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Proteasome subunit alpha type-5 (PSMA5) is a member of the peptidase T1A family. The proteasome is a multicatalytic proteinase complex which is distinguished by its ability to cleave peptides with Arg, Phe, Tyr, Leu, and Glu adjacent to the leaving group at neutral or slightly basic pH. Proteasomes are spread throughout eukaryotic cells at a high concentration and cleave peptides in an ATP/ubiquitin-dependent process in a non-lysosomal pathway. PSMA5 interacts with PLK1. The PSMA5 peptidase has a very wide-ranging specificity for cleavage of peptide bonds.

Proteasome subunit beta type-9 (PSMB9) belongs to the proteasome B-type family which is a 20S core beta subunit. PSMB9 is positioned in the class II region of the MHC (major histocompatibility complex). Expression of the PSMB9 protein is induced by INFG and this gene product replaces catalytic subunit 1 (proteasome beta 6 subunit) in the immunoproteasome.

PSMB1 is part of the proteasome B-type family, also identified as the T1B family, that is a 20S core beta subunit. PSMB1 is tightly linked to the TBP (TATA-binding protein) gene in human and in mouse, and is transcribed in the opposite orientation in both species.The main function of PSMB1 is its degradation activity of unnecessary or damaged proteins by proteolysis. PSMB1 is a multicatalytic proteinase complex which is characterized by its ability to cleave peptides with arg, phe, tyr, leu, and glu adjacent to the leaving group at neutral or slightly basic ph. the proteasome has an atp-dependent proteolytic activity.

Proteasome subunit beta type-7 (PSMB7) belongs to the proteasome B-type family. PSMB7 is a multicatalytic proteinase complex with an extremely ordered ring-shaped 20S core structure. This core structure is comprised of 4 rings of 28 non-identical subunits; 2 rings are comprised of 7 alpha subunits and 2 rings are comprised of 7 beta subunits. Proteasomes are scattered all over eukaryotic cells at a high concentration and cleave peptides in an ATP/ubiquitin-dependent manner in a non-lysosomal pathway. The processing of class I MHC peptides is a vital function of the immunoproteasome (which is a modified proteasome).

Gankyrin (proteasome 26S subunit) is a multicatalytic proteinase oncoprotein commonly overexpressed in most hepatocellular carcinomas. Proteasomes are found throughout eukaryotic cells at a high concentrations and cleave peptides in an ATP/ubiquitin-dependent process in a non-lysosomal pathway. Gankyrin interacts with S6 ATPase of the 19S regulatory particle of the 26S proteasome. Gankyrin is involved in theregulation of the phosphorylation of the retinoblastoma protein by CDK4, and to enhance the ubiquitinylation of p53 by MDM2. Gankyrin consists of 7 ankyrin repeats and is structurally similar to I kappa Bs. Gankyrin acts as a regulatory subunit of the 26s proteasome which is involved in the atp-dependent degradation of ubiquitinated proteins. Gankyrin is involved in progression of esophageal squamous cell carcinoma. gankyrin plays an oncogenic role especially in early stages of human epatocarcinogenesis. Gankyrin binds to NF-kappaB and suppresses its activity at the transcription level by modulating acetylation through SIRT1. Structural comparison between Gankyrin & p16(INK4A) identified numerous residues of gankyrin that are potentially important for CDK4 binding.

The proteasome is a multicatalytic proteinase complex with a highly assembled ring-shaped 20S core structure which is composed of 4 rings of 28 non-identical subunits, 2 rings are composed of 7 alpha subunits and 2 rings are composed of 7 beta subunits. Proteasomes are found throughout eukaryotic cells at a high concentration and cleave peptides in an ATP/ubiquitin-dependent process in a non-lysosomal pathway. PSMA7 is part of the peptidase T1A family, that is a 20S core alpha subunit. PSMA7 interacts particularly with the hepatitis B virus X protein, a protein critical to viral replication. PSMA7 is involved in regulating hepatitis virus C internal ribosome entry site activity that is crucial for viral replication. PSMA7 is in charge for regulating the hypoxia-inducible factor-1alpha, a transcription factor important for cellular responses to oxygen tension. PSMA7 is characterized by its ability to cleave peptides with Arg, Phe, Tyr, Leu, and Glu adjacent to the leaving group at neutral or slightly basic pH. PSMA7 interacts specifically with two subdomains of HIF-1alpha and inhibited the transactivation function of HIF-1alpha under both normoxic and hypoxia-mimicking conditions.

The 26S proteasome is a multicatalytic proteinase complex with a well ordered structure composed of two complexes- a 20S core and a 19S regulator. PSMD11 is a non-ATPase subunit of the 19S regulator. The 20S core is composed of four rings of 28 non-identical subunits; two rings are composed of 7 alpha subunits and two rings are composed of 7 beta subunits. The 19S regulator is composed of a base that contains six ATPase subunits and two non-ATPase subunits, and a lid that contains up to ten non-ATPase subunits. Proteasomes are spread throughout eukaryotic cells at a high concentration and cleave peptides in an ATP/ubiquitin-dependent process in a non-lysosomal pathway. An indispensable function of a modified proteasome, the immunoproteasome, is the processing of class I MHC peptides.

The 26S proteasome is a multicatalytic proteinase complex with a well ordered structure composed of two complexes- a 20S core and a 19S regulator. PSMD11 is a non-ATPase subunit of the 19S regulator. The 20S core is composed of four rings of 28 non-identical subunits; two rings are composed of 7 alpha subunits and two rings are composed of 7 beta subunits. The 19S regulator is composed of a base that contains six ATPase subunits and two non-ATPase subunits, and a lid that contains up to ten non-ATPase subunits. Proteasomes are spread throughout eukaryotic cells at a high concentration and cleave peptides in an ATP/ubiquitin-dependent process in a non-lysosomal pathway. An indispensable function of a modified proteasome, the immunoproteasome, is the processing of class I MHC peptides.

Ubiquitin-like domain-containing CTD phosphatase 1 (UBLCP1) dephosphorylates 26S nuclear proteasomes, thereby decreasing their proteolytic activity. The dephosphorylation averts assembly of the core and regulatory particles (CP and RP) into mature 26S proteasome.

PSME1 is an interferon gamma (IFNG) inducible proteasome activator essential for presentation of certain major histocompatibility (MHC) class I antigens. The PSME1 complex is an alternate proteasome activator which operates with no use of ubiquitin. The PSME1 complex is made out of two homologous subunits, alpha and beta, that functions in similar catalytic properties and is connected to a hexameric ring.

Gankyrin (proteasome 26S subunit) is a multicatalytic proteinase oncoprotein commonly overexpressed in most hepatocellular carcinomas. Proteasomes are found throughout eukaryotic cells at a high concentrations and cleave peptides in an ATP/ubiquitin-dependent process in a non-lysosomal pathway. Gankyrin interacts with S6 ATPase of the 19S regulatory particle of the 26S proteasome. Gankyrin is involved in theregulation of the phosphorylation of the retinoblastoma protein by CDK4, and to enhance the ubiquitinylation of p53 by MDM2. Gankyrin consists of 7 ankyrin repeats and is structurally similar to I kappa Bs. Gankyrin acts as a regulatory subunit of the 26s proteasome which is involved in the atp-dependent degradation of ubiquitinated proteins. Gankyrin is involved in progression of esophageal squamous cell carcinoma. gankyrin plays an oncogenic role especially in early stages of human epatocarcinogenesis. Gankyrin binds to NF-kappaB and suppresses its activity at the transcription level by modulating acetylation through SIRT1. Structural comparison between Gankyrin & p16(INK4A) identified numerous residues of gankyrin that are potentially important for CDK4 binding.

Proteasomal ubiquitin receptor ADRM1 (ADRM1) functions as a proteasomal ubiquitin receptor. ADRM1 is an integral plasma membrane protein which promotes cell adhesion. ADRM1 is assumed to undergo O-linked glycosylation. ADRM1 gene expression is induced by gamma interferon in some cancer cells. ADRM1 employs the deubiquitinating enzyme UCHL5 at the 26S proteasome and promotes its activity.

Proteasomal ubiquitin receptor ADRM1 (ADRM1) functions as a proteasomal ubiquitin receptor. ADRM1 is an integral plasma membrane protein which promotes cell adhesion. ADRM1 is assumed to undergo O-linked glycosylation. ADRM1 employs the deubiquitinating enzyme UCHL5 at the 26S proteasome and promotes its activity.

STUB1, is a cytoplasmic protein whose amino acid sequence is highly preserved across species. STUB1 interacts with the molecular chaperones Hsc70-Hsp70 and Hsp90 through its TPR domain, whereas its U-box domain contains its E3 ubiquitin ligase activity. STUB1 interaction with these molecular chaperones lead to in client substrate ubiquitylation and degradation by the proteasome. therefore, STUB1 acts to tilt the folding-refolding mechanism towards the degradative pathway, and it serves as a link between the two. STUB1 inhibits anchorage-independent cell growth and metastatic potential by degrading oncogenic proteins including SRC-3. Inhibition of tyrosine kinase activity of Her-2/neu by quercetin specifies an lateration in the Her-2/neu structure which promotes STUB1 recruitments and down-regulation of Her-2/neu. STUB1 recognizes and mediates degradation of toxic, oligomeric forms of alphaSyn.

Ubiquilin-2, also known as UBQLN2 contains an N-terminal ubiquitin-like domain and a C-terminal ubiquitin-associated domain. UBQLN2 is physically linked with proteasomes as well as ubiquitin ligases, and therefore is considered to functionally connect the ubiquitination machinery to the proteasome in order to affect in vivo protein degradation. Furthermore, UBQLN2 binds the ATPase domain of the Hsp70-like Stch protein. Among the diseases which are associated with UBQLN2: Amyotrophic lateral sclerosis 15, with or without frontotemporal dementia as well as Amyotrophic lateral sclerosis type 15.

Otubain 1 (OTUB1) belongs to the ovarian tumor (OUT) superfamily of predicted cysteine proteases and inhibits cytokine gene transcription in the immune system through its interaction with a ubiquitin protease and E3 ubiquitin ligase. OTUB1 is a highly specific ubiquitin iso-peptidase, it cleaves ubiquitin from branched poly-ubiquitin chains but not from ubiquitinated substrates. OTUB1 is believed to work in specific ubiquitin-dependent pathways, possibly by providing an editing function of polyubiquitin chain growth. OTUB1 is a hydrolase that removes conjugated ubiquitin from proteins in vitro and may therefore have a significant regulatory role in the level of protein turnover by preventing degradation. Additionally, OTUB1 is a regulator of T-cell anergy, a phenomenon that occurs when T-cells are rendered impassive to antigen re-challenge and no longer respond to their cognate antigen. OTUB1 acts via its interaction with RNF128/GRAIL, which is an essential inductor of CD4 T-cell anergy.

UBE2E1 belongs to the E2 ubiquitin-conjugating enzyme family. UBE2E1 accepts ubiquitin from the E1 complex and catalyzes its covalent attachment to other proteins. UBE2E1 catalyzes the covalent attachment of ISG15 to other proteins. UBE2E1 mediates the selective degradation of short-lived and abnormal proteins. In vitro, UBE2E1 also catalyzes 'Lys-48'-linked polyubiquitination.

UCHL5 is a member of the peptidase C12 family. UCHL5 protein is a protease that specifically cleaves 'Lys-48'-linked polyubiquitin chains, and deubiquitinating enzyme related to the 19S regulatory subunit of the 26S proteasome.

26S proteasome complex subunit DSS1 (SHFM1) has been suggested as a candidate gene for the autosomal dominant form of the heterogeneous limb developmental disorder split hand/split foot malformation type 1. SHFM1 is a subunit of the 26S proteasome which plays a part in ubiquitin-dependent proteolysis. SHFM1 binds and stabilizes BRCA2 and is therefore involved in the control of R-loop-associated DNA damage and thus transcription-associated genomic instability. Furthermore, SHFM1 may have a role in the completion of the cell cycle. SHFM1 is a component of the TREX-2 complex (transcription and export complex 2), comprised of at least ENY2, GANP, PCID2, DSS1, and either centrin CETN2 or CETN3.

Human Ubquitin Conjugating Enzyme 7 (UbcH7) is a class I enzyme which functions in the stress response and the control of transcription factors. The enzyme is ubiquitously expressed with high levels of expression seen in adult muscle. UbcH7 mediates the selective degradation of short-lived and abnormal proteins and is highly homologous to UbcH5. It has been demonstrated to participate in the ubiquitinylation of p53, c-Fos and NF-?B. UbcH7 is one of two E2s (UbcH5 being the other) with which HECT domain proteins interact with UbcH7 being able to efficiently substitute for UbcH5 in E6-AP-dependent ubiquitinylation.

SQSTM1 is an adapter protein which binds ubiquitin and mediates the activation of NFKB1 by TNF-a, NGF and IL-1. SQSTM1 is involved in titin/TTN downstream signaling in muscle cells. SQSTM1 controls signaling cascades through ubiquitination. SQSTM1 participates in cell differentiation, apoptosis, immune response and regulation of K(+) channels. Mutations in UBA domain of the SQSTM1 protein cause Paget’s disease because the UBA is essential for aggregate sequestration and cell survival.

Nucleosome core proteins are a group of proteins which are necessary for DNA packaging in eukaryotes. Every core contains an octamer with 2 copies of each histone 2A, 2B, 3 and 4 around which an approx. 140 bp section of DNA is wound twice.

Streptavidin is a tetrameric protein secreted by Streptomyces avidinii which binds firmly to biotin. Streptavidin is widely used in molecular biology through its unique high affinity for the vitamin biotin. The dissociation constant (Kd) of the biotin-streptavidin complex is about ~10-15 mol/L. The strong affinity recognition of biotin and biotinylated molecules has made streptavidin one of the most important components in diagnostics and laboratory kits. The streptavidin/biotin system has one of the biggest free energies of association of yet observed for noncovalent binding of a protein and small ligand in aqueous solution (K_assoc = 10**14). The complexes are also extremely stable over a wide range of temperature and pH.