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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.

TRAIL Receptor-3, also known as TNFRSF10C belongs to theTNF-receptor super family. TNFRSF10C contains an extracellular TRAIL-binding domain as well as a transmembranedomain, however no cytoplasmic death domain. Furthermore, TNFRSF10C is not capable of inducing apoptosis, and is considered toact as an antagonistic receptor which protects cells from TRAIL-induced apoptosis.

Caspase 3 Apoptosis-Related Cysteine Peptidase (CASP3) belongs to the cysteine-aspartic acid protease (caspase) family. Sequential activation of caspases plays a key role in the execution-phase of cell apoptosis. Caspases exist as inactive proenzymes which undergo proteolytic processing at conserved aspartic residues to generate 2 subunits, large and small, that dimerize to create the active enzyme. CASP3 protein cleaves and activates caspases 6, 7 and 9, and the protein itself is processed by caspases 8, 9 and 10. CASP3 is the leading caspase involved in the cleavage of amyloid-beta 4A precursor protein, which is linked with neuronal death in Alzheimer's disease. In addition, CASP3 is involved in the cleavage of huntingtin. CASP3 also cleaves and activates sterol regulatory element binding proteins (SREBPs) between the basic helix-loop-helix leucine zipper domain and the membrane attachment domain. CASP3 initiates cell adhesion in sympathetic neurons through RET cleavage.

Ro 60 kDa autoantigen is an RNA-binding protein that binds to several small cytoplasmic RNA molecules known as Y RNAs. SSA2 may stabilize these RNAs from degradation. Sera taken from patients with Systemic Lupus Erythematosus (SLE) often contains antibodies that react with the normal cellular SSA2 protein as if this antigen was foreign.

Hydroxymethylglutaryl-CoA lyase (HMGCL) is a mitochondrial matrix protein which is a member of the HMG-CoA lyase family. HMGCL is a homodimer and participates in leucine catabolism and ketogenesis, the hepatic synthesis of ketone bodies which, during fasting, provides a major source of energy for the heart, brain and kidney. More precisely, HMGCL catalyzes the final step of these processes, the cleavage of 3-hydroxy-3-methylglutaryl-CoA to acetoacetic acid and acetyl-CoA.

a-Synuclein (amino acids 1-140), an acidic neuronal protein of 140 amino acids, is extremely heat-resistant and is natively unfolded with an extended structure primarily composed of random coils. a-synuclein has been suggested to be implicated in the pathogenesis of Parkinson’s disease and related neurodegenerative disorders, and more recently, to be an important regulatory component of vesicular transport in neuronal cells. Moreover, recent studies have shown that a-synuclein has chaperone activity and that this activity is lost upon removing its C-terminal acidic tail (amino acids 96-140).

CCL4L1 (C-C motif chemokine 4-like) is a member of to intercrine beta (chemokine CC) family. The CCL4L1 protein is similar to CCL4 which inhibits HIV replication in peripheral blood monocytes which express CCR5.

The proteasome is a multicatalytic proteinase complex which holds an extremely organized 20S core structure shaped like a ring. The central structure is assembled from 4 rings of 28 non-identical subunits; 2 rings are composed of 7 alpha subunits and 2 rings are composed of 7 beta subunits. There is a high concentration of proteasomes all over the eukaryotic cells and their job is to cleave peptides in an ATP/ubiquitin-dependent procedure in a non-lysosomal pathway. PSMA3 encodes several of the peptidase T1A family which is a 20S core alpha subunit. Two alternative transcripts encoding diverse isoforms were recognized.

TNFAIP8 which is a part of the TNFAIP8 family acts as a negative mediator of apoptosis and takes part in tumor progression. TNFAIP8 suppresses the TNF-mediated apoptosis by inhibiting caspase-8 activity but not the processing of procaspase-8, resulting in inhibition of BID cleavage and activation of caspase-3.

Mitochondrial Ribosome Recycling Factor (MRRF) is a member of the RRF family. MRRF attaches to the large ribosomal subunit in the cleft which has a peptidyl transferase center. MRRF controls the release of ribosome from messenger RNA at the termination of protein biosynthesis. Also, it may intensify the efficacy of translation by recycling ribosome from one round of translation to another.

Ketosamine-3-kinase (FN3KRP) catalyzes the phosphorylation of psicosamines and ribulosamines compared to the adjacent gene which encodes a highly analogous enzyme, fructosamine-3-kinase that has different substrate specificity. The activity of both enzymes may cause deglycation of proteins to reinstate their function. A high concentration of glucose can result in non-enzymatic oxidation of proteins by reaction of glucose and lysine residues (glycation). The proteins altered in this way, are less active or functional.

YOD1 is a Hydrolase which removes conjugated ubiquitin from proteins and takes part in endoplasmic reticulum-associated degradation (ERAD) for misfolded lumenal proteins. YOD1 is a highly conserved deubiquitinating enzyme belonging to the ovarian tumor (otubain) family, whose function has yet to be determined in mammalian cells. YOD1 is a component of a multiprotein complex with p97 as its nucleus, proposing a functional link to a pathway responsible for the dislocation of misfolded proteins from the endoplasmic reticulum. YOD1 variant xpression deprived of its deubiquitinating activity compels a halt on the dislocation reaction, as concluded by the stabilization of various dislocation substrates.

TNF-related apoptosis-inducing ligand (TRAIL) is a ligand molecule which induces apoptosis. It is a type II transmembrane protein with homology to other members of the tumor necrosis factor family.
In humans, the gene that encodes for TRAIL is located at chromosome 3q26.
TRAIL binds to the death receptors, DR4 and DR5. The process of apoptosis is caspase-8-dependent. This protein preferentially induces apoptosis in transformed and tumor cells, but does not appear to kill normal cells although it is expressed at a significant level in most normal tissues.

Hepatoma-derived growth factor, related protein 3 (HDGFRP3/HDGF2) is the original member of a family of polypeptides labeled HDGF related proteins (HRPs). The HDGF2 protein augments DNA synthesis and may play a part in cell proliferation. HDGF2 is expressed primarily in the testis and the brain, to an intermediate extent in the heart, and to a slight extent in the ovaries, kidneys, spleen, and liver in humans.

GAP43 is a phosphoprotein of the presynaptic membrane that takes part in synaptic reorganization and neural development. GAP43 is found in large quantities in neuronal growth cones all through the development and axonal regeneration. Additionally, GAP43 is involved in specific regions of the normal adult nervous system and has a vital part in the conservation mechanism of long-term potentiation (LTP).

Dickkopf-related protein 3 (DKK3) belongs to the DKK protein family including Dkk-1, 2, 3 and -4. DKK3 is a 350 amino acid secreted glycoprotein which is comprised of an N-terminal signal peptide and 2 conserved cysteine-rich domains that are separated by a 12 amino acid linker region. DKK3 is involved in embryonic development through its inhibition of the WNT signaling pathway. DKK3 gene expression is decreased in a variety of cancer cell lines and it may act as a tumor suppressor gene.

TNF-related apoptosis-inducing ligand (TRAIL) is a ligand molecule which induces apoptosis. It is a type II transmembrane protein with homology to other members of the tumor necrosis factor family.
In humans, the gene that encodes for TRAIL is located at chromosome 3q26.
TRAIL binds to the death receptors, DR4 and DR5. The process of apoptosis is caspase-8-dependent. This protein preferentially induces apoptosis in transformed and tumor cells, but does not appear to kill normal cells although it is expressed at a significant level in most normal tissues.

Human TNFRSF10A is a type 1 transmembrane protein in the TNF R superfamily. TNFRSF10A is not expressed in rodents. The trimeric ligand Trail binds TNFRSF10A and induces apoptosis, and recombinant, soluble forms of the receptor inhibit Trail-induced apoptosis. TNFRSF10A is expressed generally in damaged, infected, and malignant cells. TNFRSF10A functions in immune surveillance, inducing apoptosis in cancer cells but not normal cells.

Charged Multivesicular Body Protein 5 (CHMP5) is a member of the chromatin-modifying protein/charged multivesicular body protein (CHMP) family. These proteins comprise the ESCRT-III (endosomal sorting complex required for transport III), a complex involved in degradation of surface receptor proteins and development of endocytic multivesicular bodies (MVBs). Certain CHMPs have both nuclear and cytoplasmic/vesicular distributions, and one such CHMP the CHMP1A, is essential for both MVB formation and regulation of cell cycle progression.

ATPase Transporting, Lysosomal V1 Subunit F (ATP6V1F) is a component of vacuolar ATPase (V-ATPase); it is a multi-subunit enzyme, which mediates acidification of eukaryotic intracellular organelles. V-ATPase dependent organelle acidification is required for such intracellular processes as protein sorting, zymogen activation, receptor-mediated endocytosis, and synaptic vesicle proton gradient generation. V-ATPase is comprised of a cytosolic V1 domain and a transmembrane V0 domain. The V1 domain contains 3 A and 3 B subunits, 2 G subunits as well as the C, D, E, F, and H subunits. The V1 domain has the ATP catalytic site. The V0 domain consists of 5 different subunits: a, c, c', c', and d.

Human Ubquitin Conjugating Enzyme 9 (Ubc9) is a member of the E2 family and is specific for the conjugation of SUMO to a variety of target proteins. SUMO conjugation to target proteins is mediated by a different, but analogous, pathway to ubiquitinylation. This E2 is unusual in that it interacts directly with protein substrates that are modified by sumolyation, and may play a role in substrate recognition. Ubc9 can mediate the conjugation of SUMO-1 to a variety of proteins including RanGAP1, I?B?, and PML without the requirement of an E3 ligase.

a-Synuclein (amino acids 1-140), an acidic neuronal protein of 140 amino acids, is extremely heat-resistant and is natively unfolded with an extended structure primarily composed of random coils. a-synuclein has been suggested to be implicated in the pathogenesis of Parkinson’s disease and related neurodegenerative disorders, and more recently, to be an important regulatory component of vesicular transport in neuronal cells. Moreover, recent studies have shown that a-synuclein has chaperone activity and that this activity is lost upon removing its C-terminal acidic tail (amino acids 96-140).

Obestatin is a hormone that is produced in the cells lining the stomach and small intestine of several mammals including humans; it drastically reduces appetite in mice and is expected to do the same in humans. Obestatin is a peptide hormone - a relatively small protein. It is encoded by the same gene that also encodes ghrelin, a peptide hormone that increases appetite. The protein produced by that gene breaks into two smaller peptides, ghrelin and obestatin. Ghrelin is an endogenous ligand for the growth hormone secretagogue receptor and is involved in regulating growth hormone release. Ghrelin is derived from a preprohormone called preproghrelin, which also generates a second peptide called obestatin. Ghrelin is an endogenous ligand for the orphan G protein-coupled receptor GPR39 and is involved in satiety and decreased food intake.

Secreted frizzled-related protein 4 (SFRP4) belongs to the SFRP family which contains a cysteine-rich domain homologous to the putative Wnt-binding site of Frizzled proteins. SFRPs serve as soluble modulators of Wnt signaling. SFRP4 may serve as a regulator of adult uterine morphology and function. SFRP4 increases apoptosis during ovulation possibly via modulation of FZ1/FZ4/WNT4 signaling. SFRP4 also has phosphaturic effects by specifically inhibiting sodium-dependent phosphate uptake. SFRP4 is expressed in proliferative endometrium and several types of ovarian, endometrial and Brest tumors. SFRP4 is expressed in mesenchymal cells and in cardiomyocytes. SFRP4 expression in ventricular myocardium correlates with apoptosis related gene expression. SFRP4 is up-regulated in failing myocardium.