Antibody News

CD98 - cell surface glycoprotein that promotes cell adhesion, growth, and survival

Friday, July 31, 2015 - 13:24

CD98 is a heterodimeric glycoprotein that contains an 80 kDa heavy chain and a 40 kDa light chain. The CD98 heavy chain is also known as the 4F2 antigen heavy chain or FRP-1, and it is encoded by the SLC3A2 gene. The CD98 heavy chain is capable of binding to β-integrins to mediate cell adhesion, motility, growth, and survival (1). Meanwhile, the CD98 light chain allows amino acid transport. Different isoforms of the light chain allow expression of six different L-amino acid transporters. The CD98 heavy chain can be expressed independently; however, expression of the CD98 light chain is dependent on the presence of the heavy chain. CD98 was first identified for its role in lymphocyte activation and the adaptive immune response (2). In adaptive immunity, antigens are presented to a pool of lymphocytes until its complementary match is identified. Upon matching, clonal expansion of the lymphocyte is crucial for combating the infection and...

Akt1 - a central player in cell survival signaling

Thursday, July 30, 2015 - 13:17

Akt1 is one of three isoforms of Akt belonging to the AGC family of serine/threonine kinases (Akt1, Akt2, and Akt3). All Akt isoforms contain an N-terminal Plekstrin Homology (PH) domain, a C-terminal regulatory domain, and a central catalytic kinase domain (1). Akt is a major downstream target of the PI3-K signaling pathway. The Akt1 isoform is fully activated by phosphorylation at three sites- T308, T450, and S473. Akt1 resides in an inactive state due to intramolecular interactions between the PH domain and the kinase domain. PI3-K signaling induces a conformational change that exposes the active sites to allow phosphorylation and activation of Akt1 (1). Akt plays a variety of roles in normal cellular metabolism, growth, proliferation, and survival. It has also been implicated in malignancies as a driver of angiogenesis, migration, and invasion. Recent studies have begun to tease apart the signaling specificity of the three Akt isoforms. Akt1 is expressed in many...

Caspase-4 - a human protease with roles in inflammation and immunity

Wednesday, July 29, 2015 - 15:28

Caspases are a family of cysteine-aspartic acid proteases that cleave caspase proenzymes as well as other protein substrates. Caspases are well known for their role in apoptosis, but they also play a significant role in other cellular processes including inflammation (1). Apoptotic caspases include Caspases-3, -6, -7, -8, and -9. Meanwhile, human inflammatory caspases include Caspases-1, -4, -5, and -12. The role of Caspase-4 and -5 have been particularly difficult to study given that mice only express inflammatory Caspases-1,-11, and -12. Recent data suggests that human caspases-4 and -5 are orthologs of the murine Caspase-11 (1). Full length Caspase-4 is a 45 kDa protein while the cleaved isoform is only...

TSC2 - GTPase activating protein involved in cell cycle inhibition

Monday, July 27, 2015 - 14:59

TSC2 is a tumor suppressor gene that encodes a 200 kDa protein called tuberin. TSC2 heterodimerizes with TSC1 to form a complex with GTPase-activating protein (GAP) activity. The C-terminus of TSC2 contains the GAP domain responsible for this catalytic activity. The complex was first discovered through its role in the tumor-forming condition Tuberous Sclerosis. Mutations in TSC1 and TSC2 can either destabilize the complex or compromise the GAP activity. The TSC1-TSC2 complex acts as a GAP for the small G-protein Rheb, expressed ubiquitously throughout the body (1). Rheb inhibits mTOR signaling to downregulate protein synthesis and cell growth. Thus in the absence of TSC1-TSC2, mTOR signaling allows unchecked cellular growth and proliferation. TSC1-TSC2 acts as a nutrient sensor for amino acids, growth factors, hormones, etc. and mediates cell cycle progression. The TSC1-TSC2 complex can be phosphorylated at a number of sites that are either activating or inactivating....

ATG4B - a cysteine protease involved in autophagosome elongation

Friday, July 24, 2015 - 11:29

Autophagy can be broken down into 4 main stages: phagophore nucleation, autophagosome elongation, autophagosome docking and fusion with a lysosome, and vesicle breakdown and degradation. ATG4B is one of four ATG4 homologs (ATG4A, ATG4B, ATG4C, and ATG4D) involved in autophagosome elongation. ATG4B encodes a 48 kDa protein called autophagin-1 that is a member of the C54 family of cysteine proteases. ATG4B exists in an autoinhibited state where two of its structural domains hide its catalytic cysteine (1). ATG4B binding to its substrate induces a conformational change that exposes the active site and allows cleavage of the substrate. ATG4B is the least specific of the ATG4 family and is capable of recognizing multiple homologs of its substrate ATG8 (2).

ATG8 is an ubiquitin-like protein involved in...

TSC1 - a negative regulator of mTOR signaling

Thursday, July 23, 2015 - 14:57

TSC1 is a tumor suppressor gene that encodes a 130 kDa protein called hamartin. TSC1 was first identified as an oncogenic driver of Tuberous Sclerosis, a condition characterized by numerous benign tumors of the skin, brain, heart, and lungs. A mutation in TSC1 is responsible for the uncontrolled growth characteristic of these tumors. This discovery led to a greater understanding of the physiologic role of TSC1 as a negative cell cycle regulator. The distinct but related gene TSC2 encodes a 200 kDa protein called tuberin. TSC1 and TSC2 heterodimerize to form a complex that acts as a GTPase-activating protein (GAP) for the G-protein Rheb (1). Rheb is a member of the Ras family that inhibits mTORC1 signaling when activated by the TSC1-TSC2 complex. mTORC1 signaling promotes cell growth and proliferation and aberrant signaling promotes tumor formation. The TSC1-TSC2 complex acts as a sensor for levels of growth factors, amino acids, and other...

ATG16L1 - a key player in the development of the autophagosome

Wednesday, July 22, 2015 - 13:37
Untitled Document

Like apoptosis, autophagy is a highly regulated physiologic process that involves cellular degradation and recycling of organelles and macromolecules. Autophagy is a survival mechanism induced by states of stress, starvation, and infection. A double membraned autophagosome sequesters the desired cellular components before fusing with a lysosome to form an autolysosome destined for degradation. LC3 lipidation and recruitment to the autophagosome is crucial to its maturation and eventual fusion with a lysosome. ATG16L1 (autophagy-related protein 16-1) forms a highly conserved complex with ATG5 and ATG12 to direct LC3 to the autophagosome (1). ATG16L1 is a 68 kDa protein that exists in the cytoplasm and is directed to the preautophagosomal structure (PAS) as needed. ...

OATP8 - A membrane transport protein responsible for cancer drug uptake

Monday, July 20, 2015 - 14:21

Human hepatocytes express important transport proteins that are responsible for the uptake and removal of organic anions from the blood. These proteins are members of the organic anion-transporting polypeptide (OATP) family and are essential for proper liver function. OATPs are encoded by the SLC21 gene family and contain 12 transmembrane alpha-helices and are primarily expressed in the liver. The OATP family transports endogenous substrates like bile salts and steroid hormones as well as exogenous molecules like anticancer drugs and imaging agents. This broad specificity makes OATPs an important research topic for understanding basic liver biology and for designing therapeutic and diagnostic strategies. Of particular importance is OATP8. Early studies of OATP8 used immunofluorescent staining with OATP8 antibodies to demonstrate basolateral localization in human hepatocytes (1). Additionally immunoblotting with...

Thrombomodulin - A multifunctional protein with roles in inflammation and coagulation

Friday, July 17, 2015 - 14:40

Thrombomodulin, also known as BDCA-3, is a glycosylated transmembrane protein present on the surface of vascular endothelial cells. Thrombomodulin is a high-affinity receptor for thrombin, a key protein in the coagulation cascade. Formation of the thrombomodulin-thrombin complex blocks the thrombin dependent conversion of fibrinogen to fibrin and also catalyzes the activation of protein C. Active protein C is able to proteolytically inactivate enhancers of the coagulation cascade. Thrombomodulin’s dual ability to directly block thrombin function and to activate a negative regulator of coagulation makes it essential component of the anticoagulation system. Thrombomodulin is known for its role in anticoagulation but has recently been shown to have important functions in inflammation as well. The extracellular N-terminus of thrombomodulin consists of two domains; a lectin-like domain and an EGF-repeat domain. The EGF-repeat domain is responsible for thrombin binding...

5 Simple Western Antibody Facts

Thursday, July 16, 2015 - 12:46

Novus Biologicals has 800+ antibodies and 650 unique targets validated on the Simple Western platform. All are certified in-house by our experienced scientists. They are backed by 175+ peer reviews and more than 5,600 citations in a variety of applications. Learn more about Simple Western in the Infographic below and check out our list of certified antibodies

simple western

Beclin 2, a mammal-specific homolog of Beclin 1 with unique functional similarities and differences

Wednesday, July 15, 2015 - 15:57
Beclin 2 (BECN2) is also called Beclin-1-like protein 1/ BECN1P1 and it was recently identified by He et al 2013 as a mammal-specific homolog of the evolutionarily conserved protein Beclin 1 which is well established for its role in the regulation of autophagy and oncogenic suppression (1). He et al 2013 documented that human Beclin 2 is 57% similar to Beclin 1, and they confirmed its presence in several tissues including brain, placenta, thymus, uterus and skeletal muscles. Further studies from various labs established Beclin-2’s critical role in two distinct lysosomal degradation pathways: as a regulator of autophagy and as a regulator of G-protein coupled receptors/GPCRs turnover. Like Beclin 1, Beclin 2 was also found to regulate autophagy and its effects were demonstrated in basal or starvation-induced autophagy experiments involving bafilomycin A1 and cultured mammalian cells wherein it...

c-Myc - transcription factor and oncogene

Monday, July 13, 2015 - 14:44

c-Myc is a protein of the Myc family of transcription factors (c-Myc, B-Myc, L-Myc, N-Myc, and s-Myc) encoded by the MYC proto-oncogene. c-Myc was first discovered as the cellular homolog of the retroviral v-Myc oncogene. c-Myc is a transcription factor for genes involved in cell growth, proliferation, differentiation, and apoptosis. c-Myc contains a basic helix-loop-helix domain and a leucine zipper domain that allow for its heterodimerization with its binding partner Max. Myc/Max complexes are able to activate genes via the Myc transactivation domain (1). In healthy cells, c-Myc expression is tightly regulated by NFκB and other transcription control mechanisms. However, c-Myc translocations have been identified in numerous malignancies that allow deregulation and constitutive expression of c-Myc. c-Myc translocations account for almost 100% of Burkitt ’s lymphoma cases (2).  Translocations and mutations in c-Myc account for up to one seventh of all U.S. cancer...

Caspase-8 - a pro-apoptotic protein with dynamic roles in normal physiology and pathology

Thursday, July 9, 2015 - 14:37

Caspases are a family of cysteine-aspartic acid proteases that are responsible for the initiation and execution of apoptosis. Caspase-8 is a 55 kDa protein expressed as an inactive procaspase that resides in the cytosol. Activation of Caspase-8 requires cleavage into its large (17-21 kDa) and small (10-13 kDa) catalytic subunits. Caspase-8 has been shown to play a role in the induction of apoptosis by both death receptor mediated and non-receptor mediated mechanisms (1). Caspase-8 signals to effector Caspase-3 to execute apoptosis. Caspase-8 expression and activation is regulated on many levels. The prodomain of Procaspase-8 plays an important role in Caspase-8 activation. The prodomain interacts with FADD (Fas-Associated protein with Death Domain) to initiate apoptosis via the Fas/FasL pathway. The protein FLIP inhibits Caspase-8 activation by binding to FADD and preventing Procaspase-8 cleavage (1). Meanwhile, proteins of the inhibitors of apoptosis family (Survivin,...

Novus has teamed up with R&D Systems to make great antibodies even better

Tuesday, July 7, 2015 - 13:04

R&D Systems' primary antibodies are made in house at our facility in Minneapolis, MN with the goal of creating the most specific and replicable lots of antibody available. From careful antigen design to in-house testing in multiple applications, the aim of R&D Systems is to maximize the specificity of each antibody and eliminate off target binding.  Going further, R&D Systems’ antibodies are repeatedly tested to ensure the industry’s best lot to lot reproducibility for a product you can count on in all of your experiments now, and later on in your project.

Flow cytometry requires primary antibodies conjugated to multiple fluorophores to allow multiplexing several targets to identify and characterize specific cell populations of interest.  Additionally, flow cytometry requires highly specific reagents that researchers can rely on because it is difficult to completely control for non-specific binding.  To address these...

Survivin - an inhibitor of apoptosis that drives tumorigenesis and metastasis

Monday, July 6, 2015 - 14:30
Untitled Document

Apoptosis is the tightly regulated process of programmed cell death. It plays an important role in normal physiologic development but has also been implicated in a number of diseases. Apoptosis is constantly downregulated by a family of anti-apoptotic proteins known as the inhibitors of apoptosis proteins (IAP). Every member of the IAP family contains one to three copies of a baculovirus IAP repeat (BIR domain). The BIR domain is a zinc-binding motif that allows these proteins to interact with and inhibit the pro-apoptotic caspases. One of the more recently characterized members of this family is Survivin, a 16.5 kDa protein, the smallest in the family. Survivin is unique in that it contains only one BIR domain and homodimerizes with itself before interacting with a caspase. Survivin plays a critical role in fetal development but is undetectable in healthy adult tissues...

SREBP2 - regulating cholesterol homeostasis and lipid metabolism

Wednesday, July 1, 2015 - 14:47

Sterol regulatory element-binding proteins (SREBP) are important transcription factors regulating the synthesis and uptake of lipids including cholesterol. This essential role in lipid metabolism makes investigations into the functions SREBPs important for understanding metabolic disorders such as diabetes and may provide insight for future drug treatment strategies. SREBPs are basic helix-loop-helix (bHLH) leucine zipper transcription factors that bind to sterol response elements (SRE) to enhance the expression of target genes including LDL receptor and lipid synthesis genes. In humans there are two SREBP genes, SREBP1 and SREBP2. SREBP1 is expressed primarily in the liver while SREBP2 is ubiquitously expressed. SREBPs are synthesized as ER membrane proteins where they bind with SREBP cleavage-activating protein (SCAP), an important cholesterol sensor and transporter. This association with SCAP retains SREBP in...

MMP3 - a potential target for arthritis therapies

Monday, June 29, 2015 - 14:04

Matrix metalloproteinases (MMPs) are responsible for the degradation of extracellular matrix proteins. MMPs are essential for tissue remodeling during normal processes such as embryonic development as well as pathological conditions such as arthritis and tumor metastasis. MMP3, a member of the stromelysin family, has broad specificity for proteins such as collagens, fibronectin, proteoglycans, and elastin making it an important player in extracellular matrix remodeling. These activities are especially important during tumorigenesis by enhancing epithelial to mesenchymal transition. MMPs are generally secreted as a proform and subsequently processed and cleaved into the active form. However under oxidative stress and during apoptotic signaling MMP3 can also be found in its active form inside of cells and may have important implications in neurodegenerative diseases like Alzheimer disease and Parkinson disease (1). A number of specific MMP inhibitors are currently in...

FGFR1 - regulating cell growth and proliferation in development and disease

Friday, June 26, 2015 - 13:15

The vertebrate fibroblast growth factor receptor (FGFR) family is an important group of proteins involved in embryonic development and the growth and proliferation of adult cells. Mutations in FGFR proteins can lead to pathologies including bone or limb defects and various forms of cancer. FGFR proteins are receptor tyrosine kinases that, upon ligand binding, dimerize and signal through the MAPK and PLCγ pathways. FGFR1 is a well characterized member of this protein family consisting of an extracellular region, a single-pass transmembrane domain, and the intracellular tyrosine kinase domain. The extracellular region contains a heparin binding domain responsible for interaction with the extracellular matrix while the intracellular domain interacts with downstream effectors after receptor dimerization to propagate signals (1). FGFR1 exists in many alternatively spliced isoforms including a soluble, secreted isoform lacking the transmembrane and kinase domains. While...

Calnexin - an ER chaperone that folds the cell's glycoproteins

Thursday, June 18, 2015 - 14:49

Calnexin is an abundant 90kDa chaperone protein that resides in the membrane of the endoplasmic reticulum. Calnexin and the related calreticulin protein function together to ensure the proper folding of glycoproteins. By binding to partially folded or misfolded proteins, Calnexin functions as an important quality control monitor ensuring proper folding of proteins destined for the plasma membrane or secretion. Calnexin contains a lectin site that recognizes substrate proteins through a transient and intermediate oligosaccharide containing a terminal glucose residue. Through this interaction calnexin binds to and participates in the folding of most if not all glycoproteins. Calnexin also contains binding sites for it cofactors ATP and Ca2+  and is able to recruit enzymes that catalyze disulfide bond formation and isomeriztion to aid in folding. Calnexin binding retains substrate proteins in the ER until they are fully mature and their...

GPR78 - an orphan receptor involved in psychiatric illness

Monday, June 15, 2015 - 15:06

G-protein coupled receptor 78 (GPR78) was identified based on homology to other GPCR family members. The GPR78 gene encodes an orphan receptor protein that is 363 amino acids in length and contains the typical seven transmembrane domain found in GPCRs. The protein is widely expressed in the mammalian brain including the pituitary and is also found in the placenta. While a ligand for GPR78 has yet to be identified, its expression pattern suggests a potential role in hormone and stress regulation as well as during pregnancy. Future research with GPR78 antibodies may assist in assays to identify the endogenous and pharmaceutical ligands for this orphan receptor. A study of GPR78 in a tissue culture system demonstrated constitutive activity as well as elevated cAMP levels providing preliminary evidence of GPR78’s function in signal transduction (1). Further investigation using GPR78 antibodies...

Integrin alpha v beta 3 - a target for inhibiting tumor angiogenesis

Friday, June 12, 2015 - 14:37

Integrins are a family of transmembrane proteins involved in diverse processes including cell adhesion, signal transduction, cell migration, and differentiation. They exist as heterodimers consisting of noncovalently linked alpha and beta subunits. Integrin complexes span the plasma membrane and link the cytoskeleton with the extracellular matrix. In mammals there are 18 alpha and 8 beta subunits that can assemble into 24 distinct integrin heterodimers with alternative splicing adding even more diversity. In addition to binding the extracellular matrix, integrins also bind to endogenous ligands including soluble proteins and cell surface proteins. Integrin alpha v beta 3 (Integrin αvβ3), also known as the vitronectin receptor, has important roles in angiogenesis and tumor metastasis and binds to a wide range of extracellular matrix proteins containing the RGD-motif. Integrin alpha v beta 3 is highly expressed in cells of the bone, placenta, and invasive tumors where it...

LAMP2 - a marker of lysosomes and late endosomes

Thursday, June 11, 2015 - 14:42

Lysosomes are membrane-bound organelles responsible for the degradation of various biological macromolecules. Vesicles containing hydrolytic enzymes bud from the Golgi and fuse with endosomes to form the mature lysosome capable of breaking down various types of cargo. Their general function in recycling biological molecules places lysosomes at center of various processes including autophagy, endyocytosis, and phagocytosis. These functions are essential for maintaining cellular homeostasis through, for example, autophagy of damaged organelles or the endocytosis and degradation of activated signaling receptor complexes. Lysosomal-associated membrane protein-2 (LAMP-2) is ubiquitously expressed and is an abundant component of the lysosomal membrane. LAMP-2 contains a large luminal domain that is heavily glycosylated followed by a single transmembrane domain and a small cytoplasmic facing carboxyl terminus. LAMP-2 acts as a receptor for the degradation of specific...

TGF-beta 1 - a versatile signaling molecule with roles in development and disease

Wednesday, June 10, 2015 - 14:52

The transforming growth factor-β (TGF-beta) family consists of a wide variety of signaling proteins with roles in development. TGF-beta signaling controls growth, differentiation, and immune responses and is often misregulated in cancer. TGF-beta 1 is the most widely expressed and abundant isoform of the TGF-beta family. TGF-beta proteins signal through two classes of receptors: type I (TβRI) and type II (TβRI). These receptor proteins are serine threonine kinases found at the cell surface. Binding of TGF-beta induces the formation of a heterocomplex with TβRI and TβRII and leads to the phosphorylation of TβRI by TβRII. The active phosphorylated form of TβRI recruits and phosphorylates downstream effector SMAD proteins, which can then translocate to the nucleus where they can regulate transcription. Non-canonical signaling by TGF-beta 1 can also be mediated through various pathways including MAPKs, small GTPases, and PI3Ks. TGF-beta proteins are synthesized as pro-...

PINK1 - performing mitochondrial quality control and protecting against Parkinson’s disease

Monday, June 8, 2015 - 15:39

PTEN-induced putative kinase 1 (PINK1) is a serine/threonine kinase with important functions in mitochondrial quality control. Together with the Parkin protein, PINK1 is able to regulate the selective degradation of damaged mitochondria through autophagy. Normally PINK1 is imported into the mitochondria where it is targeted for proteolytic cleavage. This cleavage event results in unstable products and is the reason PINK1 is difficult to detect in healthy mitochondria. In damaged mitochondria loss of the membrane potential prevents the import of PINK1 and causes it to reside in the outer mitochondrial membrane. Exposed PINK1 in the outer membrane then recruits Parkin which acts as an E3 ligase to ubiquitinate mitochondrial proteins. This leads to mitochondrial degradation through either proteasome or autophagy pathways and can protect cells from oxidative stress induced apoptosis.  PINK1 may also regulate mitochondrial fission/fusion events....

NOXA - a BH3-only protein balancing cell death decisions

Friday, June 5, 2015 - 15:30

Noxa is a BH3-only protein involved in regulating cell death decisions. Noxa is a primary p53-response gene and is upregulated in response to p53 overexpression or DNA damage. Noxa can also be induced by alternative mechanisms including through a hypoxia-response element found in its promoter. Noxa localizes to mitochondria where it binds to Mcl1, an anti-apoptotic Bcl2 family member. Binding of Mcl1 by Noxa not only neutralizes its pro-survival effects but can also lead to proteasomal degradation of Mcl1 to further enhance apoptosis. While Noxa is important for induction of cell death in some cellular contexts, overexpression of Noxa does not always lead to a strong apoptotic response. This suggests Noxa-induced cell death may depend on the levels of other Bcl2-like and BH3-only proteins within the cell. While the relevance of Noxa in tumor suppression is unclear insight into the regulation of...

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