Antibody News

CD163 - a scavenger receptor with important roles in inflammation

Friday, May 29, 2015 - 14:46

Scavenger receptors play important roles in homeostasis and innate immunity by binding to endogenous and foreign molecules. Scavenger receptors on the plasma membrane of macrophages bind to ligand and allow their internalization and can also mediate pro- or anti-inflammatory signaling. The plasma membrane glycoprotein CD163 is a member of the scavenger receptor cysteine-rich (SRCR) protein family. CD163 contains nine SRCR domains and is expressed in macrophages and monocytes where it plays a role in innate immunity and regulation of inflammation in response to ligand binding. CD163 binds specifically to hemoglobin (Hb)-haptoglobin (Hp) complexes produced during hemolysis to allow their internalization and lysosomal degradation. Additionally, CD163 has been shown to bind other ligands including some bacterial or viral pathogens. Recognition of these ligands leads to internalization and breakdown as well as...

ATG7 - an E1 enzyme for the ubiquitin-like autophagy proteins

Friday, May 15, 2015 - 09:47

Autophagy is an essential cellular process that maintains homeostasis through the degradation and recycling of cytoplasmic organelles and macromolecules. Substrates targeted for autophagy are engulfed in a double-membrane structure called the autophagosome which is then targeted to the lysosome for degradation. The initiation of autophagy requires two separate ubiquitin-like protein (UBL) systems that regulate autophagosome assembly. In these systems Atg7 acts as an E1-like enzyme for the UBLs Atg12 and Atg8. Atg7 binds to and activates these UBLs to allow their transfer to an E2 enzyme and eventually their targets. Upon initiation of autophagosome assembly Atg7 binds to the UBL Atg12 and transfers it to its final binding partner Atg5 via the E2 enzyme Atg10. The Atg12-Atg5 conjugate assembles into a large multimeric complex along with Atg16....

p62/SQSTM1 - targeting ubiquitinated proteins for autophagic degradation

Friday, May 15, 2015 - 08:29

During autophagy ubiquitinated cargo or substrates are engulfed in a double-membrane autophagosome and transported to the lysosome for degradation. This process is important for maintaining cellular homeostasis and for degrading damaged organelles or misfolded protein aggregates. p62, also known as sequestosome 1 (SQSTM1), is an autophagy receptor that recognizes and recruits cargo to the autophagosome through its interaction with Atg8. Atg8, known as LC3 in mammals, is a ubiquitin-like protein that is conjugated to the lipid phosphatidylethanolamine which anchors it into the double-membrane phagopore structure. Atg8/LC3 is essential for binding to and recruiting the core autophagy machinery through an Atg8 interacting motif (AIM) or through the LC3-Interacting region (LIR). AIM/LIR containing autophagy receptors, including p62/SQSTM1, recognize ubiquitinated proteins and target them to the autophagosome for destruction. Autophagy is...

Hsc70 - a chaperone protein with diverse cellular functions

Friday, May 15, 2015 - 08:21

Heat shock cognate 71 kDa protein (Hsc70), also known as HSPA8, is a member of the heat shock protein 70 family (Hsp70). Unlike Hsp70, it is a constitutively expressed chaperone protein and is involved in diverse cellular processes including protein folding and protein degradation. Hsc70 consists of two domains: the nucleotide binding domain (NBD) and the substrate binding domain (SBD). Hsc70, with the help of accessory proteins, exerts its chaperone activity by binding to short hydrophobic stretches of nascent or unfolded polypeptides through the SBD in an ATP-dependent manner. ATP hydrolysis then triggers a conformational change to induce protein folding and the release of the substrate. Nucleotide exchange factors then facilitate the exchange of ADP for ATP allowing Hsc70 to bind to a new substrate and repeat the cycle. The ATPase activity of Hsc70 is also important for endocytosis during the uncoating of clathrin-coated vesicles. In conjunction with cochaperones...

HLA G - mediating immune tolerance during pregnancy

Friday, May 15, 2015 - 08:11

Human leukocyte antigen G (HLA G) is a major histocompatibility complex (MHC) class I molecule that is primarily expressed in the placenta and is essential for the immune tolerance of the fetus during pregnancy. Unlike many HLA genes, HLA G has relatively few variants and is alternatively spliced into seven different isoforms. Of these isoforms four are membrane-bound while three are predicted to be soluble. Both the membrane-bound and soluble form of HLA G can induce immune tolerance by binding to inhibitory receptors on various immune cells including macrophages and monocytes. HLA G is aberrantly expressed in diseases such as multiple sclerosis, viral infection, and cancer. In cancer HLA G is thought to function as an important mechanism to escape the immune system. Elevated HLA G is found in cancer patient serum and may serve as an important diagnostic tool to distinguish between malignant and benign tumors as well as sensitivity to chemotherapeutic agents.
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ATG12 - a ubiquitin-like protein essential for autophagosome assembly

Friday, May 15, 2015 - 07:58

Atg12 is a ubiquitin-like protein that plays an essential role in cellular homeostasis by regulating the degradation and recycling of cytoplasmic organelles and macromolecules. Atg12 is one of two ubiquitin-like protein systems that is required during the early steps of autophagosome formation. Upon the initiation of phagopore assembly Atg12 is activated by binding to the E1-like enzyme Atg7 and is then transferred to the E2 enzyme Atg10. Finally, Atg12 is conjugated to a lysine residue in Atg5 allowing the formation of a large multimeric complex with Atg16. This Atg12-Atg5-Atg16 complex localizes to the surface of the expanding phagopore where it functions as an E3 ligase for the lipidation of Atg8, the other autophagy-specific ubiquitin-like protein. Atg8, or LC3 in mammals, is conjugated to the lipid phosphatidylethanolamine and is...

CD74 - a central player in antigen presentation by MHC class II

Thursday, May 14, 2015 - 15:16

Cluster of differentiation 74 (CD74) is an important integral membrane protein that serves as a chaperone for MHC class II molecules. CD74, also known as the invariant chain or Ii, is needed for the proper folding and trafficking of MHC class II in antigen presenting cells. CD74 serves as a scaffold for MHC class II assembly. During assembly CD74 blocks the peptide binding cleft of MHC class II to prevent binding of antigenic peptides. Following endocytosis of antigen the CD74-MHC class II complex is trafficked to the endosome where CD74 is digested leaving only the 9 amino acid CLIP peptide in the binding cleft. CLIP peptide can then be released to allow the binding of antigenic peptide and the trafficking of the antigen bound MHC molecules to the plasma membrane. CD74 also plays important roles in various cell signaling pathways including the activation of nuclear factor-kB during B-cell maturation. CD74's function in B-cell...

Mucin 1 - a mucosal epithelial glycoprotein with importance in cancer diagnostics

Thursday, May 14, 2015 - 15:08

Mucin 1 (Muc1) is a heavily glycosylated protein that coats mucosal epithelial cells of the lungs, intestines, and other organs. Muc1 is thought to protect cells by binding to pathogens and responding to infections. During trafficking to the plasma membrane Muc1 is proteolytically cleaved in the endoplasmic reticulum to form a stable heterodimeric complex of two fragments. The smaller C-terminal region contains the cytoplasmic tail and transmembrane domain and is non-covalently bound to the larger glycosylated extracellular domain. Further cleavage or processing of the extracellular domain can cause release or shedding into the extracellular space and is thought to be involved in protein turnover and degradation or could potentially trigger a signaling response in the cytoplasmic domain. Muc1 is highly overexpressed in breast, ovarian, and prostate cancers and is correlated with metastasis and poor survival. Overexpressed Muc1 localizes throughout the cell in these...

Integrin Beta 1/CD29 - a cell adhesion and cell signaling protein with diverse functions

Thursday, May 14, 2015 - 13:42

Integrins are a large family of trasmembrane proteins involved in cell adhesion and form a link between the intracellular cyskeletal proteins and extracellular matrix proteins. Integrins exist as heterodimers consisting of alpha and beta subunits. In addition to cell adhesion these integrin complexes play key roles in diverse processes such as signal transduction, cell migration, proliferation, differentiation, and apoptosis. Integrins consist of three domains: the extracellular domain, the transmembrane domain, and the cytoplasmic tail. The large globular extracellular domain is responsible for ligand binding while the transmembrane region is a single-pass α-helix. The cytoplasmic tails are short unstructured regions that form salt bridges between alpha and beta proteins as well as interact with adaptor proteins that link to the cytoskeleton. Integrin complexes are able to signal bidirectionally. Ligand binding on the outside of the cell can trigger an intracellular...

hnRNP A1 - a ribonucleoprotein regulating gene expression at many levels

Wednesday, May 13, 2015 - 14:42

Heterogeneous nuclear ribonucleoprotein A1 (hnRNP A1) is an abundant ubiquitously expressed protein with important roles in the regulation of gene expression. hnRNP A1 is involved in transcription as well as the splicing, trafficking, and translation of RNA transcripts. hnRNP A1 binds RNA targets in a sequence specific manner through two N-terminal RNA recognition motifs (RRM) and a C-terminal RGG box RNA binding domain. During transcription hnRNPA1 binds to the promoter of target genes and has been shown to function as both a transcriptional activator and repressor. During the removal of introns hnRNP A1 is present in various splicing complexes and interacts with the essential splicing factor U2AF. hnRNP A1 also contributes to alternative splicing by modulating splice site selection. Once in the cytoplasm hnRNPA1 associates with internal ribosomal entry sites (IRES) of mature mRNA and can both inhibitor enhance translation depending on the...

Hsp90A - helping to fold a wide variety of signal transduction proteins

Monday, May 11, 2015 - 14:49

Heat-shock protein 90 (Hsp90) is a conserved ATP-dependent chaperone with diverse cellular functions. Hsp90 is ubiquitously expressed but is further induced upon cellular stress such as heat-shock or nutrient deprivation. Hsp90 is essential for the proper folding of a diverse set of proteins called clients. These client proteins consist of important signal transduction proteins including transcription factors, kinases, and steroid hormone receptors. By regulating the final folding steps of these client proteins Hsp90 plays an important role in many cellular signaling pathways. Hsp90 exists in two closely related isoforms; Hsp90A localizes to the cytosol while Hsp90B localizes to the endoplasmic reticulum. Hsp90A exists as a member of a protein complex and is associated with various co-chaperone proteins that mediate substrate recruitment. While the mechanism of protein folding is unclear an Hsp90A dimer is thought to bind to partially...

Bcl-2 - an antiapoptotic protein with an important role in cancer cell survival

Thursday, May 7, 2015 - 14:31

B-cell lymphoma 2 (Bcl-2) protein is an oncogene that normally acts as an apoptotic inhibitor and localizes to the mitochondrial membrane where it prevents the release of cytochrome c. The Bcl-2 protein family consists of over 20 proteins each containing at least one Bcl-2 homology (BH) domains and have either proapoptic or antiapoptotic activities. During induction of apoptosis the oligomerization of the Bcl-2 family proteins Bax and Bak forms a pore in the mitochondrial membrane triggering the release of cytochrome c. While it is still unclear, Bcl-2 is thought to directly bind and sequester BH-3 domain proapoptotic proteins such as BIM or BID. Upon release, BIM or BID are free to bind and activate Bax/Bak to induce cell death. Bcl-2 is often overexpressed in tumor cells where it can enhance cell survival despite the presence of apoptotic...

HIF-1 beta - activating gene transcription in response to hypoxia

Wednesday, May 6, 2015 - 14:43

Hypoxia-inducible factor 1 (HIF-1) is a heterodimeric transcription factor consisting of alpha and beta subunits. The levels of functional HIF-1 in the cell depends on the level of oxygen allowing cells to respond to hypoxic conditions. HIF-1α is a ubiquitously expressed protein containing an oxygen-dependent degradation domain that under normal conditions regulates its constant degradation. HIF-1 beta, on the other hand, is a stable constitutively expressed protein that localizes to the nucleus. Upon stabilization of HIF-1α by low oxygen it translocates to the nucleus where it dimerizes with HIF-1 beta to form an active transcription factor. HIF-1 recognizes and binds to hypoxia response elements (HRE) in the promoters of target genes including those involved in angiogenesis and cell proliferation such as vascular endothelial growth factor (VEGF) and ...

Atg9b - a marker for autophagosome induction and assembly

Monday, May 4, 2015 - 14:36

Atg9 is the only essential transmembrane protein involved in cellular autophagy. Autophagy regulates cellular homeostasis by allowing the turnover and recycling of misfolded proteins and damaged organelles. Formation of the double-membrane isolation membrane that forms the pre-autophagosome requires the contribution of highly mobile cytoplasmic vesicles containing Atg9. These vesicles are derived from recycling endosomes and are responsible for recruiting and delivering lipid components to the assembling autophagosome. Given this essential role in autophagosome assembly Atg9 is an excellent marker for the induction of autophagy and tracking membrane sources for formation of the autophagosome. In vertebrates Atg9 exists in two different isoforms: Atg9a and Atg9b. Atg9a is ubiquitously expressed while Atg9b is enriched in the placenta and the pituitary (1) and is induced by hypoxic conditions (2). Both proteins show similar localization in...

LC3/LC3B - measuring autophagosome formation and autophagic flux

Friday, May 1, 2015 - 13:12

Microtubule-associated protein-1 light chain 3 (LC3/LC3B) is a ubiquitin-like protein involved in the formation of the autophagosome. It is homologous to the yeast Atg8 protein. Autophagosomes are important for the degradation and recycling of intracellular cargo such as misfolded proteins or damaged organelles. Upon induction of autophagy, LC3 is conjugated to the lipid phosphatidylethanolamine (PE) by the Atg12-Atg5-Atg16 protein complex. This lipidation is essential for the localization of LC3 to the assembling autophagosome where it recruits the core autophagy machinery. LC3 mediates membrane expansion in order to selectively engulf cargo and deliver it to the lysosome for degradation. Autophagy receptors, such as p62/SQSTM1, recognize specific ubiquitinated cargo. They also contain LC3-interacting regions (LIR) which allow them to deliver cargo to the...

HIF-1 alpha - sensing and responding to changing oxygen levels

Thursday, April 30, 2015 - 14:53

Hypoxia-inducible factor 1 (HIF-1) allows cells to respond to changing levels of oxygen in the environment. HIF-1 is a heterodimeric transcription factor consisting of alpha and beta subunits. Under normal conditions HIF-1 alpha is continuously synthesized and degraded. HIF-1 alpha degradation is mediated through an oxygen-dependent degradation domain that is hydroxylated and leads to ubiquitylation and proteolysis. HIF-1 beta on the other hand is constitutively expressed and localizes to the nucleus. Under hypoxic conditions HIF-1alpha is stabilized and translocates to the nucleus where it dimerizes with HIF-1 beta. There it binds to hypoxia response elements (HRE) in the promoters of target genes involved in angiogenesis and cell proliferation including vascular endothelial growth factor (VEGF) and erythropoietin.  HIF-1 alpha also helps regulate cell metabolism under hypoxic conditions by controlling the...

mTOR - a central regulator of cell metabolism

Wednesday, April 29, 2015 - 15:05

The mammalian target of rapamycin (mTOR) signaling pathway allows cells to monitor environmental signals like nutrient availability and oxygen levels. mTOR is a phosphoinositide 3-kinase (PI3K)-related protein that assembles into large protein complexes (mTORC1 and mTORC2) capable of regulating cell metabolism, growth, and proliferation. mTOR complexes can be stimulated by extracellular growth factors such through the insulin and Ras signaling pathways as well as by intracellular signals such as the ratio of ATP:ADP within the cell or by amino acid levels. The tuberous sclerosis complex (TSC) is an important sensor module that integrates many of these signals and activates or inhibits mTOR accordingly. TSC acts as a GTPase-activating protein (GAP) for Rheb (Ras homolog enriched in brain), a direct interactor of the mTOR complex. GTP bound Rheb stimulates mTOR activity. However TSC negatively...

Survivin - an inhibitor of apoptosis protein

Monday, April 27, 2015 - 14:51

Survivin is an anti-apoptotic protein which is the smallest protein within a large family of proteins including X-linked IAP, c-IAP1 and 2, IAP-like protein-2, melanoma IAP, NAIP, and Livin. Survivin is responsible for a wide range of basic cellular functions that include the cell cycle regulation, fetal development, cell migration, and tumor progression. Xu et al from the MD Anderson Cancer Center used the survivin antibody to untangle apoptotic pathway components in promyelocytic leukemia by generating a comprehensive DNA microarray profile of target genes (1). Their detailed experiments allowed them to identify a novel PML4-dependent mechanism that ultimately downregulates survivin.

Survivin antibody

Western Blot: Survivin...

FANCD2 (Fanconi anemia subunit D2 protein)

Friday, April 24, 2015 - 14:27

Fanconi anemia (FANC) is a rare, autosomal-recessive genetic disorder that is a heterogeneous cancer susceptibility condition that manifests with a wide range of symptoms such as congenital malformations, deteriorating bone marrow failure, DNA-damage hypersensitivity, genomic instability, and increased cancer incidence. FANCD2 is a component within the protein complex that is involved in a cell's resistance to DNA cross-linking and subsequent DNA synthesis arrest that is stimulated by the insult of ionizing radiation (IR).

FANCD2 antibody

Western Blot: FANCD2 Antibody [NB100-182] - FANCD2 in HeLa WCE using NB 100-182 (lot C).

Immunoblotting and immunoprecipitation assays with the FANCD2 antibody allowed Park’s group to determine how processes such as oxidative stress and damage trigger the...

Beclin 1 - a key regulator of autophagosome formation

Thursday, April 23, 2015 - 14:43

The Beclin 1 protein is a central regulator of autophagy in mammalian cells. Autophagy is an essential process used to maintain cellular homeostasis by degrading and recycling cellular components such as damaged or worn out organelles and macromolecules. Autophagy is also activated in response to cellular stresses such as nutrient starvation or intracellular pathogens and can protect the cell from programmed cell death. Beclin 1 acts during the initiation stage of autophagy by forming the isolation membrane, a double-membrane structure that engulfs cytoplasmic material to form the autophagosome. Beclin 1 contains three structural domains: a BH-3 only domain, a central coiled-coil domain (CCD), and an evolutionarily conserved domain (ECD). These domains interact with a network of proteins involved in the regulation of autophagy. Under normal conditions the anti-apoptotic protein Bcl-2 inhibits autophagy...

CD11b, a marker of macrophages and microglia

Wednesday, April 22, 2015 - 13:51

The CD11 protein is actually a heterodimer complex that consists of CD11b and CD18. CD11 is involved in numerous adhesion-related associations between cells such as monocytes, macrophages, natural killer (NK) cells, and granulocytes. CD11 also regulates the uptake of complement-coated particles within cells. It is also gained usage as a microglial marker for tissues derived from the nervous system. Immunoblotting with the CD11b antibody from Wong's lab at Johns Hopkins demonstrates that the hypoxia-inducible factor 1 (HIF-1) drives breast cancer metastases by establishing a tumor-conducive lung niche microenvironment (intratumoral hypoxia and decreased collagen cross-linking) before secondary tumor cells seed to the distant locations (1). This same research group also used the CD11b antibody in later studies with the...

ATF6 - a key target in alcohol-induced fatty liver disease?

Monday, April 20, 2015 - 12:18
Untitled Document

The ATF6 endoplasmic reticulum (ER) stress-regulated transcription factor is constitutively expressed and plays a central role in the mammalian unfolded protein response (UPR). This fundamental pathway is responsible for balancing cellular homeostasis under stressful conditions resulting from environmental or physiological perturbations. The ATF6 molecule is anchored in the endoplasmic reticulum (ER) membrane when in its inactive form. Under conditions when a conversion to the ATF6 active form is required, ATF6 translocates to the Golgi and is cleaved by the S1P and S2P proteases. This intramembrane proteolytic event enables the translocation of the activated, N-terminal ATF6 component...

cIAP2 - balancing cell death and cell survival

Thursday, April 16, 2015 - 15:30

The inhibitor of apoptosis proteins (IAPs) are important regulators of cell death and inflammation. The cellular inhibitor of apoptosis protein 2 (cIAP2) contains three Baculovirus IAP repeat (BIR) domains, a Ubiquitin associated (UBA) domain, and a RING domain with E3 ligase activity. cIAP2 inhibits apoptosis through direct inhibition of the pro-apoptotic caspase-3. cIAP2 also regulates cell survival through its role in the tumor necrosis factor alpha (TNF-alpha) signaling pathway. TNF-alpha is an important cytokine that elicits a pro-inflammatory response through the activation of nuclear factor-kB (NF-kB). cIAP2 plays a crucial role downstream of the tumor necrosis factor receptor through the ubiquitylation of the effector protein RIP1 and by triggering the degradation of IkB alpha, a negative regulator of NF-kB, and...

ATG9A - early marker autophagosome assembly

Wednesday, April 15, 2015 - 14:53

ATG9A is the only essential integral membrane protein involved in autophagy. ATG9A contains six transmembrane domains and initiates the assembly of autophagosomes. The autophagosome is a double-membrane structure that engulfs and eventually degrades cytoplasmic materials such as organelles or macromolecules. Assembly of the autophagosome requires the delivery of lipids and membrane components to initiate and expand the double-membrane pre-autophagosome structure called the isolation membrane. ATG9A localizes to highly mobile cytoplasmic vesicles which are thought to play a key role in recruiting and delivering membrane and lipids to the assembling autophagosome. Interestingly ATG9A localizes only to the outer membrane layer of the double-membrane pre-autophagosome structure. This essential role in autophagosome assembly makes ATG9A an excellent marker for autophagy induction and for examining the membrane dynamics of early autophagosome...

BNIP3 - a regulator of mitochondrial autophagy and cell death

Monday, April 13, 2015 - 14:38

Bcl-2 nineteen-kilodalton interacting protein 3 (BNIP3) is a pro-apoptotic BH3-only protein. BNIP3 localizes to the mitochondrial membrane where it plays a key role in mitochondrial autophagy and cell death pathways. Similar to other Bcl-2 family members, BNIP3 binds to Bcl-2 and can activate the downstream effectors of Bax/Bak. However in contrast to the other family members, BNIP3 is a much weaker inducer of cell death and it is the transmembrane domain of BNIP3 that is responsible for this activity and not its BH3 domain. Depending on the cellular context BNIP3 can induce different forms of cell death including apoptosis, necrosis, and autophagy. BNIP3 can insert into the mitochondrial membrane and induce the opening of the mitochondrial permeability transition pore and eventually lead to necrosis. BNIP3 can also trigger the release of cytochrome c during apoptosis...

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