TY - JOUR. T1 - Modulating cellular balance of Rps3 mono-ubiquitination by both Hel2 E3 ligase and Ubp3 deubiquitinase regulates protein quality control. AU - Jung, Youjin. AU - Kim, Hag Dong. AU - Yang, Hee Woong. AU - Kim, Hye Jin. AU - Jang, Chang Young. AU - Kim, Joon. PY - 2017/11/3. Y1 - 2017/11/3. N2 - When a ribosome complex is stalled during the translation elongation process in eukaryotes, the mono-ubiquitination of Rps3 has recently been shown to be critical to ribosome quality control. We have discovered that the regulatory role of Rps3 mono-ubiquitination is controlled by a deubiquitinase. We also showed that an autophagic signal appears to be coupled to the mono-ubiquitination of Rps3p through the entrance of Ubp3p into the autophagosome in yeasts. The mono-ubiquitination of the Rps3 protein is tightly modulated by reciprocal action between the Hel2p E3 ligase and the Ubp3p deubiquitinase in yeasts and the reciprocal action between the RNF123 E3 ligase and the USP10 deubiquitinase ...

May be involved in nucleotide excision repair (By similarity). Binds and presumably selects ubiquitin-conjugates for destruction. Prefers multiubiquitin chains rather than single ubiquitins, with a binding affinity for Lys-48-linked ubiquitin chains. Acts as a ubiquitin receptor that associates with the 26S proteasomal docking subunit RPN10 for the indirect recognition of ubiquitinated substrates of ubiquitin/26S proteasome-mediated proteolysis (UPP).

PDCD5 mediates ubiquitin-dependent proteasomal degradation of HDAC3 via C-terminal cleavage of HDAC3.(a) MG132 treatment induces accumulation of cleaved HDAC3.

Protein turnover is crucial in maintaining cellular homeostasis and this process is largely controlled by the Ubiquitin Proteasome Pathway (UPP). The pathway consists of an enzymatic cascade that links the polypeptide cofactor Ubiquitin to specific protein targets, which mark them for degradation by the proteasome. This cascade is highly regulated and impacts virtually all cellular processes including cell cycle progression, cell proliferation, cell differentiation and apoptosis. Malfunction of the UPP has been implicated in the development of diseases such as cancer, immune disorders and neurodegeneration. ...

Research in the field of ubiquitin proteasome is expanding exponentially. For instance, intensive research is going on in the field of applications of ubiquitin proteasome system in the treatment of cancer, as the pharmacological inhibition properties of proteasomes can be effective in cancer treatment. Potential sites of therapeutic interventions are also under research and the selective inhibition of disease specific components is also being studied for the purpose of developing treatments for diseases such as neurodegenerative disorders. This indicates a bright future market potential depending upon the time required for commercialization. Currently, there is only one approved ubiquitin proteasome system product available in the market named Velcade. In 2009, total sales of Velcade were estimated to be 1.4 billion and being the only approved drug, its sales are expected to achieve growth at a high compounded annual growth rate ...

TY - JOUR. T1 - Stable ester conjugate between the Saccharomyces cerevisiae RAD6 protein and ubiquitin has no biological activity. AU - Sung, Patrick. AU - Prakash, Satya. AU - Prakash, Louise. PY - 1991/10/5. Y1 - 1991/10/5. N2 - The RAD6 gene of Saccharomyces cerevisae, which encodes a ubiquitin-conjugating enzyme, is required for DNA repair, DNA damage-induced mutagenesis and sporulation. To evaluate the biological relevance of the thioester adduct between RAD6 protein and ubiquitin, formed as an obligatory, transient intermediate during ubiquitin conjugation to substrates, we 3ltered cysteine 88 in RAD6 to serine. Esterification with ubiquitin occurs at serine 88 in the mutant protein, but conjugation of ubiquitin to the test substrate histone H2A is inactivated. Phenotypically, strains harboring the rad6 Ser88 allele are indistinguishable from rad6 deletion (rad6Δ) mutant cells. These findings argue against ligation of ubiquitin at cysteine 88 acting as a functional switch of a cryptic ...

CIECHANOVER, Aaron. Intracellular protein degradation: from a vague idea through the lysosome and the ubiquitin-proteasome system and onto human diseases and drug targeting. Medicina (B. Aires) [online]. 2010, vol.70, n.2, pp. 105-119. ISSN 0025-7680.. Between the 1950s and 1980s, scientists were focusing mostly on how the genetic code is transcribed to RNA and translated to proteins, but how proteins are degraded has remained a neglected research area. With the discovery of the lysosome by Christian de Duve it was assumed that cellular proteins are degraded within this organelle. Yet, several independent lines of experimental evidence strongly suggested that intracellular proteolysis is largely non-lysosomal, but the mechanisms involved remained obscure. The discovery of the ubiquitin-proteasome system resolved the enigma. We now recognize that degradation of intracellular proteins is involved in regulation of a broad array of cellular processes, such as cell cycle and division, regulation of ...

F-box proteins serve as mediators in targeting bound target proteins for ubiquitination and destruction. The ubiquitin-dependent proteolytic pathway plays a key role in the regulation of various short-lived proteins involved in diverse cellular processes in eukaryotes including cell cycle progression, morphogenesis, signal transduction and transcription regulation[11, 12]. The primary function of the ubiquitin-dependent proteolytic system is the tagging of substrate proteins with ubiquitin, i.e. covalent attachment of multiple ubiquitin molecules, which allows the proteasome, a 26S protease complex, to recognize and degrade target proteins. This process involves several main steps: (1) activation of ubiquitin in a thioester linkage with ubiquiin-activating enzyme (E1); (2) ransfer of activated ubiquitin from E1 to active site cysteine of one of many ubiquitin-conjugated enzymes (E2s); and finally, (3) conjugation of ubiquitin mainly to acceptor lysine residue of the target protein forming the ...

The attachment of one or more ubiquitin moieties to proteins plays a central regulatory mechanism in eukaryotic cells. Protein ubiquitylation regulates numerous cellular processes, including protein degradation, signal transduction, DNA repair and cell division. The characterization of ubiquitylation is a two-fold challenge that involves the mapping of ubiquitylation sites and the determination of ubiquitin chain topology. This review focuses on the technical advances in the mass spectrometry-based characterization of ubiquitylation sites, which have recently involved the large-scale identification of ubiquitylation sites by peptide-level enrichment strategies. The discovery that ubiquitylation is a widespread modification similar to phosphorylation and acetylation suggests cross-talk may also occur at the post translational modification level ...

Alexander Varshavsky, Caltechs Thomas Hunt Morgan Professor of Biology, has received the 2017 Heinrich Wieland Prize from the Boehringer Ingelheim Foundation. The prize, named after the late Nobel Laureate Heinrich Wieland, honors outstanding research on biologically active molecules and systems in the fields of chemistry, biochemistry, and physiology as well as their clinical importance.. Varshavsky was recognized for his work on the biology of the ubiquitin system, a large set of molecular pathways that have in common a small protein called ubiquitin. A major function of the ubiquitin system is the regulated degradation of cellular proteins. The ubiquitin system targets for selective destruction not only misfolded or otherwise abnormal proteins, but also normal proteins that have evolved to be short-lived, depending on specific physiological conditions. The destruction of such proteins underlies a multitude of biological processes, including cell growth and division, cell differentiation, ...

Ubiquitin received its name because of its ubiquitous expression in eukaryotic cells. Since its discovery more than 40 years ago, the covalent attachment of ubiquitin to proteins has become well established as a degradative signal. However, more recently it has become clear that protein degradation is only one of many processes regulated by ubiquitylation and it has emerged that this 76 amino acid protein is also crucial for the regulation of numerous cellular processes. For example, ubiquitin is also involved in endocytosis, membrane trafficking, DNA repair, and the regulation of signalling pathways and the cell cycle. In this issue, we conclude our Ubiquitin Minifocus with three articles that provide further insight into the diverse roles of ubiquitylation. E3 ubiquitin ligases are central to the post-translational modification of proteins with ubiquitin and - in a Cell Science at a Glance article (p. 531) - Meredith Metzger, Ventzislava Hristova and Allan Weissman provide an overview of the ...

E3 ubiquitin ligases have a significant role in carcinogenesis and include a large family of proteins that catalyze the ubiquitination of many protein substrates for targeted degradation by the 26S proteasome. ubiquitin ligases for GC are discussed IPI-493 in the review. (a very interesting new gene) fingers IPI-493 and U-box domains[21]. There are about 30 proteins containing the HECT domain. The fingers and U-box quitin ligases contain the new gene (finger domain but only a small part functions as an E3 ubiquitin ligase. Unlike RING proteins most HECT proteins if not all are believed to function as E3 ubiquitin ligases. RING and HECT E3 ubiquitin ligases use different catalytic mechanisms to promote the transfer of ubiquitin to targeted substrates. RING E3 ubiquitin ligases can promote the direct transfer of ubiquitin from E2 to the targeted substrate whereas HECT E3 ubiquitin ligases interact with the cognate E2 followed by the formation of a thiolester linkage with ubiquitin and subsequent ...

FUNCTION: This gene encodes a protein that is a member of the ubiquitin C-terminal hydrolase subfamily of the deubiquitinating enzyme family. Members of this family catalyze the removal of ubiquitin from a substrate or another ubiquitin molecule and thereby play important roles in regulating signaling pathways, recycling ubiquitin and regulating protein stability. This protein removes ubiquitin from K-63-linked ubiquitin chains from proteins involved in NF-kappaB signaling and thus acts as a negative regulator of this pathway. In humans mutations in this gene have been associated with cylindromatosis, an autosomal dominant predisposition to tumors of skin appendages. In mouse deficiency of this gene impairs thymocyte development and increases susceptibility to skin and colon tumors. A pseudogene of this gene has been identified on chromosome 1. Alternative splicing results in multiple transcript variants that encode different protein isoforms. [provided by RefSeq, Jan 2013 ...

Polyubiquitin chains are composed of ubiquitin monomers that are covalently linked through isopeptide bonds (other than linear, or Met1-linked polyubiquitin). Isopeptides are formed between a lysine residue of one Ubiquitin molecule and the C--terminal glycine residue of another Ubiquitin molecule. Seven of the seventy-six amino acids in ubiquitin are lysine residues that can participate in polyubiquitin chain formation. Linkage through specific lysine residues is thought to serve as a signal that affects protein degradation, signaling, trafficking, and other cellular processes. K48-linked polyubiquitin chains attached to substrate proteins often serve as a recognition sequence for targeting and destruction of the substrate by the 26S Proteasome. This antibody detects the K48 linkage. It does not detect monoubiquitin or ubiquitin liked via any other lysine residue. Reactivity across all species is anticipated. ...

Anti-Mono and Polyubiquitylated Conjugates mAb (FK2) HRP-linked Antibody Activity Assay: The activity of the anti-mono and polyubiquitylated conjugates mAb (FK2) HRP-linked antibody was tested for its ability to recognise mono and polyubiquitin conjugates (Lanes 2 and 3) but not free ubiquitin (Lane1). By Western blotting the specific recognition of mono and polyubiquitin conjugates by the antibody over free ubiquitin was demonstrated (Figure 1). In a priming and extension assay containing, UBE1 [6His-tagged] (Cat# 61-0001), UBE2W [6His-tagged] (Cat# 62-0085), UBE2N [untagged] (Cat# 62-0047), UBE2V1 [untagged] (Cat# 62-0059), Ubiquitin (Cat# 60-0001), CHIP [untagged] (Cat# 63-0003) and ATP. Using the anti mono and polyubiquitylated conjugates mAb (FK2) HRP-linked antibody, detection of polyubiquitin chains extending from mono-ubiquitylated CHIP (Lane 1) and free chains generated by UBE2N/UBE2V1 in the presence of CHIP (Lane 3) were observed. In the absence of CHIP, only the background detection ...

In recent years a superfamily of ubiquitin-like domains has been identified [30]. This superfamily can be divided into the ubiquitin-like proteins (UBLs), which consist solely of the ubiquitin-like domain, and ubiquitin domain proteins (UDPs), which are larger proteins containing one or more ubiquitin-like domains. To our knowledge DWNN is the first example of a ubiquitin-like domain that is alternatively expressed both as a UBL and as a UDP.. Ubiquitin-like proteins typically share the C-terminal GG motif, which acts as a recognition motif for a protease that cleaves between the two glycines, initiating the process of conjugation. The occurrence of the GG motif in the structurally identical position in human and mouse DWNN domains (highlighted in pink in Figure 4D) suggests that the domain may be involved in a similar process of conjugation, which we may call DWNNylation. As in the case of ubiquitin, the GG lies outside of the structured region, as can be clearly seen in Figure 5B. The ...

Doss-Pepe, E.W., et al. (2003). Ataxin-3 interactions with Rad23 and valosin-containing protein and its associations with ubiquitin chains and the proteasome are consistent with a role in ubiquitin-mediated proteolysis. Mol. Cell. Biol 23(18): 6469-6483. ...

Deubiquitinating proteases reverse protein ubiquitination and rescue their target proteins from destruction by the proteasome. USP2, a cysteine protease and a member of the ubiquitin specific protease family, is overexpressed in prostate cancer and stabilizes fatty acid synthase, which has been associated with the malignancy of some aggressive prostate cancers. Here, we report the structure of the human USP2 catalytic domain in complex with ubiquitin. Ubiquitin uses two major sites for the interaction with the protease. Both sites are required simultaneously, as shown by USP2 inhibition assays with peptides and ubiquitin mutants. In addition, a layer of ordered water molecules mediates key interactions between ubiquitin and USP2. As several of those molecules are found at identical positions in the previously solved USP7/ubiquitin-aldehyde complex structure, we suggest a general mechanism of water-mediated ubiquitin recognition by USPs ...

Phytohormone abscisic acid (ABA) regulates key processes in plants relative to seed germination, plant development and responses to important environmental stresses, such as drought, salinity and extreme temperatures. ABA perception is tightly controlled by the ubiquitin proteasome system. CRL4-CDDD E3 ubiquitin ligases target ABA receptors of the PYR/PYL/RCAR (pyrabactin resistance/pyrabactin resistance-like/regulatory components of ABA) family, triggering their ubiquitination and proteasomal degradation. Therefore, CRL4-CDDD complexes function as repressors of ABA-mediated stress responses. On the contrary, ABA treatment attenuates receptor degradation although the precise molecular details of this mechanism have remained unknown. In this seminar, our most recent data on the regulatory process underlying ABA-mediated protection of PYR/PYL/RCAR receptors, by CRL4-CDDD E3 ubiquitin ligases inactivation, will be shown.. ...

In the ubiquitin-mediated pathway for the degradation of intracellular proteins, several molecules of ubiquitin are linked to the protein substrate by amide linkages. It was noted that the number of ubiquitin-protein conjugates and their apparent molecular size are higher than expected from the number of amino groups in the protein. When the amino groups of ubiquitin were blocked by reductive methylation, it was efficiently conjugated to lysozyme, but the higher-molecular-weight conjugates were not formed. This suggests that the higher-molecular-weight conjugates with native ubiquitin contain structures in which one molecule of ubiquitin is linked to an amino group of another molecule of ubiquitin. Methylated ubiquitin stimulated protein breakdown at about one half the rate obtained with native ubiquitin, and isolated conjugates of 125I-lysozyme with methylated ubiquitin were broken down by reticulocyte extracts. These findings indicate that the formation of polyubiquitin chains is not ...

Exit from mitosis requires the degradation of regulatory proteins including the mitotic cyclins and securin through ubiquitination by the anaphase promoting complex bound to Cdc20 or Cdh1. Cdc20-APC is regulated through inhibition by the spindle assembly checkpoint protein MAD2. Knowledge of Cdh1-APC regulation is limited to the phosphorylation-dependent dissociation of Cdh1 from APC. A novel means of regulating Cdh1 by the MAD2-related gene, MAD2L2, is reported. MAD2L2 specifically binds and inhibits Cdh1-APC, paralleling the effect of MAD2 on Cdc20. It is suggested that MAD2L2 and MAD2 inhibit the release of substrates from APC and a mechanism of inhibition is proposed (Pfleger, 2001a). The specificity of ubiquitin-mediated protein degradation with regard to the selection of substrates to be polyubiquitinated has only been determined rather recently. Substrate targeting by the N-end rule and HECT (homology to E6AP carboxyl terminus) domain ubiquitin ligases occurs through substrate-specific ...

The selective degradation of many proteins in eukaryotic cells is carried out by the ubiquitin system. In this pathway, proteins are targeted for degradation by covalent ligation to ubiquitin, a highly conserved protein [1]. Ubiquitylated proteins were degraded by the 26S protea-some in an ATP-depended manner. The degradation of ubiquitylated proteins were controlled by isopeptidase cleavage. A well characterised system of ubiquitylation and deubiquitylation is the calmodulin system in vitro [2]. Detection of ubiquityl-calmodulin conjugtates in vivo have not been shown so far. In this article we discuss the detection of ubiquitin calmodulin conjugates in vivo by incubation with a novel high-molecular weight ubiquitylprotein-isopeptidase in rabbit tissues. Proteins with a molecular weight of ubiquityl-calmodulin conjugates could be detected in all organs tested. Incubation with ubiquitylprotein-isopeptidase showed clearly a decrease of ubiquitin calmodulin conjugates in vivo with an origination of

The majority of eukaryotic proteins are degraded by the ubiquitin-proteasome system. In this pathway, cytosolic substrates are first earmarked for degradation by modification with ubiquitin (ubiquitylation) and subsequently degraded by the 26S pro-teasome, a large protease residing in both the cytosol and the nucleus. ER-resident proteins are similarly degraded but take the route of a specialized pathway coined ER-associated degradation (ERAD). In order to reach the cytosolic ubiquitin/proteasome system, these substrates must first relocate from the ER to the cytosol, possibly with the help of protein conducting membrane channels. Previous work has shown that specific ubiquitin-conjugating enzymes (e.g. Ubc6, Ubc7) and ubiquitin ligases (e.g. Hrd1) con-tribute to ERAD, but how the substrates reach the proteasome remained to be clarified. Besides its function as a quality control system in recognizing and eliminating aberrant proteins, ERAD appears also to play a part in regulatory pathways. ...

Covalent attachment of ubiquitin (Ub) or SUMO to DNA repair proteins plays critical roles in maintaining genome stability. These structurally related polypeptides can be viewed as distinct road signs, with each being read by specific protein interaction motifs. Therefore, via their interactions with selective readers in the proteome, ubiquitin and SUMO can elicit distinct cellular responses, such as directing DNA lesions into different repair pathways. On the other hand, through the action of the SUMO-targeted ubiquitin ligase (STUbL) family proteins, ubiquitin and SUMO can cooperate in the form of a hybrid signal. These mixed SUMO-ubiquitin chains recruit

The SIAH1 gene encodes a RING-type E3 ubiquitin ligase belonging to the Seven in Absentia Homolog (SIAH) family. The enzyme carries out the ubiquitination of a wide variety of targets, either by direct binding or by acting as the essential RING domain subunit for larger E3 ubiquitin ligase complexes. By carrying out its function, the protein marks its targets for proteasomal degradation. Target substrates of SIAH1 include transcription regulators such as ELL2, MYB, POU2AF1, PML and RBBP8, the signal transduction molecules TIEG1 and NUMB, the cell surface receptor DCC and the anti-aopoptotic protein BAG1. It also ubiquitinates SYP, a protein involved in synaptic vesicle function in neurons. The protein is thus involved in the regulation of several key biological processes such as apoptosis, axon guidance, cell cycle, spermatogenesis and nervous system development. ...

Because NF-κB pathways make key contributions to host defense mechanisms, the activation of NF-κB is tightly controlled by endogenous regulators acting at several sites. Ubiquitination regulates at least four steps in NF-κB pathways, including targeting IκBα for degradation, processing of NF-κB precursors to produce p50/p52 subunits of NF-κB, and activation of kinases such as receptor-interacting protein or the regulatory subunit of the IKK complex IKKγ (NEMO) and activation of TRAF-family adapter proteins (TRAF2, TRAF6) (9, 35, 36). Ubiquitin is a 76-aa protein that is covalently attached to target proteins through an isopeptide bond, between the C terminus of ubiquitin and the ε-amino group of a lysine residue in the target proteins (9, 37). Ubiquitin contains seven lysine residues, but ubiquitin chains linked on Lys48 and Lys63 are the best characterized, to date. Whereas Lys48-linked polyubiquitin chains represent a signal for proteosomal degradation of modified substrates such as ...

Ubiquitin is an 8.5 kDa post-translational modifier involved in essentially all eukaryotic cellular processes. Through a process called ubiquitination, ubiquitinating enzymes chemically attach ubiquitin to substrate proteins to control their fates, resulting in anything from their recruitment into signaling pathways to their proteasomal degradation, with a plethora of possibilities in between. Ubiquitin molecules can also be attached to one another, resulting in poly-ubiquitin chains with various effects depending on the number of ubiquitin molecules and the specific amino acid residues used to link them together. While most poly-ubiquitin in the cell exists as conjugated species, there are also untethered poly-ubiquitin species that are not attached to substrates. These unanchored ubiquitin chains have been previously classified as toxic byproducts that interfere with proteasomal function in vitro and in yeast, and are thus believed to be disassembled rapidly to avoid toxicity. Conversely, several

A protein degradation pathway is found at the inner nuclear membrane that is distinct from, but complementary to, endoplasmic-reticulum-associated protein degradation, and which is mediated by the Asi protein complex; a genome-wide library screening of yeast identifies more than 20 substrates of this pathway, which is shown to target mislocalized integral membrane proteins for degradation. The endoplasmic-reticulum-associated protein degradation (ERAD) pathway mediates protein homeostasis in cells by tagging misfolded proteins of the ER with the protein ubiquitin. Ubiquitylated proteins are subsequently degraded within the cytoplasm. The nuclear membrane is continuous with the ER membrane, prompting Michael Knop and colleagues to ask whether protein quality control also operates in the inner nuclear membrane (INM). The authors find that there is a protein degradation pathway at the INM (mediated by the Asi protein complex) that is distinct from, but complementary to, the ERAD. An unbiased screening of a

Chain‐selective binding of the TAB2‐ and TAB3‐NZFs seems to be related to the hydrophilic Gln that is located in the position of Φ in the TF/Φ motif for ubiquitin binding. The Npl4‐ and Vps36‐NZF domains contain the complete TF/Φ motif (Φ is Met 570 in the Npl4‐NZF or Ile 199 in the Vps36‐NZF) where Phe and Φ form a hydrophobic surface to interact with the Ile 44‐centred hydrophobic patch of ubiquitin. In contrast, Φ is replaced by the hydrophilic Gln 686/709 in TAB2/TAB3 (Supplementary Figure S5A), which contributes little to the distal ubiquitin binding, as mentioned above (Figure 3).. To clarify the relationship between the monoubiquitin binding and Φ in the TF/Φ motif, we mutated Met 570 of the Npl4‐NZF and Ile 199 of the Vps36‐NZF to Gln, and also mutated Gln 686 of the TAB2‐NZF to Ile or Met for GST pull‐down analyses. Strikingly, the Q686M and Q686I mutations enabled the TAB2‐NZF to bind to monoubiquitin and resulted in linkage‐independent binding to ...

Between the 1950s and 1980s, scientists were focusing mostly on how the genetic code was transcribed to RNA and translated to proteins, but how proteins were degraded had remained a neglected research area. With the discovery of the lysosome by Christian de Duve it was assumed that cellular proteins are degraded within this organelle. Yet, several independent lines of experimental evidence strongly suggested that intracellular proteolysis was largely non-lysosomal, but the mechanisms involved have remained obscure. The discovery of the ubiquitin-proteasome system resolved the enigma. We now recognize that degradation of intracellular proteins is involved in regulation of a broad array of cellular processes, such as cell cycle and division, regulation of transcription factors, and assurance of the cellular quality control. Not surprisingly, aberrations in the system have been implicated in the pathogenesis of human disease, such as malignancies and neurodegenerative disorders, which led ...

Selective degradation of proteins in the cell occurs through ubiquitination, which consists of post-translational deposition of ubiquitin on proteins to target them for degradation by proteases. However, ubiquitination does not only impact on protein stability, but promotes changes in their functions. Whereas the deposition of ubiquitin has been amply studied and discussed, the antagonistic activity, deubiquitination, is just emerging and the full model and players involved in this mechanism are far from being completely understood. Nevertheless, it is the dynamic balance between ubiquitination and deubiquitination that is essential for the development and homeostasis of organisms. In this review, we present a detailed analysis of the members of the deubiquitinase (DUB) superfamily in plants and its division in different clades. We describe current knowledge in the molecular and functional characterisation of DUB proteins, focusing primarily on Arabidopsis thaliana. In addition, the striking function of

Intracellular protein degradation is mediated either by lysosomal proteolysis or by a ubiquitin-dependent process that targets unwanted proteins to proteasome. The ubiquitin/proteasome pathway in which many proteins result, is of vital importance for cellular homeostasis and hence for the organism itself. This post-translational modification requires the participation of three types of enzymes, E1 ubiquitin-activating enzyme, E2 conjugating enzyme and E3 ubiquitin ligase. The prominent role of E3 ligases is distinguished by the fact that it bridges the distance between the target protein and ubiquitin and thus mediating in covalent bonding; on the other hand, they are discerned for their high degree of specificity and selectivity concerning their substrates (E2 enzyme, target protein). Arkadia 2C/RNF165 protein belongs to the class of E3 ligases with a distinct zinc ion motif located at the C-terminal region. The RING finger domain is consisted of 41 amino acids and binds two Zn2+ in a unique ...

Ubiquitin-binding protein that specifically recognizes and binds Lys-63-linked ubiquitin. Does not bind Lys-48-linked ubiquitin. Positively regulates the internalization of ligand-activated EGFR by binding to the Ub moiety of ubiquitinated EGFR at the cell membrane ...

Background Ubiquitin is a Nobel Prize winning posttranslational protein modifier. The postranslational modification of proteins with the small protein called ubiquitin is a crucial step in a diverse subset of different cellular regulatory mechanisms. The best described function of ubiquitination is the subsequent degradation of modified proteins by either the 26S proteasome or the vacuole/lysosome. Abberations in these important mechanisms lead to severe diseases ranging from cancer to neurodegeneration. The attachment of ubiquitin to target proteins is therefore a highly regulated process. It is regulated by an enzymatic reaction cascade: First, ubiquitin gets activated and attached to a internal cysteine residue within the ubiquitin acivating enzyme (E1); second the activated ubiquitin is transferred to a internal cysteine of a ubiquitin conjugating enzyme (E2) and finally ubiquitin ligases (E3) allow either the direct transfer of ubiquitin to a lysine residue of a substrate protein (A) or are ...

Many cyanogen bromide cleavage protocols fail to cleave ubiquitin because of its stability in acid. The following protocol has proved effective for cleaving the ubiquitin mutant I36W P37M F45W. ...

A 58-residue-long, PEST-like sequence within the yeast a-factor receptor (Ste3p) specifies the ubiquitination, endocytosis, and consequent vacuolar degradation of the receptor protein (Roth, A. F., Sullivan, D. M., and Davis, N. G. (1998) J. Cell Biol. 142, 949-961). The present work investigates three lysyl residues that map within this sequence as the potential ubiquitin acceptor sites. Lys --> Arg substitution mutants were tested for effects on both ubiquitination and endocytosis. Results indicate that the three lysines function redundantly; a severe blockade to both ubiquitination and endocytosis is seen only for receptors having all three lysines replaced. Of the three, Lys(432) plays the predominant role; ubiquitination and turnover are significantly impaired for receptors having just the K432R mutation. CNBr fragmentation of the receptor protein, used for the physical mapping of the ubiquitin attachment sites, showed PEST-like sequence lysines to be modified both with single ubiquitin ...

After viral infection and the stimulation of some pattern-recognition receptors, TANK-binding kinase I (TBK1) is activated by K63-linked polyubiquitination followed by trans-autophosphorylation. While the activated TBK1 induces type I interferon production by phosphorylating the transcription factor IRF3, the precise molecular mechanisms underlying TBK1 activation remain unclear. We report here the localization of the ubiquitinated and phosphorylated active form of TBK1 to the Golgi apparatus after the stimulation of RIG-I-like receptors (RLRs) or Toll-like receptor-3 (TLR3), due to TBK1 K63-linked ubiquitination on lysine residues 30 and 401. The ubiquitin-binding protein optineurin (OPTN) recruits ubiquitinated TBK1 to the Golgi apparatus, leading to the formation of complexes in which TBK1 is activated by trans-autophosphorylation. Indeed, OPTN deficiency in various cell lines and primary cells impairs TBK1 targeting to the Golgi apparatus and its activation following RLR or TLR3 stimulation.

Ubiquitination-the covalent conjugation of ubiquitin (Ub) to other cellular proteins-regulates a wide range of cellular processes. Often, multiple Ub molecules are added to the substrate to form a Ub chain. Distinct outcomes have been observed for substrates modified with multi-Ub chains linked through particular lysine residues. However, recent studies suggest that Ub chain linkages may not be the key determinant for substrate fate. Here, we review evidence suggesting that Ub-binding proteins play a pivotal role in determining the outcome of substrate ubiquitination. In fulfilling their functions in proteasome-mediated proteolysis or signaling, Ub receptors link ubiquitinated proteins to downstream molecules through protein-protein interactions. Studies of Ub-binding factors may therefore hold the key to understanding the diverse functions of the Ub molecule.. ...

This gene encodes an ubiquitin-like protein (ubiquilin) that shares a high degree of similarity with related products in yeast, rat and frog. Ubiquilins contain an N-terminal ubiquitin-like domain and a C-terminal ubiquitin-associated domain. They physically associate with both proteasomes and ubiquitin ligases, and thus are thought to functionally link the ubiquitination machinery to the proteasome to affect in vivo protein degradation. This ubiquilin has also been shown to modulate accumulation of presenilin proteins, and it is found in lesions associated with Alzheimers and Parkinsons disease. Two transcript variants encoding different isoforms have been found for this gene ...

Gene Information This gene encodes an ubiquitin-like protein (ubiquilin) that shares a high degree of similarity with related products in yeast rat and frog. Ubiquilins contain an N-terminal ubiquitin-like domain and a C-terminal ubiquitin-associated domain. They physically associate with both proteasomes and ubiquitin ligases and thus are thought to functionally link the ubiquitination machinery to the proteasome to affect in vivo protein degradation. This ubiquilin has also been shown to modulate accumulation of presenilin proteins and it is found in lesions associated with Alzheimer's and Parkinson's disease. Two transcript variants encoding different isoforms have been found for this gene. [provided by RefSeq Jul 2008]. ...

The ser-thr Akt plays a crucial role in the regulation of cell success cell growth and proliferation aswell as energy metabolism and it is dysregulated in lots of cancers. of IKKα in managing Akt activity and whether this might involve mTORC2. The tests display that IKKα affiliates with mTORC2 in a number of cancers cells in a way reliant on PI3K/Akt activity which IKKα favorably promotes Akt phosphorylation R935788 at Ser473 with Thr308. Furthermore IKKα enhances mTORC2 kinase activity aimed to Akt on Ser473 and Akt-mediated phosphorylation of FOXO3a and GSK3β however not additional Akt-associated targets such as for example TSC2 and PRAS40 indicating the lifestyle of multiple AFX1 systems of Akt activation in cells. In addition loss of IKKα suppresses growth factor-induced Akt activation associated with mTORC1 inhibition. These results indicate that IKKα serves as a feedforward R935788 regulator of mTORC2 and that IKKα could serve as a key therapeutic target to block mTORC2 and Akt ...

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Abstract: Cellular cross-talk between ubiquitination and other posttranslational modifications contributes to the regulation of numerous processes. One example is ADP-ribosylation of the carboxyl terminus of ubiquitin by the E3 DTX3L/ADP-ribosyltransferase PARP9 heterodimer, but the mechanism remains elusive. Here, we show that independently of PARP9, the conserved carboxyl-terminal RING and DTC (Deltex carboxyl-terminal) domains of DTX3L and other human Deltex proteins (DTX1 to DTX4) catalyze ADP-ribosylation of ubiquitins Gly76. Structural studies reveal a hitherto unknown function of the DTC domain in binding NAD+. Deltex RING domain recruits E2 thioesterified with ubiquitin and juxtaposes it with NAD+ bound to the DTC domain to facilitate ADP-ribosylation of ubiquitin. This ubiquitin modification prevents its activation but is reversed by the linkage nonspecific deubiquitinases. Our study provides mechanistic insights into ADP-ribosylation of ubiquitin by Deltex E3s and will enable future ...

We have shown that in human cells, an antiserum generated against a recombinant UBPY fragment recognizes a protein doublet of Mr 130 000, in good agreement with the predicted UBPY mol. wt of 127 500 Da. The UBPY bands were enhanced upon transfection of a sense UBPY cDNA and, most importantly, were lowered in abundance upon transfection of an antisense cDNA construct. UBPY was able to remove ubiquitin from ubiquitin adducts. Its expression was undetectable upon serum starvation of normal human fibroblasts, and the protein reappeared upon re‐stimulation, in mid G1 coincident with the accumulation of cyclin D1. UBPY levels were reduced in non‐immortalized cells as they reached confluence and arrested in G0, while they remained high and even increased in transformed cells.. To date, no other studies have demonstrated the effects of down‐regulating a UBP in mammalian cells. We have been able to inhibit UBPY accumulation using an antisense cDNA vector and could demonstrate that G0‐arrested ...

The HaloTag® fusion vectors are designed to be used as the fluorescent acceptor in NanoBRET™ assays that monitor interactions of a specific target protein along the UPS pathway.

Accepts ubiquitin from the E1 complex and catalyzes its covalent attachment to other proteins. In vitro catalyzes Lys-48-linked polyubiquitination. Mediates the selective degradation of short-lived and abnormal proteins. Functions in the E6/E6-AP-induced ubiquitination of p53/TP53. Mediates ubiquitination of PEX5 and auto-ubiquitination of STUB1, TRAF6 and TRIM63/MURF1. Ubiquitinates STUB1-associated HSP90AB1 in vitro. Lacks inherent specificity for any particular lysine residue of ubiquitin. Essential for viral activation of IRF3. Mediates polyubiquitination of CYP3A4.

634 The ubiquitin-proteasome pathway plays a major role in cancer development and is a bona fide target for cancer therapy. The covalent attachment of ubiquitin to a target protein proceeds through a multi-enzyme cascade. Initially, E1 activates ubiquitin and is then transferred to a cysteine residue of an E2 ubiquitin-conjugating enzyme (ubc). Finally, the E2 itself, or more commonly in concert with an E3 ubiquitin ligase, ligates the ubiquitin via its carboxy terminus to lysine residues of a protein substrate. This enzymatic cascade, responsible for ubiquitylating target proteins is complex, and its regulation is only beginning to be understood. The complexity stems from the large number of E2 and E3 enzymes; in humans, more than 30 E2s and hundreds of putative E3 ligases have been identified. The enzymatic nature, multitude of E2 and E3s and their specific substrate recognition predestines them as therapeutic targets in major diseases.. Targeting components of ubiquitination pathway for drug ...

PD Dr. Thorsten Pfirrmann. I studied Technical Biology from 1995 to 2002 at the University of Stuttgart, Germany, which spawned my keen and longterm interest in the ubiquitin proteasome system. I carried out my Masters (Diploma) work examining the Saccharomyces cerevisiae specific deubiquitinating enzyme Ubp6 in the laboratory of Rohan Baker at the John Curtin School of Medical Research, Canberra, Australia. In 2002, I returned to Stuttgart to join the laboratory of Dieter Wolf, where as a Ph.D. student I discovered a novel conserved E3 ubiquitin ligase complex and experimentally addressed certain aspects of the deubiquitinating enzyme Ubp14. In 2006, I moved to Stockholm, Sweden for postdoctoral studies, and first worked on the function of the Ubiquitin C-terminal hydrolase UCH-L1 in the laboratory of Maria Masucci at Karolinska Institute. In 2008, I joined the laboratory of Per O. Ljungdahl at Stockholm University, where I focused on the ubiquitin proteasome dependent activation mechanism of ...

The ubiquitin E1, E2, and E3 ligase enzymes are the enzymatic core of the ubiquitination pathway. The E2-E3 complex interacts with the substrate, catalyzing ubiquitin addition to the substrate. Thus, the expression, activity, localization, and selectivity of ubiquitin E2s and E3s are important parameters that can serve to regulate ubiquitination. The E2-E3 combination used in the ubiquitination reaction can also influence the fate of the substrate through determining the extent and nature of ubiquitin addition. The majority of substrates observed to date are modified by the attachment of a Lys-48-linked ubiquitin chain, which targets the substrate for degradation by the 26S proteasome. Substrates modified with other types of polyubiquitin chains linked via ubiquitin Lys-6, -11, -29, and -63, or modified with a single ubiquitin, face different or unknown fates. For example, the heterodimeric E2 UBC13/methyl methane sulfonate sensitivity 2 functions with the RING E3 TNF receptor-associated factor ...

The androgen receptor (AR) is a transcription factor belonging to the family of nuclear receptors which mediates the action of androgens in the development of urogenital structures. AR expression is regulated post-translationally by the ubiquitin/proteasome system. This regulation involves more complex mechanisms than typical degradation. The ubiquitin/proteasome system may regulate AR via mechanisms that do not engage in receptor turnover. Given the critical role of AR in sexual development, this complex regulation is especially important. Deregulation of AR signalling may be a causal factor in prostate cancer development. AR is the main target in prostate cancer therapies. Due to the critical role of the ubiquitin/proteasome system in AR regulation, current research suggests that targeting AR degradation is a promising approach.

Transcriptional repression of ubiquitin B (UBB) is a cancer-subtype-specific alteration that occurs in a substantial population of patients with cancers of the female reproductive tract. UBB is 1 of 2 genes encoding for ubiquitin as a polyprotein consisting of multiple copies of ubiquitin monomers. Silencing of UBB reduces cellular UBB levels and results in an exquisite dependence on ubiquitin C (UBC), the second polyubiquitin gene. UBB is repressed in approximately 30% of high-grade serous ovarian cancer (HGSOC) patients and is a recurrent lesion in uterine carcinosarcoma and endometrial carcinoma. We identified ovarian tumor cell lines that retain UBB in a repressed state, used these cell lines to establish orthotopic ovarian tumors, and found that inducible expression of a UBC-targeting shRNA led to tumor regression, and substantial long-term survival benefit. Thus, we describe a recurrent cancer-specific lesion at the level of ubiquitin production. Moreover, these observations reveal the ...

Polyamines are essential organic polycations which have been implicated in various cellular processes. Cellular polyamine concentrations are regulated mainly at the level of synthesis but also at the level of catabolism and export. Elevated cellular polyamine levels lead to the induction of antizyme translation by a highly conserved mechanism involving +1 ribosomal frameshifting. The antizyme targets ornithine decarboxylase (ODC), the rate limiting enzyme in polyamine biosynthesis for ubiquitin-independent degradation by the 26S proteasome. The N-terminal degron of ODC and the antizyme are essential for the effective degradation of ODC. Polyamines also regulate antizyme levels by blocking its ubiquitin-dependent protein degradation. In this study, the mechanisms of regulating polyamine levels by the antizyme are dissected ...

Author Summary Autophagy is an evolutionarily conserved process that sequestrates and delivers cytoplasmic macromolecules and organelles to the vacuoles or lysosomes for degradation. In plants, autophagy is involved in supplying internal nutrients during starvation and in promoting cell survival during senescence and during biotic and abiotic stresses. Arabidopsis NBR1 is a homolog of mammalian autophagy cargo adaptors P62 and NBR1. Disruption of Arabidopsis NBR1 caused increased sensitivity to a spectrum of abiotic stresses but had no significant effect on plant senescence, responses to carbon starvation, or resistance to a necrotrophic pathogen. NBR1 contains an ubiquitin-binding domain, and the compromised stress tolerance of autophagy mutants was associated with increased accumulation of NBR1 and ubiquitin-positive cellular protein aggregates in the insoluble protein fraction under stress conditions. Based on these results, we propose that NBR1 targets ubiquitinated protein aggregates most likely

Ubiquitin carboxy-terminal hydrolase L1 (UCHL1) is a deubiquitylating enzyme that is proposed as a potential therapeutic target in neurodegeneration, cancer, and liver and lung fibrosis. Herein we report the discovery of the most potent and selective UCHL1 probe (IMP-1710) to date based on a covalent inhibitor scaffold and apply this probe to identify and quantify target proteins in intact human cells. IMP-1710 stereoselectively labels the catalytic cysteine of UCHL1 at low nanomolar concentration in cells. We further demonstrate that potent and selective UCHL1 inhibitors block pro-fibrotic responses in a cellular model of idiopathic pulmonary fibrosis, supporting the potential of UCHL1 as a potential therapeutic target in fibrotic diseases.

A single protein comprised of tandem repeats of the UBIQUITIN 78-amino acid sequence. It is a product of the polyubiquitin gene which contains multiple copies of the ubiquitin coding sequence. Proteolytic processing of ubiquitin C results in the formation of individual ubiquitin molecules. This protein is distinct from POLYUBIQUITIN, which is a protein formed through isopeptide linkage of multiple ubiquitin species ...

Looking for online definition of ubiquitin thiolesterase 29 in the Medical Dictionary? ubiquitin thiolesterase 29 explanation free. What is ubiquitin thiolesterase 29? Meaning of ubiquitin thiolesterase 29 medical term. What does ubiquitin thiolesterase 29 mean?

|jats:title|Abstract|/jats:title| |jats:p|OTULIN (OTU Deubiquitinase With Linear Linkage Specificity) specifically hydrolyzes methionine1 (Met1)-linked ubiquitin chains conjugated by LUBAC (linear ubiquitin chain assembly complex). Here we report on the mass spectrometric identification of the OTULIN interactor SNX27 (sorting nexin 27), an adaptor of the endosomal retromer complex responsible for protein recycling to the cell surface. The C-terminal PDZ-binding motif (PDZbm) in OTULIN associates with the cargo-binding site in the PDZ domain of SNX27. By solving the structure of the OTU domain in complex with the PDZ domain, we demonstrate that a second interface contributes to the selective, high affinity interaction of OTULIN and SNX27. SNX27 does not affect OTULIN catalytic activity, OTULIN-LUBAC binding or Met1-linked ubiquitin chain homeostasis. However, via association, OTULIN antagonizes SNX27-dependent cargo loading, binding of SNX27 to the VPS26A-retromer subunit and endosome-to

Study of the mechanisms underlying breast and ovarian cancer development and progression. Dr. Bazzaros laboratory is interested in studying abnormalities of protein degradation pathways in breast and ovarian cancer. The Ubiquitin-Proteasome-System (UPS) is responsible for degradation of over 90% of short-lived intracellular proteins. Protein degradation through Ubiquitin-Proteasome-System is a multistep process that begins with de-ubiquitination of ubiquitin-tagged target molecules by de-ubiquitinating enzymes following their entrance in the 20S catalytic chamber of the proteasomes were the actual degradation occurs. The polypeptide targets of the proteasome include proteins involved in cell cycle progression, survival and inflammation and while the ubiquitin-dependent proteasomal degradation is crucial for both normal and malignant cells the higher demand for metabolic/catabolic activity associated with the malignant phenotype renders the ubiquitin-proteasome pathway a suitable tool for cancer ...

Schizophrenia or schizoaffective disorders are often found in patients affected by DiGeorge/velo-cardio-facial syndrome (DGS/VCFS) as a result of hemizygosity of chromosome 22q11.2. We evaluated the UFD1L gene, mapping within the DGS/VCFS region, as a potential candidate for schizophrenia susceptibility. UFD1L encodes for the ubiquitin fusion degradation 1 protein, which is expressed in the medial telencephalon during mouse development. Using case control, simplex families (trios), and functional studies, we provided evidence for association between schizophrenia and a single nucleotide functional polymorphism, -277A/G, located within the noncoding region upstream the first exon of the UFD1L gene. The results are supportive of UFD1L involvement in the neurodevelopmental origin of schizophrenia and contribute in delineating etiological and pathogenetic mechanism of the schizophrenia subtype related to 22q11.2 deletion syndrome. ...

E3 ubiquitin ligases catalyze ubiquitination, which can target specific proteins for degradation. Although a growing number of E3 ubiquitin ligases and their targets have been identified, much less is known about the mechanisms that regulate their activity. A convergence of data indicate that phosphorylation regulates the binding of Nedd4-2, a HECT (homologous to the E6-AP C terminus) domain E3 ubiquitin ligase, to its target, the epithelial Na+ channel ENaC. Nedd4-2 phosphorylation is emerging as a central convergence point for the regulation of epithelial Na+ transport.. ...

TY - JOUR. T1 - Post-translational regulation of FLC is mediated by an E3 ubiquitin ligase activity of SINAT5 in Arabidopsis. AU - Park, Bong Soo. AU - Sang, Wan Gyu. AU - Yeu, Song Yion. AU - Choi, Yang Do. AU - Paek, Nam Chon. AU - Kim, Min Chul. AU - Song, Jong Tae. AU - Seo, Hak Soo. PY - 2007/8/1. Y1 - 2007/8/1. N2 - Suppression of Flowering Locus C (FLC) is critical for the transition from the vegetative to reproductive phase in Arabidopsis. FLC represses the expression of several genes involved in floral induction and its transcription is positively or negatively regulated by FRIGIDA or by vernalization, respectively. However, the regulatory mechanisms for the level and stability of FLC protein throughout development are unknown. Here, we show that SINAT5 colocalizes with FLC in the nuclear bodies and that its zinc finger motif interacts directly with the MADS-box domain of FLC. In addition, it is shown that SINAT5 has an E3 ubiquitin ligase activity towards FLC as a substrate, suggesting ...

Polycomb group proteins Bmi-1 and Ring1B are core subunits of the PRC1 complex, which plays important roles in the regulation of Hox gene expression, X-chromosome inactivation, tumorigenesis, and stem cell self-renewal. The RING finger protein Ring1B is an E3 ligase that participates in the ubiquitination of lysine 119 of histone H2A, and the binding of Bmi-1 stimulates the E3 ligase activity. We have mapped the regions of Bmi-1 and Ring1B required for efficient ubiquitin transfer and determined a 2.5-A structure of the Bmi-1-Ring1B core domain complex. The structure reveals that Ring1B hugs Bmi-1 through extensive RING domain contacts and its N-terminal tail wraps around Bmi-1. The two regions of interaction have a synergistic effect on the E3 ligase activity. Our analyses suggest a model where the Bmi-1-Ring1B complex stabilizes the interaction between the E2 enzyme and the nucleosomal substrate to allow efficient ubiquitin transfer.. ...

Proteins degraded by the ubiquitin-mediated proteolysis must be covalently linked to the small protein ubiquitin. Ubiquitin serves as a molecular tag that marks proteins for degradation by the 26S proteasome. The selection of substrates for ubiquitination is prescribed by a specific class of enzymes called ubiquitin-protein ligases (also known as E3s). Most E3 ligases comprise a large superfamily of protein-protein complexes. They bind the substrate protein and a cognate ubiquitin-conjugating enzyme (E2), and catalyze the transfer of ubiquitin from the E2 to specific lysine residues within the substrate. Thus E3s are responsible for both ubiquitin transfer and specific recognition of each of the target proteins. However, the molecular details underlying these two processes remain poorly understood. ...

p,Ubiquitin-mediated protein degradation is a common feature in diverse plant cell signaling pathways; however, the factors that control the dynamics of regulated protein turnover are largely unknown. One of the best-characterized families of E3 ubiquitin ligases facilitates ubiquitination of auxin (aux)/indole-3-acetic acid (IAA) repressor proteins in the presence of auxin. Rates of auxin-induced degradation vary widely within the Aux/IAA family, and sequences outside of the characterized degron (the minimum region required for auxin-induced degradation) can accelerate or decelerate degradation. We have used synthetic auxin degradation assays in yeast (Saccharomyces cerevisiae) and in plants to characterize motifs flanking the degron that contribute to tuning the dynamics of Aux/IAA degradation. The presence of these rate motifs is conserved in phylogenetically distant members of the Arabidopsis (Arabidopsis thaliana) Aux/IAA family, as well as in their putative Brassica rapa orthologs. We ...

ASFUM1_6.PE123 Location/Qualifiers FT CDS join(443140..444793,444856..444917) FT /codon_start=1 FT /gene_family=HOG000202292 [ FAMILY / ALN / TREE ] FT /evidence=3: Inferred from homology FT /gene_id=IGI18207414 FT /orf_name=AFUA_6G02380 FT /product=Ubiquitin C-terminal hydrolase, putative FT /EC_number=3.1.2.15 FT /function=ubiquitin thiolesterase activity FT /biological_process=ubiquitin-dependent protein catabolic FT process FT /protein_id=EAL85801.1 FT /db_xref=GO:0004221 FT /db_xref=GO:0006511 FT /db_xref=HOGENOM:HBG027359 FT /db_xref=HOGENOM:HBG524155 FT /db_xref=InterPro:IPR000626 FT /db_xref=InterPro:IPR001394 FT /db_xref=InterPro:IPR018200 FT /db_xref=InterPro:IPR019955 FT /db_xref=UniParc:UPI000051E826 FT /db_xref=UniProtKB/TrEMBL:Q4WCT7 FT /transl_table=1 FT /translation=MFSVIVKHQGKRHEVELDPSANGETLKYQMYSLTGVEPERQKILV FT KGGQLKDETPLSALNAKPGQTFMMMGTPSGGQDAVDLGRPKEPVKFLEDMTEAEAARAE FT GAIPAGLQNLGNTCYLNSTLQTLRSVPELQQELLNYKPSAGSSAGSRLSDLSSLGLGGL FT ...

1. ShaidS, BrandtsCH, ServeH, DikicI (2013) Ubiquitination and selective autophagy. Cell Death Differ 20: 21-30.. 2. LyzengaWJ, StoneSL (2012) Abiotic stress tolerance mediated by protein ubiquitination. J Exp Bot 63: 599-616.. 3. ChristensenAH, SharrockRA, QuailPH (1992) Maize polyubiquitin genes: structure, thermal perturbation of expression and transcript splicing, and promoter activity following transfer to protoplasts by electroporation. Plant Mol Biol 18: 675-689.. 4. GenschikP, ParmentierY, DurrA, MarbachJ, CriquiMC, et al. (1992) Ubiquitin genes are differentially regulated in protoplast-derived cultures of Nicotiana sylvestris and in response to various stresses. Plant Mol Biol 20: 897-910.. 5. SunCW, CallisJ (1997) Independent modulation of Arabidopsis thaliana polyubiquitin mRNAs in different organs and in response to environmental changes. Plant J 11: 1017-1027.. 6. GuoQF, ZhangJ, GaoQ, XingSC, LiF, et al. (2008) Drought tolerance through overexpression of monoubiquitin in transgenic ...

Evidence suggests that regulated ubiquitination of proteins plays a critical role in the development and plasticity of the central nervous system. We have previously identified the ubiquitin ligase Praja1 as a gene product induced during fear memory consolidation. However, the neuronal function of this enzyme still needs to be clarified. Here, we investigate its involvement in the nerve growth factor (NGF)-induced differentiation of rat pheochromocytoma (PC12) cells. Praja1 co-localizes with cytoskeleton components and the neurotrophin receptor interacting MAGE homologue (NRAGE). We observed an enhanced expression of Praja1 after 3 days of NGF treatment and a suppression of neurite formation upon Praja1 overexpression in stably transfected PC12 cell lines, which was associated with a proteasome-dependent reduction of NRAGE levels. Our data suggest that Praja1, through ubiquitination and degradation of NRAGE, inhibits neuronal differentiation. The two murine isoforms, Praja1.1 and Praja1.2, appear to be

Chronic myelogenous leukemia (CML) is a malignant hematopoietic stem cell disorder that is invariably associated with the expression of the p210 Bcr-Abl fusion protein. Although the deregulated, Abl-encoded tyrosine kinase activity is essential for disease progression, several studies have shown that Bcr encoded sequences are also necessary for p210 Bcr-Abl-mediated leukemogenesis. We have identified a non-classical ubiquitin binding domain (UBD) within the NH2-terminal Bcr sequences of p210 Bcr-Abl. Deletion of the UBD (p210 Bcr-Abl(ΔUBD)) does not impair the auto-or trans-kinase activity of p210 Bcr-Abl, nor does it impair the ability of p210 Bcr-Abl to interact with Grb2 and activate Erk1/2 signaling. Although β-catenin has been previously identified as a binding partner for Bcr and Bcr-Abl, p210 Bcr-Abl(ΔUBD) does not interact with β-catenin. Treatment with an E1 inhibitor impairs the interaction between β-catenin and p210 Bcr-Abl, suggesting that the interaction is ubiquitin-dependent. ...

Inhibition of HIV-1 by A3G that escapes Vif mediated degradation. In an HIV-1 producer cell, the HIV-1 virus infectivity factor (Vif) interacts with the cotranscription factor CBF-β and a cellular ubiquitin ligase complex to become the substrate recognition subunit of an E3 ubiquitin ligase. (1) The Vif-E3 complex recruits an E2 enzyme that transfers ubiquitin molecules to A3G, thereby signaling it for degradation through the proteasome pathway. (2) A3G that escapes this fate, either fortuitously or in the presence of a Vif-defective HIV-1 strain, can enter an assembling virus particle through interactions with RNA (host 7SL RNA or HIV-1 genomic RNA) and the nucleocapsid portion of Gag. Then, A3G travels with the HIV-1 particle to a target cell where it waits for reverse transcription of the HIV-1 genomic RNA to (-)DNA to ensue. A3G, a single-stranded DNA deaminase is able to deaminate cytosine (C) to uracil (U) in (-)DNA, which causes the reverse transcriptase to introduce guanine (G) to ...

The present study demonstrates that ritonavir, by inhibiting the chymotrypsin-like activity of the proteasome, has cytostatic and cytotoxic effects on glioma cells that can however induce resistances in vitro and are unable to control tumor proliferation in vivo.. The idea that ubiquitin/proteasome pathway is an attractive target for novel anticancer therapies is actively explored (24, 46). Indeed tumor cells, including glioma cells, not only progress through up-regulation of oncogenes, but also through increase of proteolytic degradation of tumor suppressors and cell cycle inhibitors, which mostly requires the ubiquitin/proteasome system (20, 22, 47). The constitutively high proteasome basal activity and the presence of many ubiquitinylated proteins, as observed here in GL15 cells, suggests that protein degradation occurs through increase of both protein targeting and endopeptidase activity.. A commonly used proteasome inhibitor, lactacystin, inhibits the proteasome by binding covalently to the ...

Author: Liwocha, Joanna et al.; Genre: Journal Article; Published in Print: 2020; Keywords: Enzyme mechanisms; Enzymes; Protein design|br/|; Title: Linkage-specific ubiquitin chain formation depends on a lysine hydrocarbon ruler

1. WelchmanRLGordonCMayerRJ 2005 Ubiquitin and ubiquitin-like proteins as multifunctional signals. Nat Rev Mol Cell Biol 6 599 609. 2. HickeLSchubertHLHillCP 2005 Ubiquitin-binding domains. Nat Rev Mol Cell Biol 6 610 621. 3. ChenZJSunLJ 2009 Nonproteolytic functions of ubiquitin in cell signaling. Mol Cell 33 275 286. 4. MukhopadhyayDRiezmanH 2007 Proteasome-independent functions of ubiquitin in endocytosis and signaling. Science 315 201 205. 5. LeeTVDingTChenZRajendranVScherrH 2008 The E1 ubiquitin-activating enzyme Uba1 in Drosophila controls apoptosis autonomously and tissue growth non-autonomously. Development 135 43 52. 6. DegterevAYuanJ 2008 Expansion and evolution of cell death programmes. Nat Rev Mol Cell Biol 9 378 390. 7. KumarS 2007 Caspase function in programmed cell death. Cell Death Differ 14 32 43. 8. BaoQShiY 2007 Apoptosome: a platform for the activation of initiator caspases. Cell Death Differ 14 56 65. 9. RiedlSJSalvesenGS 2007 The apoptosome: signalling platform of cell ...

p53 is a tumor suppressor that is widely mutated or deleted in cancer cells. Mdm2, an E3 ubiquitin ligase, is the master regulator of p53. It targets p53 for proteasomal degradation, restraining the potent activity of p53 and enabling cell survival and proliferation. There are complex regulatory mechanisms balancing the activity and stability of Mdm2 in a cell. Mdm2 has an extremely short half-life in the unstressed cell and its regulation is not well understood. Like most E3 ligases, Mdm2 can autoubiquitinate. Previously, the sole function of autoubiquitination was thought to be to signal Mdm2 degradation. Here I show that autoubiquitination of Mdm2 is an activating event. Mdm2 that has been conjugated with polyubiquitin chains exhibits substantially enhanced activity to polyubiquitinate p53. Mechanistically, autoubiquitination of Mdm2 facilitates the recruitment of the E2 ubiquitin-conjugating enzymes through non-covalent interactions between the ubiquitin chains on Mdm2 and the ubiquitin-binding

UBR5 (ubiquitin protein ligase E3 component n-recognin 5), Authors: Dessen P. Published in: Atlas Genet Cytogenet Oncol Haematol.

Protein degradation via the ubiquitin proteasome system (UPS) is one of the cells tools for selective negative regulation of intracellular proteins. Degradation via the UPS has roles in maintaining protein quality control, signaling, and cell cycle progression [1, 2]. Ubiquitin is a small protein that is highly conserved in eukaryotes and is the crux of the UPS system. The UPS system is built upon three classes of enzymes--E1, E2 and E3- that act sequentially to build ubiquitin chains on protein substrates. Once a protein substrate has been modified by a chain of at least four ubiquitins, it is then degraded by the 26S proteasome in an ATP-dependent manner [3, 4].. The proteasome is a 33-subunit protein complex that is involved in turning over a minimum of 20% of the yeast proteome (SCUD; http://scud.kaist.ac.kr/index.html). Other lines of evidence suggest that the vast majority of cytoplasmic protein degradation is mediated by the proteasome [5]. The proteasome is composed of two main ...

The Ubiquitin Interacting Motif (UIM), or LALAL-motif, is a stretch of about 20 amino acid residues, which was first described in the 26S proteasome subunit PSD4/RPN-10 that is known to recognise ubiquitin [(PUBMED:9488668),(PUBMED:11406394)]. In addition, the UIM is found, often in tandem or triplet arrays, in a variety of proteins either involved in ubiquitination and ubiquitin metabolism, or known to interact with ubiquitin-like modifiers. Among the UIM proteins are two different subgroups of the UBP (ubiquitin carboxy-terminal hydrolase) family of deubiquitinating enzymes, one F-box protein, one family of HECT-containing ubiquitin-ligases (E3s) from plants, and several proteins containing ubiquitin-associated UBA and/or UBX domains [(PUBMED:12062168)]. In most of these proteins, the UIM occurs in multiple copies and in association with other domains such as UBA (IPR015940), UBX (IPR001012), ENTH, EH (IPR000261), VHS (IPR002014), SH3 (IPR001452), HECT (IPR000569), VWFA (IPR002035), EF-hand ...

Defects in SLX4, a scaffold for DNA repair nucleases, result in Fanconi anemia (FA), due to the defective repair of inter-strand DNA crosslinks (ICLs). Some FA patients have an SLX4 deletion removing two tandem UBZ4-type ubiquitin-binding domains that are implicated in protein recruitment to sites of DNA damage. Here, we show that human SLX4 is recruited to sites of ICL induction but that the UBZ-deleted form of SLX4 in cells from FA patients is not. SLX4 recruitment does not require either the ubiquitylation of FANCD2 or the E3 ligases RNF8, RAD18 and BRCA1. We show that the first (UBZ-1) but not the second UBZ domain of SLX4 binds to ubiquitin polymers, with a preference for K63-linked chains. Furthermore, UBZ-1 is required for SLX4 recruitment to ICL sites and for efficient ICL repair in murine fibroblasts. The SLX4 UBZ-2 domain does not bind to ubiquitin in vitro or contribute to ICL repair, but it is required for the resolution of Holliday junctions in vivo. These data shed light on SLX4 ...

Power and Promise of Ubiquitin Carboxyl-terminal Hydrolase 37 as a Target of Cancer Therapy UCH37;deubiquitination;proteasome;protein interaction;tumor therapy target; Ubiquitin carboxyl-terminal hydrolase 37 (UCH37, also called UCHL5), a member of the deubiquitinating enzymes, can suppress protein degradation through disassembling polyubiquitin from the distal subunit of the chain. It has been proved that UCH37 can be activated by proteasome ubiqutin chain receptor Rpn13 and incorporation into the 19S complex. UCH37, which has been reported to assist in the mental development of mice, may play an important role in oncogenesis, tumor invasion and migration. Further studies will allow a better understanding of roles in cell physiology and pathology, embryonic development and tumor formation, hopefully providing support for the idea that UCH37 may constitute a new interesting target for the development of anticancer drugs.

Power and Promise of Ubiquitin Carboxyl-terminal Hydrolase 37 as a Target of Cancer Therapy UCH37;deubiquitination;proteasome;protein interaction;tumor therapy target; Ubiquitin carboxyl-terminal hydrolase 37 (UCH37, also called UCHL5), a member of the deubiquitinating enzymes, can suppress protein degradation through disassembling polyubiquitin from the distal subunit of the chain. It has been proved that UCH37 can be activated by proteasome ubiqutin chain receptor Rpn13 and incorporation into the 19S complex. UCH37, which has been reported to assist in the mental development of mice, may play an important role in oncogenesis, tumor invasion and migration. Further studies will allow a better understanding of roles in cell physiology and pathology, embryonic development and tumor formation, hopefully providing support for the idea that UCH37 may constitute a new interesting target for the development of anticancer drugs.

Ubiquitination of the chemokine receptor CXCR4 serves as a targeting signal for lysosomal degradation, but the mechanisms mediating ubiquitination and lysosomal sorting remain poorly understood. Here we report that the Nedd4-like E3 ubiquitin ligase AIP4 mediates ubiquitination of CXCR4 at the plasm …

The ubiquitin-proteasome pathway is one of the most important proteolytic pathways in eukaryotes. In this pathway, the small protein ubiquitin is attached to protein substrates, and the ubiquitin-protein conjugates are recognized and degraded by the 26S proteasome (Fang and Weissman, 2004). The SCF complexes are a major class of ubiquitin ligase enzyme (Gagne et al., 2002; Petroski and Deshaies, 2005). In this complex, the F-box protein plays a critical role in the determination of substrate specificity (Petroski and Deshaies, 2005). The plant hormone auxin directly induces rapid degradation of the Aux/IAA family of transcriptional repressors by SCFTIR1/AFB E3 ubiquitin ligase (Gray et al., 2001; Dharmasiri et al., 2005a, 2005b; Kepinski and Leyser, 2005; Tan et al., 2007). In Arabidopsis, TIR1 is a member of a small group of F-box proteins that also includes AFB1 through AFB5 and the jasmonic acid receptor CORONATINE INSENSITIVE1 (COI1; Dharmasiri et al., 2005b). The TIR1 protein plays a ...

Prokaryotes form ubiquitin (Ub)-like isopeptide bonds on the lysine residues of proteins by at least two distinct pathways that are reversible and regulated. (TtuB tRNA-two-thiouridine B) that differ from Ub in amino acid sequence yet share a common β-grasp fold also form isopeptide bonds by a mechanism that appears streamlined compared with ubiquitylation. SAMPs and TtuB are found to be members of a small group of Ub-fold proteins that function not only in protein modification but also in sulfur-transfer pathways associated with tRNA thiolation and molybdopterin biosynthesis. These multifunctional Ub-fold proteins are thought to be some of the most ancient of Ub-like protein modifiers. TtuB (tRNA-two-thiouridine B) which differ from Ub in sequence but share a common compact globular β-grasp fold (27 77 These Ub-fold proteins are linked by Gimatecan isopeptide bonds to lysine residues of protein targets by mechanisms that appear to be simple versions of ubiquitylation in their requirement for ...

Lenalidomide promotes p53 degradation by inhibiting MDM2 auto-ubiquitination in myelodysplastic syndrome with chromosome 5q deletion. Oncogene. 2013 Feb 28; 32(9):1110-20 ...

Following DNA double-strand breaks (DSB), multiple proteins are recruited to chromatin in a sequential manner to mediate various aspects of the DNA damage response. 53BP1 is a chromatin-binding protein that is recruited to DSBs to promote DNA repair by nonhomologous end joining. 53BP1 binding to chromatin is mediated by its tandem Tudor domain, which recognizes dimethylated histone H4 lysine 20 (H4K20me2). However, because 53BP1 recruitment to DSBs also requires the E3 ubiquitin ligase RNF168, exactly how ubiquitin promotes the accumulation of a methyl-histone binding protein at break sites remains a mystery. To better understand the ubiquitin-dependent mechanism of 53BP1 recruitment to DSBs, Fradet-Turcotte and colleagues turned to the Schizosaccharomyces pombe 53BP1 ortholog, Crb2. Like human 53BP1, Crb2 has a tandem Tudor domain that binds H4K20me2, but fission yeast do not have a RNF168 homolog, and Crb2 does not form DNA damage-induced foci when expressed in human cells. Mapping of the ...

Following DNA double-strand breaks (DSB), multiple proteins are recruited to chromatin in a sequential manner to mediate various aspects of the DNA damage response. 53BP1 is a chromatin-binding protein that is recruited to DSBs to promote DNA repair by nonhomologous end joining. 53BP1 binding to chromatin is mediated by its tandem Tudor domain, which recognizes dimethylated histone H4 lysine 20 (H4K20me2). However, because 53BP1 recruitment to DSBs also requires the E3 ubiquitin ligase RNF168, exactly how ubiquitin promotes the accumulation of a methyl-histone binding protein at break sites remains a mystery. To better understand the ubiquitin-dependent mechanism of 53BP1 recruitment to DSBs, Fradet-Turcotte and colleagues turned to the Schizosaccharomyces pombe 53BP1 ortholog, Crb2. Like human 53BP1, Crb2 has a tandem Tudor domain that binds H4K20me2, but fission yeast do not have a RNF168 homolog, and Crb2 does not form DNA damage-induced foci when expressed in human cells. Mapping of the ...

A second member of the E3 ubiquitin ligases, Fbxo7, is also mutated in early-onset Parkisonism [91-97]. In contrast with Parkin, which functions as a single-polypeptide E3 ligase, Fbxo7 is a component of a multisubunit E3 ligase of the Cullin-RING ligase family (CRL). CRLs are a large class of multisubunit E3 ubiquitin ligases that feature a scaffolding protein, termed a cullin, and associate with a RING-box protein (reviewed in refs [98,99]). The archetypal CRL is the SCF-type ligase family, which comprises Cullin1, Skp1, the RING protein Rbx1, and an F-box. Skp1 associates with substrate adaptor proteins that contain F-boxes (Skp1-Cullin1-Fbox), which recruits substrates to the CRL for ubiquitylation.. Until recently, Fbxo7 had only four identified substrates. The first of these is HURP (hepatoma up-regulated protein) [100]. HURP is found at high levels in hepatocellular carcinomas and is required during mitotic spindle assembly for correct alignment of chromosomes [101]. As such, it is ...

Parkin is encoded by the PARK2 gene in humans; its precise function is unknown. However, it is known to be part of a multiprotein E3 ubiquitin ligase complex, catalyzing the covalent attachment of ubiquitin moieties onto substrate proteins. The ubiquitin-tagged proteins are then degraded by ubiquitin-proteasome complexes. Mutations in the PARK2 gene are associated with familial and autosomal recessive juvenile forms of Parkinson disease. It has been suggested that loss of function of the parkin protein leads to dopaminergic cell death, but the mechanism is not clear. Parkin is also known as Parkinson protein 2, E3 ubiquitin protein ligase; Parkinson disease (autosomal recessive, juvenile) 2, parkin; E3 ubiquitin-protein ligase parkin, Parkinson disease protein 2, PDJ, PRKN, AR-JP, and LPRS2.. ...

Parkin is encoded by the PARK2 gene in humans; its precise function is unknown. However, it is known to be part of a multiprotein E3 ubiquitin ligase complex, catalyzing the covalent attachment of ubiquitin moieties onto substrate proteins. The ubiquitin-tagged proteins are then degraded by ubiquitin-proteasome complexes. Mutations in the PARK2 gene are associated with familial and autosomal recessive juvenile forms of Parkinson disease. It has been suggested that loss of function of the parkin protein leads to dopaminergic cell death, but the mechanism is not clear. Parkin is also known as Parkinson protein 2, E3 ubiquitin protein ligase; Parkinson disease (autosomal recessive, juvenile) 2, parkin; E3 ubiquitin-protein ligase parkin, Parkinson disease protein 2, PDJ, PRKN, AR-JP, and LPRS2.. ...