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Monoclonal Antibody Western Blotting Ubiquitin-Protein Ligase Activity

$260
100 µl
APPLICATIONS
REACTIVITY
Human, Monkey, Mouse, Rat

Application Methods: Immunoprecipitation, Western Blotting

Background: In mammalian cells, the significance of histone H2B ubiquitination in chromatin epigenetics came from the identification of the budding yeast protein Bre1 (1,2). Together with the ubiquitin-conjugating enzyme Rad6, Bre1 serves as the E3 ligase in the monoubiquitination of the yeast histone H2B within transcribed regions of chromatin (1-3). Subsequently, the mammalian orthologs of yeast Bre1, RNF20 and RNF40, were identified (4,5). These two proteins form a tight heterodimer that acts as the major E3 ligase responsible for histone H2B monoubiquitination at Lys120 in mammalian cells, a modification linked to RNA Pol II-dependent transcription elongation in undamaged cells. Researchers have shown that DNA double-strand breaks (DSBs) are also capable of inducing monoubiquitination of H2B. This process depends upon the recruitment to DSB sites, as well as ATM-dependent phosphorylation of the RNF20-RNF40 heterodimer, thus highlighting a role for this E3 ligase in DSB repair pathways (6). Indeed, investigators have shown that loss of RNF20-RNF40 function promotes replication stress and chromosomal instability, which may constitute an early step in malignant transformation that precedes cell invasion (7).

$293
100 µl
APPLICATIONS
REACTIVITY
Human, Monkey, Mouse, Rat

Application Methods: Chromatin IP, Immunoprecipitation, Western Blotting

Background: In mammalian cells, the significance of histone H2B ubiquitination in chromatin epigenetics came from the identification of the budding yeast protein Bre1 (1,2). Together with the ubiquitin-conjugating enzyme Rad6, Bre1 serves as the E3 ligase in the monoubiquitination of the yeast histone H2B within transcribed regions of chromatin (1-3). Subsequently, the mammalian orthologs of yeast Bre1, RNF20 and RNF40, were identified (4,5). These two proteins form a tight heterodimer that acts as the major E3 ligase responsible for histone H2B monoubiquitination at Lys120 in mammalian cells, a modification linked to RNA Pol II-dependent transcription elongation in undamaged cells. Researchers have shown that DNA double-strand breaks (DSBs) are also capable of inducing monoubiquitination of H2B. This process depends upon the recruitment to DSB sites, as well as ATM-dependent phosphorylation of the RNF20-RNF40 heterodimer, thus highlighting a role for this E3 ligase in DSB repair pathways (6). Indeed, investigators have shown that loss of RNF20-RNF40 function promotes replication stress and chromosomal instability, which may constitute an early step in malignant transformation that precedes cell invasion (7).

$260
100 µl
APPLICATIONS
REACTIVITY
Human, Monkey, Mouse, Rat

Application Methods: Immunoprecipitation, Western Blotting

Background: Smad ubiquitin regulatory factor 2 (Smurf2) is a HECT domain E3 ubiquitin ligase. It was initially identified as an inhibitor of TGF-β/BMP signaling by targeting R-Smads and TGF type I receptor for ubiquitination and degradation (1-3). Subsequent studies have revealed its role in neuronal and planar cell polarity, as well as in the senescence response and suppression of tumorigenesis (4-8). Smurf2 has a broad range of substrates including RUNX2, AMSH, Rap1B, and RNF11 (5,9-11). Smurf2 is widely expressed in various tissues. The C2 domain of Smurf2 inhibits its catalytic activity by interacting with the HECT domain (12). Research studies have shown that Smurf2 functions as a tumor suppressor by maintaining genomic stability through targeting RNF20 (13).

$260
100 µl
APPLICATIONS
REACTIVITY
Human, Mouse, Rat

Application Methods: Immunoprecipitation, Western Blotting

Background: ITCH is a HECT domain-containing E3 ubiquitin ligase, first identified in genetic studies of the mouse agouti locus, in which mutations result in characteristic coat color changes. One particular agouti mutation (non-agouti-lethal 18H) is notable for the development of immunological defects not observed in other agouti mutant mice; these include lymphoid hyperplasia and chronic stomach, lung and skin inflammation (manifest as constant itching). The 18H agouti mutation was traced to a chromosomal inversion that disrupted expression of an adjacent gene in the agouti locus, subsequently termed Itch to reflect the chronic itching phenotype (1-3).Further characterizations revealed that Itch encoded a NEDD4-like E3-ubiquitin ligase capable of catalyzing Lys29, Lys48, and/or Lys63-linked ubiquitination of target proteins, leading to their degradation by the proteosome pathway (4-6). The distinct phenotypes of Itch mutant mice led to the identification of an important regulatory role for ITCH-mediated ubiquitination in inflammatory signaling pathways. For example, ITCH-mediated ubiquitination of the transcription factor JunB was shown to play a direct inhibitory role in regulating expression of the proinflammatory cytokine IL-4. ITCH-null T lymphocytes consequently exhibit increased production of IL-4, leading to biased differentiation of naive CD4+ cells towards the proinflammatory Th2 lineage (7). In accordance with the findings from mutant Itch mouse models, a genetic linkage study in humans identified loss-of-function mutations in ITCH as a direct cause of syndromic multisystem autoimmune disease (SMAD) (8).Notably, targets of ITCH-mediated ubiquitination are not restricted to immune signaling pathways. For example, key mediators of the Hedgehog (9,10), Wnt/β-catenin (11), Hippo (12), and Notch signaling pathways (13,14) have been identified as important targets of ITCH-mediated ubiquitination (2).

$260
100 µl
APPLICATIONS
REACTIVITY
Human, Monkey, Mouse, Rat

Application Methods: Immunoprecipitation, Western Blotting

Background: Protein ubiquitination is an important posttranslational modification that regulates protein function and fate (1). Ubiquitin (Ub) can be conjugated to target proteins in either monomeric or polymeric forms. There are several different lysine residues within Ub that can be used as conjugation sites for poly-Ub chain formation. Different poly-Ub linkages mediate different functions of the target protein ranging from alterations in protein function to degradation (2). UBE2N/Ubc13 is a ubiquitin-E2-conjugating enzyme that catalyzes K63-linked poly-Ub chain formation (1,2). UBE2N forms a heterodimer with MMS2 or Uev1A to exert its E2 ligase function. The UBE2N/MMS2 and UBE2N/Uev1A heterodimers catalyze different modes of target protein ubiquitination to mediate various signaling pathways (3-5) including: DNA damage and recombination, p53 and check point control, the cell cycle (6-10), immunoreceptor signaling (11,12), and endocytosis (13). Most recently, UBE2N was shown to play an important role in inflammatory signaling by promoting K63-linked ubiquitination and activation of IKK downstream of the IL-1β receptor (14). Furthermore, interaction of UBE2N with the Triad1 E3 protein-ubiquitin ligase was shown to play an important role in myelopoiesis (15).

$260
100 µl
APPLICATIONS
REACTIVITY
Human, Monkey, Mouse, Rat

Application Methods: Western Blotting

Background: UBE3A, also commonly referred to as E6AP (E6 Associated Protein), is an E3 ubiquitin protein ligase and founding member of the HECT (Homologous to the E6 Carboxyl Terminus) family of E3 ligases (1). UBE3A has been shown to be hijacked by the oncogenic E6 protein of high-risk human papillomaviruses (HPV16 and HPV18) that causes the ubiquitination activity of UBE3A to be inappropriately directed toward several specific cellular proteins, the most notable of which, with respect to carcinogenesis, is p53 (2). Although the DNA-repair enzyme, HHR23A (human homolog A of Rad23), was the first described E6-independent substrate of UBE3A, very few E6-independent targets of UBE3A have been identified. This continues to be an active area of research, particularly because mutations or disruption in expression of UBE3A in the brain are the cause of Angelman syndrome (AS), a severe form of mental retardation (3-6). Although UBE3A is expressed in most human tissues from both parental alleles, it is expressed from the maternal allele in subregions of the brain, with the paternal allele being epigenetically silenced. AS is caused by disruptions in expression of the materal UBE3A allele, generally by large chromosomal deletion, but also by point mutations within the UBE3A coding sequence. This strongly suggests that lack of ubiquitination of one or more UBE3A substrates in neuronal tissue is responsible for the AS phenotype (7). Indeed, a recent study identified several new neuronal substrates of UBE3A including Arc and Ephexin-5 (8). The immediate early gene Arc (activity-regulated cytoskeleton-associated protein) is rapidly upregulated after robust neuronal stimulation and promotes internalization of AMPA-type glutamate receptors (AMPARs), resulting in reduction in synaptic strength. UBE3A ubiquitinates Arc and promotes its degradation by the 26S proteasome, thus preventing AMPAR internalization (8). Disruption in neuronal UBE3A function leads to an increase in Arc expression and a decrease in AMPARs at excitatory synapses, which may contribute to the neurological symptoms of AS.

$260
100 µl
APPLICATIONS
REACTIVITY
Human, Monkey, Mouse, Rat

Application Methods: Immunoprecipitation, Western Blotting

Background: Protein ubiquitination requires the concerted action of the E1, E2, and E3 ubiquitin-conjugating enzymes. Ubiquitin is first activated through ATP-dependent formation of a thiol ester with ubiquitin-activating enzyme E1. The activated ubiquitin is then transferred to a thiol group of ubiquitin-carrier enzyme E2. The final step is the transfer of ubiquitin from E2 to an ε-amino group of the target protein lysine residue, which is mediated by ubiquitin-ligase enzyme E3 (1).

$260
100 µl
APPLICATIONS
REACTIVITY
Human, Monkey, Mouse, Rat

Application Methods: Immunoprecipitation, Western Blotting

Background: Protein ubiquitination requires the concerted action of the E1, E2, and E3 ubiquitin-conjugating enzymes. Ubiquitin is first activated through ATP-dependent formation of a thiol ester with ubiquitin-activating enzyme E1. The activated ubiquitin is then transferred to a thiol group of ubiquitin-carrier enzyme E2. The final step is the transfer of ubiquitin from E2 to an ε-amino group of the target protein lysine residue, which is mediated by ubiquitin-ligase enzyme E3 (1).

$260
100 µl
APPLICATIONS
REACTIVITY
Human, Monkey, Mouse, Rat

Application Methods: Immunoprecipitation, Western Blotting

Background: Human E3 identified by differential display (UBR5/EDD) is a HECT domain-containing ubiquitin E3 ligase of the N-end rule pathway that promotes the ubiquitination and proteasomal degradation of proteins harboring N-degrons (1-3). UBR5 represents an ortholog of HYD, the Drosophila hyperplastic discs tumor suppressor gene product but has been found to be overexpressed in breast and ovarian cancers, suggesting a possible role in promoting tumor development (4,5). Research studies have demonstrated that UBR5 is functional within the nucleus as it participates in DNA damage signaling by controlling the activities of Chk2, TopBP1, and RNF168 (6-9). Recently, UBR5 was shown to play a novel role in immune cell function by regulating RORγt stability and IL-17 production by Th17 cells (10).

$111
20 µl
$260
100 µl
APPLICATIONS
REACTIVITY
Human, Mouse, Rat

Application Methods: Immunoprecipitation, Western Blotting

Background: Parkin is a protein of 465 amino acids with an amino-terminal ubiquitin domain and a carboxy-terminal RING-box (1). In the case of autosomal recessive juvenile Parkinsonism (AR-JP), deletions have been found in the gene on chromosome 6 encoding the protein Parkin (2).

$260
100 µl
APPLICATIONS
REACTIVITY
Human, Monkey, Mouse, Rat

Application Methods: Western Blotting

Background: The HECT domain-containing ubiquitin E3 ligase HECTH9 (also known as HUWE1, ARF-BP1, URE-B1, Mule, and LASU1) is critical for the ubiquitination and proteasomal degradation of many target proteins, and is involved in the regulation of a variety of cellular processes, including DNA replication and base excision repair, cellular proliferation, differentiation, and apoptosis. HECTH9 contains two Armadillo (ARM) repeat-like domains (ARLD1 and ARLD2), a ubiquitin-associated (UBA) domain, a WWE domain, a well-conserved BH3 domain, and a catalytic HECT domain that facilitates ubiquitination of target proteins. HECTH9 has been shown to polyubiquitinate p53 (1,2), Miz1 (3), N-Myc (4,5), Mcl-1 (6), Cdc 6 (7), and DNA polymerase beta (8) through K48-mediated linkage, thereby targeting these proteins for proteosomal degradation. The tumor suppressor protein ARF (known as p14 ARF in humans and p19 ARF in mice) binds to and inhibits the uibiquitin ligase activity toward p53, resulting in stabilization of p53 and induction of apoptosis (1). HECTH9 has also been shown to polyubiquitinate c-Myc through K63-linkage, which is required for recruitment of p300, activation of c-Myc target genes, and induction of cellular proliferation (9). HECTH9 is overexpressed in colon, lung, and breast cancer (1,9). In addition, defects in HECTH9 result in mental retardation syndromic X-linked Turner type (MRXST) and mental retardation X-linked type 17 (MRX17) syndromes (10).

$122
20 µl
$303
100 µl
APPLICATIONS
REACTIVITY
Human

Application Methods: Immunoprecipitation, Western Blotting

Background: The c-Cbl proto-oncogene is a ubiquitously expressed cytoplasmic adaptor protein that is especially predominant in hematopoietic cells (1,2). c-Cbl is rapidly tyrosine-phosphorylated in response to stimulation of a variety of cell-surface receptors and becomes associated with a number of intracellular signaling molecules such as protein tyrosine kinases, phosphatidylinositol-3 kinase, Crk, and 14-3-3 proteins (3,4). c-Cbl possesses a highly conserved amino-terminal phosphotyrosine binding domain (TKB) and a C3HC4 RING finger motif. The TKB recognizes phosphorylated tyrosines on activated receptor tyrosine kinases (RTKs) as well as other nonreceptor tyrosine kinases. The RING finger motif recruits ubiquitin-conjugating enzymes. These two domains are primarily responsible for the ubiquitin ligase activity of c-Cbl and downregulation of RTKs (3). Research studies have indicated that in human cancer tissues, c-Cbl is frequently tyrosine-phosphorylated in a tumor-specific manner (5). Phosphorylation of Tyr731 of c-Cbl provides a docking site for downstream signaling components such as p85 and Fyn (6).

$260
100 µl
APPLICATIONS
REACTIVITY
Human, Monkey, Mouse, Rat

Application Methods: Immunohistochemistry (Paraffin), Immunoprecipitation, Western Blotting

Background: RING-box protein 1 (RBX1 or ROC1) is an essential component of two distinct but structurally related E3 ubiquitin ligase complexes, the SCF complex and the CBC (VHL) complex (1). RBX1 mediates the neddylation of CUL1, which activates SCF E3 ligase by facilitating the ubiquitin transfer from E2 to substrates (2-4). The RING finger domain of RBX1 is required for ubiquitin ligation (5). Two evolutionarily conserved mammalian RBX family members, RBX1/ROC1 and RBX2/ROC2/SAG, have been identified (5). RBX1 is constitutively expressed and binds to CUL2/VHL, while stress-inducible RBX2 binds to CUL5/SOCS (6).

$303
100 µl
APPLICATIONS
REACTIVITY
Human, Mouse, Rat

Application Methods: Immunoprecipitation, Western Blotting

Background: Neural precursor expressed, developmentally down-regulated protein 4 (NEDD4) was originally identified as a gene that is highly expressed in the early mouse embryonic central nervous system (1). Subsequently, a family of NEDD4-like proteins have been defined that includes seven members in humans (2). NEDD4 and NEDD4-like (NEDD4L) proteins contain multiple functional domains including a calcium-dependent phospholipid and membrane binding domain (C2 domain), two to four protein binding domains (WW domains), and an E3 ubiquitin-protein ligase domain (HECT domain). NEDD4 and NEDD4L have been shown to downregulate both neuronal voltage-gated Na+ channels (NaVs) and epithelial Na+ channels (ENaCs) in response to increased intracellular Na+ concentrations (3,4). The WW domains of NEDD4 bind to PY motifs (amino acid sequence PPXY) found in multiple NaV and ENaC proteins; ubiquitination of these proteins is mediated by the HECT domain of NEDD4 and results in their internalization and removal from the plasma membrane. Research studies have shown that mutation of the PY motifs in ENaC proteins is associated with Liddle's syndrome, an autosomal dominant form of hypertension (5). In addition to targeting sodium channels, NEDD4L has also been shown to negatively regulate TGF-β signaling by targeting Smad2 for degradation (6). Mouse and human NEDD4 are rapidly cleaved by caspase proteins during apoptosis, although the significance of this cleavage is not clear (7).

$260
100 µl
APPLICATIONS
REACTIVITY
Human

Application Methods: Immunoprecipitation, Western Blotting

Background: In mammalian cells, the significance of histone H2B ubiquitination in chromatin epigenetics came from the identification of the budding yeast protein Bre1 (1,2). Together with the ubiquitin-conjugating enzyme Rad6, Bre1 serves as the E3 ligase in the monoubiquitination of the yeast histone H2B within transcribed regions of chromatin (1-3). Subsequently, the mammalian orthologs of yeast Bre1, RNF20 and RNF40, were identified (4,5). These two proteins form a tight heterodimer that acts as the major E3 ligase responsible for histone H2B monoubiquitination at Lys120 in mammalian cells, a modification linked to RNA Pol II-dependent transcription elongation in undamaged cells. Researchers have shown that DNA double-strand breaks (DSBs) are also capable of inducing monoubiquitination of H2B. This process depends upon the recruitment to DSB sites, as well as ATM-dependent phosphorylation of the RNF20-RNF40 heterodimer, thus highlighting a role for this E3 ligase in DSB repair pathways (6). Indeed, investigators have shown that loss of RNF20-RNF40 function promotes replication stress and chromosomal instability, which may constitute an early step in malignant transformation that precedes cell invasion (7).

$260
100 µl
APPLICATIONS
REACTIVITY
Human

Application Methods: Immunoprecipitation, Western Blotting

Background: Protein ubiquitination requires the concerted action of the E1, E2, and E3 ubiquitin-conjugating enzymes. Ubiquitin is first activated through ATP-dependent formation of a thiol ester with ubiquitin-activating enzyme E1. The activated ubiquitin is then transferred to a thiol group of ubiquitin-carrier enzyme E2. The final step is the transfer of ubiquitin from E2 to an ε-amino group of the target protein lysine residue, which is mediated by ubiquitin-ligase enzyme E3 (1).Ubiquitin conjugating-enzyme 2T (UBE2T) is an E2 family member responsible for the ATP-dependent ubiquitin tagging of target proteins for degradation. Research studies indicate that UBE2T plays an important role in the Fanconi anemia pathway and that UBE2T expression is required for normal DNA repair through this pathway. Interaction between UBE2T and FANCL appears to stimulate UBE2T auto monoubiquitination, leading to UBE2T inactivation and negative regulation of the Fanconi anemia pathway (2-4). Additional research details upregulation of UBE2T expression in breast cancer cells and certain lung carcinomas, suggesting a possible involvement in these malignancies (5,6).

$260
100 µl
APPLICATIONS
REACTIVITY
Human

Application Methods: Immunofluorescence (Immunocytochemistry), Immunoprecipitation, Western Blotting

Background: MDM2, a ubiquitin ligase for p53, plays a central role in regulation of the stability of p53 (1). Akt-mediated phosphorylation of MDM2 at Ser166 and Ser186 increases its interaction with p300, allowing MDM2-mediated ubiquitination and degradation of p53 (2-4). Phosphorylation of MDM2 also blocks its binding to p19ARF, increasing the degradation of p53 (3).

$260
100 µl
APPLICATIONS
REACTIVITY
Human

Application Methods: Chromatin IP, Flow Cytometry, Immunohistochemistry (Paraffin), Immunoprecipitation, Western Blotting

Background: The transcriptional intermediary factor 1 (TIF1) family represents a group of proteins with multiple histone-binding domains. In humans, this family comprises four proteins, TIF1α/TRIM24, TIF1β/TRIM28/KAP1, TIF1γ/TRIM33/Ectodermin, and TIF1δ/TRIM66, which are characterized by an amino-terminal tripartite motif (TRIM) domain consisting of a RING domain, two B boxes, a coiled-coil domain, and a carboxy-terminal PHD finger and bromodomain (1). Despite their similar overall structure, these proteins have diverse roles in transcriptional regulation. TIF1α functions as a ligand-dependent nuclear receptor coregulator and more recently has been implicated in regulating p53 stability (2). TIF1β is an intrinsic component of the N-CoR1 corepressor complex and the NuRD nucleosome-remodeling complex (3) and functions as a corepressor for Kruppel-associated box (KRAB) zinc-finger transcription factors (4). Furthermore, TIF1β promotes heterochromatin-mediated gene silencing formation by serving as a cofactor for heterochromatin protein HP1 (5). TIF1δ expression is restricted to the testis and has been shown to interact with HP1γ (6).

$260
100 µl
APPLICATIONS
REACTIVITY
Human, Monkey, Mouse, Rat

Application Methods: Immunoprecipitation, Western Blotting

Background: The carboxy terminus of Hsc70-interacting protein (CHIP, STUB1) is a co-chaperone protein and functional E3 ubiquitin ligase that links the polypeptide binding activity of Hsp70 to the ubiquitin proteasome system (1). Cytoplasmic CHIP protein contains three 34-amino acid TPR (tetratricopeptide repeat) domains at its amino terminus and a carboxy-terminal U-box domain. CHIP interacts with the molecular chaperones Hsc70-Hsp70 and Hsp90 through its TPR domain, while E3 ubiquitin ligase activity is confined to the U-box domain (2,3). The binding of CHIP to Hsp70 can stall the folding of Hsp70 client proteins and concomitantly facilitate the U-box dependent ubiquitination of Hsp70-bound substrates (4-6). CHIP appears to play a central role in cell stress protection (7) and is responsible for the degradation of disease-related proteins that include cystic fibrosis transmembrane conductance regulator (4), p53 (8), huntingtin and Ataxin-3 (9), Tau protein (10), and α-synuclein (11).

$260
100 µl
APPLICATIONS
REACTIVITY
Human, Monkey, Mouse, Rat

Application Methods: Immunoprecipitation, Western Blotting

Background: Protein ubiquitination requires the concerted action of the E1, E2 and E3 ubiquitin-conjugating enzymes. Ubiquitin is first activated through an ATP-dependent formation of a thiol ester with an E1 enzyme. The activated ubiquitin is then transferred to a thiol-group of an E2 ubiquitin-conjugation enzyme. The final step is the transfer of ubiquitin from E2 to an ε-amino group of a lysine residue on the target protein, a transfer mediated by ubiquitin-conjugating enzyme E3 (1). UbcH5C is a universally expressed E2 ubiquitin conjugating enzyme and member of the UbcH5 family that also includes UbcH5A and UbcH5B (2). Evidence suggests that UbcH5C plays an important role in regulating a number of signaling pathways by catalyzing the ubiquitination of key target proteins, including p53, PCNA, the IκB kinase protein NEMO, and the apoptosis inhibitor BRUCE (3-6). Gene expression profiles revealed increased expression of UbcH5C in meibomian cell carcinoma and oncocytic thyroid adenomas (7,8), while an RNAi screen reveals diffrential Ubc5HC in acute promyelocytic cells (9). These results suggest a potential role of UbcH5C in cell cycle control and tumorigenesis.