavage can also be initiated by MMP proteins at central and C-terminal sites, although C-terminal binding seems to have no integrin effect. Importantly, OPN can undergo complete digestion by MMP-9, resulting in the release of a 5 kDa fragment. In 2007, Takafuji et al published a study showing this fragment to play a role in the development of hepatocellular carcinomas, promoting CD44-mediated metastasis.

Administration of neutralizing murine osteopontin antibody has proven successful in treating RA and fulminant hepatitis in mice, but is of little clinical use in humans. Recently, B. Zhang et al succeeded in ‘humanising’ a murine osteopontin antibody, while retaining full binding affinity. The study strongly suggested humanized anti-osteopontin antibody may have a therapeutic use in humans, though it must be stressed the products sold by antibody suppliers are for research use only.

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Actin Nucleators and Other Developments in Actin Antibody Research

Friday, May 13th, 2011

A highly conserved, abundant protein found in practically all eukaryotic cells, actin is a monomeric subunit of skeletal muscle thin filaments, and cytoskeleton microfilaments. Actin antibody products are routinely used in cell marker and loading control assays. However, actin antibody reagents are also used for cytoskeleton, cell motility, cytokinesis and cell signalling research. Our antibody catalog covers all the actin isoforms, with an extensive range of alpha, beta and gamma actin antibody products.

Actin antibody studies have revealed polymerization and depolymerization of actin to be essential to chemotaxis (cell motility) and cytokinesis (cell division). Polymerization is dependent upon nucleating factors such as ARP and the formin protein family. The Arp1/2 complex has been widely studied by actin antibody researchers. The Arp1 and 2 proteins mimic the structure of monomeric actin, forming a complex which serves as a nucleation site for new microfilaments. The formins are, like actin, highly conserved proteins involved in actin remodelling, cellular morphology and coordination of microtubule and actin dynamics.

Recent actin antibody research has identified several cellular factors which modulate formin expression to affect actin nucleation and elongation. Formins with cellular functions apart from actin polymerization have also been discovered. Recent additions to the formin nucleator database include Cordon-Bleu, Cappuccino, Leiomodin and Spire. In addition, several proteins have been identified which stimulate ARP2/3 activity to affect actin nucleation and dynamics. These include WASH (the WASP and SCAR homologue); WHAMM (WASP homologue associated with actin, membranes and microtubules) and the junction-mediating regulatory protein JMY.

Actin antibody research continues to uncover new genetic facts about actin polymerization and the cytoskeleton. We at Novus Biologicals have an extensive antibody catalogue covering this area of research.

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The Akt Antibody and its Role in Cancer Research

Monday, May 9th, 2011

There are three human isoforms of the AKT gene, which plays a key role in several signalling pathways. Akt antibody studies have shown the Atk kinases to play a diverse number of roles within the cell, regulating angiogenesis, apoptosis, protein synthesis, intermediary metabolism and cellular differentiation. We at Novus Biologicals have a wide range of Akt products on our antibody database, targeting all three isoforms.

Akt antibody research has identified specific roles for the three isoforms of Akt. Akt2 plays an important role in insulin signalling, while Akt3 is thought to be involved with neuronal development. Akt1, the founding member of the family, is of major importance to cancer researchers. A key player in the PI3K/AKT/mTOR and several other pathways, Akt1 signalling promotes hypertrophy (growth) of skeletal muscle and other tissues, and promotes cell survival by inhibiting apoptotic processes.

Akt1 was originally identified as an oncogene in the AKT8 transforming retrovirus, and has since been shown to be critical to the growth and progression of a number of human neoplasms. It also plays an indirect role, acting on oncogenic signals resulting from mutations in tumour-suppressor genes and other oncogenes.

Today, the entire Akt antibody database is used in cancer research. Overexpression of Akt2 and Akt3 has been directly linked to the development of epithelial neoplasms, breast tumours, prostate cancer, ovarian cancer and skin cell melanomas. Researchers at the MORI Institute, Tufts University, are using insertional mutagenesis and other genetic techniques to probe the function of all three isoforms. Other groups are using Akt antibody products to develop antineoplastic drugs.

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The c-Myc Antibody – A Major Tool in Cancer Research

Friday, April 22nd, 2011

C-Myc is a widely expressed transcription factor, regulating cellular differentiation, proliferation, cell cycle progression and pro-apoptotic gene expression. The c-Myc antibody is widely used in cancer research, as a number of human tumors have been attributed to altered c-Myc expression.

In normal tissue c-Myc expression is tightly regulated, only occurring when cells actively divide. However, in cancer cells genetic aberrations cause the gene to be expressed in an uncontrolled fashion. C-Myc antibody studies have revealed abnormal expression of the protein in 90% of gynecological cancers and 80% of breast tumors. Overexpression has also been reported in 70% of colon cancers and 50% of hepatic carcinomas, as well as a number of hematological cancers. Around 100,000 cancer deaths a year can be attributed to the c-Myc gene in the US alone.

C-Myc is a basic helix-loop-helix-leucine zipper (b-HLH-LZ) protein. It can be activated by forming a heterodimer with Max, another b-HLH-LZ monomeric protein. It is thought transcription occurs through a combination of histone acetylation and direct interaction with the transcription apparatus. Max has been known to bind to certain Mad proteins, forming heterodimers which block c-Myc transcriptional activity in association with other proteins, including histone deacetylases and Sin3.

C-Myc antibody research has revealed cellular proliferation and cell cycle progression may be controlled by phosphorylation at Thr58/Ser62, via glycogen synthase kinase 3, cyclin dependent kinase, ERK2 and JNK (C-Jun N terminal Kinase) interaction. Among the c-Myc antibody products in our antibody catalog, we at Novus Biologicals have a phospho c-Myc antibody specific to Thr58/Ser62 phosphorylated c-Myc. It does not react with the protein in its non-phosphorylated form.

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The CD4 Antibody – More than Just a Useful Cellular Marker

Friday, April 8th, 2011

CD4 is a member of the cluster of differentiation family of proteins, mainly expressed on the surface of thymocytes and a specific subset of mature T-cells. CD4 antibody studies have also shown it expressed on monocytes, cortical cells, microglial cells, dendritic cells and macrophages. The CD4 antibody is widely used in cell marker studies, CD4 being one of the most common CD markers in use. However, the CD4 products in our antibody catalog have also proven useful in cell biology, immunology and cytokine research.

CD4 is a co-receptor for the TCR (T Cell Receptor) heterodimer. It has both intracellular and extracellular domains. The intracellular domain amplifies TCR signalling by activating the tyrosine kinase LCK enzyme, essential to the activated T cell signaling cascade. The four extracellular domains interact directly with MHC class II molecules, which are released by antigen-presenting cells. The main function of CD4 is to increase interaction between the TCR and antigen-class II MHC complex.

CD4 antibody studies have shown CD4, together with CD3 chains and the CD8 co-receptor, aids signal transduction through the TCR. The CD4 antibody is useful in distinguishing T-helper from T-cytotoxic cells, both of which express the TCR, as CD4 is specific to T-helper cells while CD8 is expressed on T-cytotoxic cells.

The CD4 antibody is central to HIV research, as the viral envelope protein achieves entry into the host cell by CD4 binding, lowering CD4 levels. The CD4 antibody is routinely used in the CD count test, used to monitor CD levels in HIV positive patients.

We at Novus Biologicals have a wide range of CD4 antibody products in our antibody catalog.

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The Beta-actin Antibody as a Loading Control

Monday, March 28th, 2011

One of six actin isoforms so far identified, beta-actin is a highly conserved cytoskeletal protein involved in cell structure, motility, and cohesion. We at Novus Biologicals have 35 beta-actin antibody products in our antibody catalog, used in areas such as cytoskeleton and signal transduction research. They are also used as loading controls in protein assays.

Beta-actin is known as a “housekeeping” protein, i.e. it is expressed constantly, and at high levels, in all the cell types used in protein research. It is therefore a useful loading control in, for example, Western blot analysis. Loading controls serve a number of purposes; they ensure the protein of interest has been correctly loaded on the gel, that it is being transferred correctly, and that all reagents are functioning normally. So long as the molecular weight of the test protein is sufficiently different to that of the beta-actin antibody, distinct bands will be achieved.

In 2010, D. Grunwald and R.H. Singer used the beta-actin antibody to demonstrate a new fluorescence microscopy technique for in vivo imaging of mRNA during nuclear pore transport, using labelled beta-actin mRNA. The nuclear pore is the only link between the nucleus and cytoplasm, and of great interest to molecular biologists. However, it is only around 120nM in diameter, making in vivo light microscopy studies impossible. By utilising fluorescence microscopy, it was possible to spatially measure the three stages of mRNA transport (docking, transport and release) with nanometre precision. The quality and purity of the products in our antibody catalog makes them ideal for studies of this kind.

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ABCA1 Expression Down-regulated by SREBP microRNA

Friday, March 18th, 2011

The ABCA1 (ATP-binding cassette transporter-A1) gene encodes a transmembrane protein, which plays a major role in phospholipid homeostasis by regulating cholesterol efflux from the cell. ABCA1 antibody studies have shown ABCA1 expression is up/down regulated by the transcription factors LXR and SREBP2 respectively. Now, new evidence points to microRNA (mRNA) being integral to SREBP2 down-regulation of ABCA1. We at Novus Biologicals have a large number of LXR, SREBP2 and ABCA1 antibody products in our antibody catalogue.

ABCA1 is expressed on the Golgi body and plasma membrane. Expression is regulated by transcription factors in response to alterations in the cholesterol flux. Its role is to mediate transport of lipids between the two expression sites, and to moderate cholesterol and phospholipid efflux to the apo-A1 and apoE apolipoproteins, for HDL (high-density lipoprotein) formation. The protein is expressed in high levels in the liver, gut and adipose tissue.

SREBP-2 (sterol-regulatory-element-binding protein 2) controls cholesterol homeostasis by upregulation of genes involved in cholesterol synthesis and uptake, e.g. HMG-CoA, while LXR upregulates expression of ABCA1 and other cholesterol efflux genes. Oxysterols (cholesterol derivatives) inhibit SREBP2 activation whilst acting as LXR ligands. ABCA1 antibody studies conducted by J.Wang have suggested SREBP2 controls ABCA1 expression by maintaining a supply of oxysterol ligands for LXR.

Recently, miRNAs have been shown to play an important role in cholesterol homeostasis by post-transcriptional regulation of a number of lipid metabolism genes, with ABCA1 antibody studies demonstrating ABCA1 inhibition by miRNA action. A study conducted in 2010 showed inhibition was achieved by two miRNAs embedded in the SREBP2 host gene. This exciting development has opened new avenues of research for our antibody catalog.

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Are ABCA1 Mutations a Risk Factor for Strokes?

Monday, February 21st, 2011

The ATP Binding Cassette Transporter (ABCA1) gene encodes the cholesterol regulatory efflux protein, which plays a key role in lipid metabolism. ABCA1 antibody products are an important part of any antibody catalog covering atherosclerosis disease research.

Atherosclerosis (narrowing of the arteries) is characterized by a build-up of fatty plaques, containing cholesterol, causing arteries to narrow. These plaques can then become ulcerated, causing blood clots to form. If this occurs in the carotid arteries the clots can travel to the brain, causing a stroke. In the general population, low plasma HDLC levels are well documented to increase the risk of coronary heart disease.

ABCA1 antibody studies in animal models have shown ABCA1 gene mutations increase the risk of atherosclerosis. Researchers also discovered that oxidation of LDL in the cells of the arterial wall is modulated by ABCA1. In atherosclerotic plaques, ABCA1 upregulation occurred, suggesting a link between ABCA1 expression and the formation of plaques. Results also suggested ABCA1 polymorphisms can affect lipid profiles, and that ABCA1 may play an essential role in regulating ApoA-I and ApoE levels in the brain.

In humans, a 2005 Hungarian study of stroke patients suggested two ABCA1 polymorphisms which may offer protection from strokes. However, a similar study by Pasdar et al in 2007 showed no significant effect – positive or negative – in four ABCA1polymorphisms, although they reported a change in serum lipid levels.

In 2009, P. Isoviita et al conducted CD36 and ABCA1 antibody assay studies on carotid plaques (CPs). The results suggested that an imbalance between lipid efflux and influx, represented by CD36 and ABCA1 levels, could lead to carotid plaque build-up, intraplaque hemorrhages and increased stroke risk. We at Novus Biologicals have an extensive antibody catalogue covering ABCA1 antibody research.

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