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Synovial Sarcoma, X Breakpoint 1 (SSX1) is a member of a family of highly homologous synovial sarcoma X (SSX) breakpoint proteins. SSX proteins are localized to the nucleus and expressed in testis and some types of cancers and, hence, they are classified as C/T (cancer/testis) antigens. These proteins may serve as transcriptional repressors. SSX1 genes are involved in the t (X;18) translocation typically found in all synovial sarcomas. This translocation leads to the fusion of the synovial sarcoma translocation gene on chromosome 18 to one of the SSX genes on chromosome X. These hybrid proteins are most likely responsible for transforming activity.

C3d is derived from human C3 after a series of proteolytic cleavages.C3d is prepared from purified human C3. The C3 is converted to C3b by treatment with the natural human C3 convertase and this C3b is converted to iC3b. Finally, this iC3b is cleaved with trypsin to yield C3d.If the C3b precursor was attached to a surface (as occurs during complement activation) the iC3b, C3dg and C3d fragments would remain covalently attached to that surface.C3d is able to attach to a surfaceonly during complement activation on a surface. Surface-bound C3d is linked to the target through an ester or an amide covalent bond. Ester bonds are unstable, thusC3d releasesfrom the particle.

Proteasome assembly chaperone 2 (PSMG2) stimulates assembly of the 20S proteasome as part of a heterodimer with PSMG1. The PSMG1-PSMG2 heterodimer binds to the PSMA5 and PSMA7 proteasome subunits and promotes compilation of the proteasome alpha subunits into the heteroheptameric alpha ring and prevents alpha ring dimerization. PSMG2 is widely expressed with highest levels in the lung, brain and colon. It is moderately expressed in the muscle, stomach, spleen and heart, and weakly expressed in the small intestine, pancreas and liver. It is also highly expressed in hepatocellular carcinomas with low levels in surrounding liver tissue.

Parathymosin, also known as PTMS is a member of the pro/parathymosin family. PTMS may mediate immune function by blocking the effect of prothymosin alpha which confers resistance to particular opportunistic infections. Among the diseases associated with PTMS are hepatitis b, and alzheimer's disease.

Though the exact role of MMACHC is unknown, its C-terminal region shows similarity to TonB, which is a bacterial protein involved in energy transduction for cobalamin (vitamin B12) uptake. Therefore, it is suggested that MMACHC may have a role in the binding and intracellular trafficking of cobalamin. MMACHC mutations are linked with methylmalonic aciduria and homocystinuria type cblC. MMACHC is widely expressed, it is expressed at higher level in the fetal liver, however it is also expressed in the spleen, lymph node, thymus and bone marrow. MMACHC is weakly or not expressed in the peripheral blood leukocytes.

DENR takes part in the translation of target mRNAs by scanning and recognizing the initiation codon. DENR protein is involved in the intonation of the translational profile of a subset of cancer-related mRNAs when engaged to the translational initiation complex by the oncogene MCTS1.

BAG1 binds to BCL2 and is also called BCL2-associated athanogene. BAG1 increases the anti-apoptotic effects of BCL2 and is characterizes as a link between growth factor receptors and anti-apoptotic mechanisms. BAG1 inhibits the chaperone activity of HSP70/HSC70 by promoting substrate release. BAG1 inhibits the pro-apoptotic function of PPP1R15A, and has anti-apoptotic activity. BAG1 enhances the anti-cell death function of BCL2 induced by various stimuli.

BCL2-Like 1 (BCL2L1) belongs to the BCL-2 protein family. BCL2L1 is found at the outer mitochondrial membrane controls outer mitochondrial membrane channel (VDAC) opening. In addition, BCL2L1 regulate s a switch between cell death modes during mitotic arrest.

Ribosomes, the organelles which catalyze protein synthesis, contain a small 40S subunit and a large 60S subunit. Together these subunits are composed of 4 RNA species and nearly 80 structurally different proteins. RPL35A is a component of the 60S subunit of the ribosomal protein and a member of the L35AE family of ribosomal proteins. RPL35A is situated in the cytoplasm. The rat protein is known to bind to both initiator and elongator tRNAs, therefore, it is located at the P site, or P and A sites, of the ribosome. Though RPL35A was initially mapped to chromosome 18, it has been proven that it is located at 3q29-qter. Transcript variants utilizing alternative transcription initiation sites and alternative polyA signals exist. As is typical for genes encoding ribosomal proteins, there are several processed pseudogenes of this gene spread all over the genome.

Cyclophilin B (also known as PPIB, peptidylpropyl isomerase B) is a cyclosporine-binding protein and is mainly located within the endoplasmic reticulum. It is associated with the secretory pathway and released in biological fluids. This protein can bind to cells derived from T- and B-lymphocytes, and may regulate cyclosporine A-mediated immunosuppression.

SAP18 is a component of the histone deacetylase complex which has a significant role in the regulation of eukaryotic gene expression. SAP18 directly interacts with SIN3 and enhances SIN3-mediated transcriptional repression once bound to the promoter. SAP18 plays an important part in gene-specific recruitment of the HDAC complex by a number of transcription factors including Gli, GAGA, and Bicoid. Histone acetylation is significant in the regulation of eukaryotic gene expression. Histone acetylation and deacetylation is catalyzed by multisubunit complexes. SAP18 is a component of the histone deacetylase complex, which includes SIN3, SAP30, HDAC1, HDAC2, RbAp46, RbAp48, and other polypeptides. SAP18 is a component of a splicing-dependent multiprotein EJC (exon junction complex) placed at splice junction on mRNAs.

Ubiquitin-like modifier activating enzyme 5 (UBA5) is a member of the ubiquitin-activating E1 family and UBA5 subfamily. Ubiquitin and ubiquitin-like proteins are recognized as covalently conjugated to various cellular substrates by a three-step enzymatic pathway. The ubiquitin-activating enzyme (E1) has a vital role in the first step of ubiquitination pathway to activate ubiquitin or ubiquitin-like proteins. UBA5 activates an ubiquitin-like protein, ubiquitin-fold modifier 1 (Ufm1), by forming a high-energy thioester bond. UBA5 is located primarily in cytoplasm, while it generally localizes to the nucleus in presence of SUMO2.

PDCD4 is restricted to the nucleus in proliferating cells. Expression of PDCD4 is modulated by cytokines in natural killer and T cells. PDCD4 takes part in apoptosis. PDCD4 is a translation inhibitor targeted for degradation during tumor promotion. PDCD4 promotes colonic neoplastic transformation and tumor invasion. PDCD4 is an important target for microrna R-21 in breast cancer cells. Shortage of PDCD4 expression is associated with colorectal cancer.
PDCD4 is swiftly phosphorylated by S6K1 kinase protein & afterwords degraded by ubiquitin ligase SCF in response to mitogens.
PDCD4 in response to mitogens allows competent protein synthesis & cell growth. PDCD4 is a proapoptotic protein involved in TGF-beta1-induced apoptosis in human HCC cells, and a tumor suppressor in hepatocarcinogenesis. PDCD4 restraines tumor progression in colon carcinoma cells by the novel mechanism of down-regulating MAP4K1 transcription, with consequent inhibition of c-Jun activation and AP-1-dependent transcription.
Overexpression of PDCD4 in carcinoid cells results in inhibition of cell proliferation.

EMG1 is a 244 aa protein which has a role in ribosome biogenesis. EMG1 is a key protein in the small ribosomal subunit assembly, controls methylation during ribosome synthesis and takes part in pre-18S rRNA processing. EMG1 is localized to the nucleolus and a mutation in this gene is linked with Bowen-Conradi syndrome.

rRNA-processing protein UTP23 homolog (UTP23) is a small subunit (SSU) processome component. The SSU processome is a complex involved in ribosome biogenesis and essential for pre-18S rRNA maturation. UTP23 is vital for the first 3 cleavage steps in 18S rRNA maturation. Furthermore, single-point mutations in the conserved putative active site of Utp24 but not Utp23 annul its function in ribosome biogenesis.

Alpha 1 ACT is an early-stage acute-phase plasma protein and a serpin that preferentially inactivates chymotrypsin, cathepsin G, and chymase. Alpha-1-ACT, a serine protease inhibitor, is tightly associated with amyloid plaques in Alzheimer's disease (AD) and in normal aged human and monkey brain.
Regulation of the serine proteases and serine protease inhibitors plays an important role in neuromuscular differentiation. Prostate specific antigen (PSA), a chymotrypsin-like serine protease, is predominantly complexed to Alpha-1-ACT.

PMP2 is a small protein found in peripheral nerve myelin and spinal cord myelin, belongs to a family of fatty acid binding proteins. PMP2 partly decreases the inhibitory effect of T suppressors in the culture of immune lymph node cells. PMP2 protein is a lipid transport protein in schwann cells.

Methionyl Aminopeptidase 1D (METAP1D) is a part of the peptidase M24A family. METAP1D which is overexpressed in colon cancer cell lines participates in tumorigenesis. METAP1D eliminates methionine from the N-terminus of nascent proteins.

S100P is a Ca2+ binding protein that is part of the S100 family of proteins containing 2 EF-hand calcium-binding motifs. S100 proteins are found in the cytoplasm and/or nucleus of a large range of cells, and participates in the regulation of a number of cellular function such as cell cycle progression and differentiation. S100P participates in numerous biological functions but the exact functions or mechanism of its action is still mostly unknown. Once S100P binds calcium ions it goes through a conformational change that results in an exposure of a hydrophobic surface which permits the interaction with specific target proteins.

TPD52L1 (hD53, hD53L1) is a member of D52 gene family and overexpressed in human breast carcinoma. TPD52L1 contains coiled-coil motif, which is responsible for homo- and heteromeric interaction, and may be a regulator of cell proliferation and calcium-mediated signal transduction.
Moreover, TPD52L1 interacts with the mitogen-activated protein kinase kinase kinase 5 (MAP3K5/ASK1) and positively regulates MAP3K5-induced apoptosis.

UPP1 catalyzes the reversible phosphorylytic cleavage of uridine and deoxyuridine to uracil and ribose- or deoxyribose-1-phosphate which are used as carbon and energy sources or in the release of pyrimidine bases for nucleotide synthesis. UPP1 is part of the family of glycosyltransferases, specifically the pentosyltransferases. Pyrimidine nucleoside phosphorylases add ribose or deoxyribose to pyrimidine bases to form nucleosides that can be incorporated into RNA or DNA.

Cysteine-rich PDZ-binding protein, also known as CRIPT, takes part in the cytoskeletal anchoring of DLG4 in excitatory synapses.

The ribosomal phosphoproteins, also called P protein antigens, are associated with the large ribosomal subunit and therefore are antigenic targets with a cytoplasmic localization. Three P proteins have been described: P0 with a molecular weight of 35 kDa, P1 (19 kDa) and P2 (17 kDa). RPLP0 is a ribosomal protein that is a component of the 60S subunit. RPLP0 belongs to the L10P family of ribosomal proteins. RPLP0 is a neutral phosphoprotein having a C-terminal end that is nearly identical to the C-terminal ends of the acidic ribosomal phosphoproteins P1 & P2. The P0 protein interacts with P1 and P2 to form a pentameric complex consisting of P1 and P2 dimers, and a P0 monomer. As is typical for genes encoding ribosomal proteins, there are multiple processed pseudogenes of RPLP0 scattered throughout the genome.
Autoantibodies against ribosomal P proteins are present in 10 % of SLE patients. If anti-ribosomal P antibodies were to occur in the absence of other typical SLE associated autoantibodies, they may account for some patients with so-called ANA-negative lupus. It has been reported that lupus patients positive for anti-ribosomal P autoantibodies have a high frequency of CNS involvement, suggesting a marker use for these antibodies.

Insulin-Degrading Enzyme (IDE) is a zinc metallopeptidase which degrades intracellular insulin, and thus terminates insulins activity, as well as playing a part in intercellular peptide signaling by degrading various peptides such as amylin, bradykinin, and kallidin. The preferential affinity of the IDE enzyme for insulin results in insulin-mediated inhibition of the degradation of additional peptides such as beta-amyloid. Deficiencies in IDE protein's function are linked with Alzheimer's disease and type 2 diabetes mellitus nevertheless mutations in the IDE gene have not been demonstrated to be causative for these diseases. Insulin-Degrading Enzyme localizes mainly to the cytoplasm however in some cell types it localizes to the extracellular space, cell membrane, peroxisome, and mitochondrion. In addition, IDE degrades amyloid formed by APP and IAPP. Furthermore, IDE plays a part in the degradation and clearance of naturally secreted amyloid beta-protein by neurons and microglia.