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PSMB5 belongs to the proteasome B-type family that has a 20S core beta subunit in the proteasome. This catalytic subunit is not present in the immunoproteasome and is substituted by catalytic subunit 3i (proteasome beta 8 subunit). A fundamental function of a modified proteasome, the immunoproteasome, is the processing of class I MHC peptides. PSMB5 exhibits an ATP dependent proteolytic activity and is involved in an ATP/ubiquitin dependent non lysosomal proteolytic pathway.

Cysteine-Rich Secretory Protein 2 (CRISP2) regulates some ion channels activity and thereby regulates calcium fluxes during sperm capacitation. Amongst its related pathways are p53 signaling. Diseases related with CRISP2 include epididymitis and orchitis.

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.

MMADHC is a mitochondrial protein which takes part in an early step of vitamin B1 2 metabolism. Vitamin B12 (cobalamin) is vital for regular development and existence in humans. Mutations in MMADHC can result in methylmalonic aciduria and homocystinuria type cblD, a cobalamin metabolism syndrome which is characterized by decreased levels of the coenzymes methylcobalamin and adenosylcobalamin.

TCEB1 (elongin C) is a subunit of elongin, which is a common transcription elongation factor that increases the RNA polymerase II transcription elongation past template encoded arresting sites. The SIII complex is comprised of elongins A/A2, B and C. The SIII complex activates elongation by RNA polymerase II by curbing transient pausing of the polymerase at numerous sites within transcription units. Elongin A acts as the transcriptionally active component of the SIII complex, while elongins B and C are regulatory subunits. Elongin A2 is specifically expressed in the testis, and able to forming a stable complex with elongins B and C. The VHL (von Hippel-Lindau) tumor suppressor protein binds to elongins B and C, and thus inhibits transcription elongation.

VAPB Vesicle-associated membrane protein (VAMP)-associated protein B (aka VAPB) is a type IV transmembrane protein and belongs to the VAP family of proteins. VAPB may have a role in vesicle trafficking. VAPB is found in plasma and intracellular vesicle membranes as a homodimer and heterodimer with VAPA, and interacts with VAMP1 and VAMP2. VAPB defects are the basis for the amyotrophic lateral sclerosis type 8 and spinal muscular atrophy autosomal dominant Finkel type.

MAX protein is part of the basic helix-loop-helix leucine zipper (bHLHZ) family of transcription factors. MAX forms homodimers and heterodimers with Mad, Mxi1 and Myc. Myc is an oncoprotein implicated in cell proliferation, differentiation and apoptosis. The homodimers and heterodimers compete for a common DNA target site (the E box) and rearrangement among these dimer forms offers a complex system of transcriptional regulation. In contrast to Myc, which is exceedingly regulated throughout progression during the cell cycle, Max is very stable and is much more abundant than Myc.

Tripartite Motif Containing 33 (TRIM33) belongs to the tripartite motif family. This motif includes 3 zinc-binding domains, a RING, a B-box type 1 and a B-box type 2, and a coiled-coil region. TRIM33 is assumed to be a transcriptional corepressor. TRIM33 functions as an E3 ubiquitin-protein ligase. TRIM33 also promotes SMAD4 ubiquitination, nuclear exclusion and degradation via the ubiquitin proteasome pathway. In addition, TRIM33 inhibits the transcriptional response to TGF-beta/BMP signaling cascade. Furthermore, TRIM33 has a role in the control of cell proliferation.

MYC Induced Nuclear Antigen, also known as MINA is an oxygenase which can function both as a histone lysine demethylase and a ribosomal histidine hydroxylase. MINA is involved in the demethylation of trimethylated Lys-9 on histone H3 (H3K9me3), leading to an increase in ribosomal RNA expression. MINA also catalyzes the hydroxylation of 60S ribosomal protein L27a on His-39. In addition, MINA plays a significant role in cell growth and survival. MINA is implicated in ribosome biogenesis, probably in the duration of the assembly process of pre-ribosomal particles.

SUMO1 is a protein that belongs to the SUMO (small ubiquitin-like modifier) protein family. SUMO1 functions in a manner similar to ubiquitin in that it is bound to target proteins as part of a post-translational modification system. Still, unlike ubiquitin which targets proteins for degradation, SUMO1 is involved in a variety of cellular processes, for example nuclear transport, transcriptional regulation, apoptosis, and protein stability. SUMO1 is not active until the last four amino acids of the carboxy-terminus are cleaved off.

Tripartite Motif Containing 28 (TRIM28) which is a member of the tripartite motif family includes 3 zinc-binding domains, a RING, a B-box type 1 and a B-box type 2, and a coiled-coil region. TRIM28 mediates transcriptional control by interaction with the Kruppel-associated box repression domain found in many transcription factors. TRIM28 is restricted to the nucleus and connected with particular chromatin regions.

Regulation of nuclear pre-mRNA domain-containing protein 1B (RPRD1B) interacts with phosphorylated C-terminal heptapeptide repeat domain (CTD) of the largest RNA polymerase II subunit POLR2A, and participates in dephosphorylation of the CTD. RPRD1B stimulates binding of RNA polymerase II to the CCDN1 promoter and to the termination region before the poly-A site but decreases its binding after the poly-A site. RPRD1B inhibits RNA polymerase II from reading through the 3' end termination site and may allow it to be drafted back to the promoter through promotion of the formation of a chromatin loop. In addition, RPRD1B enhances the transcription of several other cell cycle-related genes including CDK2, CDK4, CDK6 and cyclin-E but not CDKN1A, CDKN1B or cyclin-A. RPRD1B also promotes cell proliferation.

Inositol monophosphatase 3 (IMPAD1) belongs to the inositol monophosphatase family. IMPAD1 is restricted to the Golgi apparatus and catalyzes the hydrolysis of phosphoadenosine phosphate (PAP) to adenosine monophosphate (AMP). IMPAD1 gene mutations cause the GRAPP type chondrodysplasia with joint dislocations, and a pseudogene of the IMPAD1 gene is located on the long arm of chromosome 1.

HOMER2 belongs to the homer family of dendritic proteins which are immediate early gene products who bind to group 1 metabotropic glutamate receptors (mGluRs), proteins associated to triggering intracellular calcium release. Additionally, HOMER2 conect mGluRs to the inositol triphosphate receptors (IP3R).

B lymphoid kinase (BLK) is a 55kDa tyrosine kinase with SH3, SH2, and catalytic domains which contain consensus sequences of the Src protein tyrosine kinase family. BLK is a nonreceptor tyrosine-kinase belonging to the src family of proto-oncogenes which are typically involved in cell proliferation and differentiation. The BLK protein is expressed specifically in the B cell lineage and has a role in the signal-transduction pathway which is restricted to B lymphoid cells. In addition, BLK stimulates ins. synthesis and secretion in response to glucose and increases the expression of several pancreatic beta-cell transcription factors.

The bone morphogenetic protein (BMP) receptors are a family of transmembrane serine/threonine kinases that include the type I receptors BMPR1A and BMPR1B and the type II receptor BMPR2. These receptors are also closely related to the activin receptors, ACVR1 and ACVR2. The ligands of these receptors are members of the TGF-beta superfamily. TGF-betas and activins transduce their signals through the formation of heteromeric complexes with 2 different types of serine (threonine) kinase receptors: type I receptors of about 50-55 kD and type II receptors of about 70-80 kD. Type II receptors bind ligands in the absence of type I receptors, but they require their respective type I receptors for signaling, whereas type I receptors require their respective type II receptors for ligand binding.

BIRC7 is a part of the inhibitor of apoptosis protein (IAP) family and contains a single copy of a baculovirus IAP repeat (BIR) as well as a RING-type zinc finger domain. The BIR domain is necessary for inhibitory activity & cooperates with caspases, while the RING finger domain sometimes increases anti-apoptotic activity but doesn’t inhibit apoptosis by itself. 2 transcript variants encoding diverse isoforms have been found for this gene. The 2 isoforms have dissimilar antiapoptotic characteristics, with isoform a protecting cells from apoptosis induced by staurosporine and isoform b defending cells from apoptosis induced by etoposide.
BIRC7 has direct contact with several caspases together with caspase-3, caspase-7, & caspase –9. BIRC7 inhibits the activation of caspase-9 induced by Apaf-1, cytochrome c, and dATP.

SET is part of a complex localized to the endoplasmic reticulum however is found in the nucleus. SET inhibits apoptosis following attack by cytotoxic T lymphocytes and can also enhance DNA replication of the adenovirus genome. SET inhibits acetylation of nucleosomes, particularly histone H4, by histone acetylases (HAT). This inhibition is accomplished by masking histone lysines from being acetylated.

ASF1 Anti-Silencing Function 1 Homolog B (ASF1B) belongs to the H3/H4 family of histone chaperone proteins and is similar to the anti-silencing function-1 protein in yeast. ASF1B is the substrate of the tousled-like kinase family of cell cycle-regulated kinases, and may have a crucial role in modulating the nucleosome structure of chromatin by guaranteeing a regular supply of histones at sites of nucleosome assembly. ASF1B cooperates with CAF-1 (chromatin assembly factor 1) to stimulate replication-dependent chromatin assembly. ASF1B is highly expressed in the testis and at lower levels in colon, small intestine and thymus. ASF1B is necessary for spermatogenesis.

Stomatin (STOM) is a part of a highly conserved family of integral membrane proteins. STOM is a membrane protein involved in regulation of monovalent cation transport through lipid membranes which regulates ACCN1 and ACCN3 gating. STOM is a major lipid-raft component of erythrocytes and epithelial cells, and an abundant platelet protein which acts as a cytoskeletal anchor.

SUMO1 is a protein that belongs to the SUMO (small ubiquitin-like modifier) protein family. SUMO1 functions in a manner similar to ubiquitin in that it is bound to target proteins as part of a post-translational modification system. Still, unlike ubiquitin which targets proteins for degradation, SUMO1 is involved in a variety of cellular processes, for example nuclear transport, transcriptional regulation, apoptosis, and protein stability. SUMO1 is not active until the last four amino acids of the carboxy-terminus are cleaved off.

Pirin (PIR) which belongs to the cupin superfamily, is an Fe(II)-containing nuclear protein expressed in all tissues of the body and concentrated within dot-like subnuclear structures. Pirin may function as a transcriptional cofactor and is involved in the regulation of DNA transcription and replication, as a result of interactions with nuclear factor I/CCAAT box transcription factor as well as B cell lymphoma 3-encoded oncoprotein.

Polymerase (DNA Directed), Epsilon 3, also know as POLE3, is a histone-fold protein which interacts with other histone-fold proteins to bind DNA in a sequence-independent manner. These histone-fold protein dimers merge into larger enzymatic complexes for DNA transcription, replication, and packaging.

Chromatin Accessibility Complex 1 (CHRAC1) is a histone-fold protein which interacts with further histone-fold proteins to bind DNA in a sequence-independent mode. These histone-fold protein dimers combine within larger enzymatic complexes for DNA replication, transcription, and packaging.