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The proteasome is a multicatalytic proteinase complex with an extremely organized ring-shaped 20S core structure. The core structure consists of 4 rings of 28 non-identical subunits; 2 rings consist of 7 alpha subunits and 2 rings consist of 7 beta subunits. Proteasomes are spread all over the eukaryotic cells in large quantities and cleave peptides in an ATP/ubiquitin-dependent procedure in a non-lysosomal pathway. A vital role of a modified proteasome, the immunoproteasome, is the handling of class I MHC peptides.

The La protein is a 47 kDa polypeptide that frequently acts as an autoantigen in systemic lupus erythematosus and Sjogren's syndrome patients. La is involved in various aspects of RNA metabolism, including binding and protecting 3-prime UUU(OH) elements of newly RNA polymerase III - transcribed RNA, processing 5-prime and 3-prime ends of pre-tRNA precursors, acting as an RNA chaperone, and binding viral RNAs linked to hepatitis C virus. It occurs in both the nucleus and the cytoplasm, where it assumes different roles. In the nucleus, La protein facilitates the production of tRNAs, acting as an RNA polymerase III (RNAP III) transcription factor by attaching to the U-rich 3'UTR of nascent transcripts, aiding in their folding and maturation. In the cytoplasm, La protein facilitates the translation of specific mRNAs, acting as a translation factor. As an RNA binding protein (RBP), La protein associates with subsets of mRNAs which contain a 5'-terminal oligopyrimidine (5'TOP) motif known to direct protein synthesis. The binding of La protein to particular classes of RNA molecules regulates their downstream processing, guards them from endonuclease digestion, and organizes their export from the nucleus. La/SS-B appears to be readily disposed to proteolysis, which results in many smaller (42kD, 320, and 270) nevertheless still immunoreactive polypeptides. La/SS-B antigen is strongly conserved across species. Anti-La/SS-B autoantibodies were originally found as precipitating autoantibodies in sera of Sjogren's Syndrome patients and referred to as SjT. Anti-La/SS-B precipitins are most frequently found in Sjogren's Syndrome, Systemic Lupus Erythematosus (SLE) and Subacute Cutaneous Lupus. Also, there seems to be a correlation between anti-La/SS-B and the absence of nephritis in SLE patients.

Aspartylglucosaminidase, also known as AGA, takes part in the catabolism of Nlinked oligosaccharides of glycoproteins. AGA is a protein coding gene which cleaves asparagine from N-acetylglucosamines in the lysosomal breakdown of glycoproteins.

Spindle And Kinetochore Associated Complex Subunit 1 (SKA1) is a part of the kinetochore-microtubule interface which associates with microtubules as oligomeric assemblies. The complex facilitates the processive movement of microspheres along a microtubule in a depolymerization-coupled manner. SKA1 is necessary for timely anaphase onset during mitosis, when chromosomes undergo bipolar attachment on spindle microtubules leading to silencing of the spindle checkpoint.

Kallikreins are a subgroup of serine proteases having various physiological functions. Many kallikreins are implicated in carcinogenesis and some have potential of becoming novel cancer and other disease biomarkers. Kallikrein-13 (KLK13) is one of the fifteen kallikrein subfamily members located in a cluster on chromosome 19. KLK13 gene expression is regulated by steroid hormones and may be useful as a marker for breast cancer.

SDF-1 (stromal cell-derived factor-1) is small cytokine belonging to the chemokine family that is officially designated Chemokine (C-X-C motif) ligand 12 (CXCL12). It is produced in two forms, SDF-1?/CXCL12a and SDF-1?/CXCL12b, by alternate splicing of the same gene. Chemokines are characterized by the presence of four conserved cysteines, which form two disulfide bonds. The CXCL12 proteins belong to the group of CXC chemokines, whose initial pair of cysteines are separated by one intervening amino acid. CXCL12 is strongly chemotactic for lymphocytes and has been implicated as an important cell co-ordinator during development. During embryogenesis it directs the migration of hematopoietic cells from foetal liver to bone marrow. Mice which were knocked-out for CXCL12 gene were lethal before the birth or within just 1 hour of life. As another role, CXCL12a alters also the electrophysiology of neurons. CXCL12 was shown to be expressend in many tissues in mice (including brain, thymus, heart, lung, liver, kidney, spleen and bone marrow).
The receptor for this chemokine is CXCR4, which was previously called fusin. This CXCL12-CXCR4 interaction used to be considered exclusive (unlike for other chemokines and their receptors), but recently it was suggested that CXCL12 is also bound by CXCR7 receptor.
The gene for CXCL12 is located on human chromosome 10. In human and mouse both CXCL12 and CXCR4 show high identity of sequence: 99% and 90%, respectively.

Chemokine (C motif) ligand (XCL1) is a small cytokine belonging to the XC chemokine family that is also known as lymphotactin. It is found in high levels in spleen, thymus, intestine and peripheral blood leukocytes, and at lower levels in lung, prostate gland and ovary. Cellular sources for XCL1 include activated thymic and peripheral blood CD8+ T cells. This chemokine attracts T cells. In humans, XCL1 is closely related to another chemokine called XCL2, whose geneis found at the same locus on chromosome 1. XCL1 induces it chemotactic function by binding to a chemokine receptor called XCR1.

MBP is a major component of the myelin sheath of oligodendrocytes and Schwann cells in the nervous system, although, MBP-related transcripts are also present in the bone marrow and the immune system. These mRNAs emerge from the long MBP gene which holds three additional exons located upstream of the classic MBP exons. The Golli mRNAs contain three exons unique to Golli-MBP, spliced in-frame to one or more MBP exons. The second family of transcripts contains only MBP exons and produces the well characterized myelin basic proteins. MBP transcription unit is an essential part of the Golli transcription unit and the arrangement is important for the function and/or regulation of these genes.

SAA1 protein is an acute phase apolipoprotein reactant which is produced mostly by hepatocytes and under regulation of inflammatory cytokines. SAA1 (Serum amyloid A1) protein is produced mainly in the liver and circulates in low levels in the blood. The SAA1 seems to have a role in the immune system. SAA1 protein levels increase in the blood and other tissues under conditions of inflammation. SAA1 may facilitate the repair of injured tissues; it also acts as an antibacterial agent, and signals the migration of germ-fighting cells to sites of infection. SAA1 also functions as an apolipoprotein of the HDL complex.
Elevated levels of SAA1 ultimately affect secondary amyloidosis, extracellular amassing of amyloid fibrils, resulting from a circulating precursor, in a variety of tissues and organs. The most widespread type of amyloidosis appears secondary to chronic inflammatory disease, mainly rheumatoid arthritis. The SAA1 cleavage product a designated amyloid protein A is deposited systemically as amyloid in vital organs such as the liver, spleen, and kidneys in chronic inflammatory diseases patients. These deposits are extremely insoluble and resistant to proteolysis; they disrupt tissue structure and compromise performance.

Signal-Regulatory Protein Alpha, SIRPA belongs to the signal-regulatory-protein (SIRP) family, as well as the immunoglobulin super family. The members of the SIRP family are receptor-type transmembrane glycoproteins which are involved in the negative regulation of receptor tyrosine kinase-coupled signaling processes.
SIRPA can be phosphorylated by tyrosine kinases. The phospho-tyrosine residues of this PTP have been shown to recruit SH2 domain containing tyrosine phosphatases (PTP), and perform as substrates of PTPs. SIRPA take part in signal transduction mediated by a variety of growth factor receptors. CD47 has been shown to be a ligand for SIRPA.

The Casein kinase 2 (EC2.7.11.1) is a serine/threonine-selective protein kinasethat is a tetramer of two alpha subunits and two beta subunits. The alpha subunits have the catalytic kinase domain. Casein kinase 2 has been implicated in cell cyclecontrol, DNA repair, regulation of the circadian rhythmand other cellular processes. Casein kinase 2 activity has been reported to be activated following Wnt signaling pathwayactivation. A Pertussis toxin-sensitive G proteinand Disheveled appear to be an intermediary between Wnt-mediated activation of the Frizzled receptor and activation of casein kinase 2.
Mice that lack casein kinase 2 alpha prime have a defect in the morphology of developing sperm.

Serum-and glucocorticoid-regulated kinase (SGK1) is a serine/threonine protein kinase and a member of the “AGC” subfamily, which includes protein kinases A, G, and C. The SGK1 protein has an imperative role in activating specific potassium, sodium and chloride channels, suggesting a participation in the regulation of processes such as cell survival, neuronal excitability, and renal sodium excretion. SGK1 is activated in vitro by PDK-1 (3-phosphoinositide-dependent protein kinase-1) and in vivo in reaction to signals which activate phosphatidylinositol (PI) 3-kinase.

Midkine (MK) is the product of a retinoic acid responsive gene, MK, and is a member of a family of heparin binding factors. It contains 121 amino acid residues including 10 conserved cysteine residues, all of which appear to be disulphide linked.
Midkine is expressed during embryogenesis, showing an expression pattern that suggests functions in neurogenesis, cell migration, secondary organogenetic induction, and mesoderm-epithelial interaction.
The widespread downregulation of MK in the adult human is reverted in a number of cancers, in which polypeptides are able to act as both transforming growth factors and promoters of angiogenesis.
Midkine (MK), induces chemotaxis of human neutrophils and was found to trigger mobilization of intracellular calcium of these cells.
Midkine induces histamine release from rat peritoneal mast cells with a rapid response in a dose dependent manner.
Midkine is also a potent stimulator of collagen and glycosaminoglycan synthesis.

S100A8 is a part of the S100 family of proteins containing 2 EF-hand calcium-binding motifs. S100 proteins are localized in the cytoplasm and/or nucleus of a broad range of cells, and participate in the regulation of cellular processes such as cell cycle progression and differentiation. S100A8 plays a role in the inhibition of casein kinase and as a cytokine. S100A8 altered expression is related with cystic fibrosis disease. S100A8 is a calcium-binding protein that has antimicrobial activity against bacteria and fungi.S100A8 is crucial for resistance towards invasion by pathogenic bacteria. S100A8 up-regulates transcription of genes that are under the control of NF-kappa-B. S100A8 plays a role in the development of endotoxic shock in response to bacterial lipopolysaccharide. S100A8 endorses tubulin polymerization and promotes phagocyte migration and infiltration of granulocytes at sites of wounding. S100A8 takes part as a pro-inflammatory mediator in acute and chronic inflammation and up-regulates the release of IL8 and cell-surface expression of ICAM1.

MTPN is an ankyrin repeat protein, that stimulates protein synthesis and cardiomyocyte growth to commence cardiac hypertrophy by activating the NF-kappaB signaling cascade. Myotrophin participates in cerebellar morphogenesis and takes part in differentiation of cerebellar neurons, particularly of granule cells. High levels of MTPN are expressed in human dilated cardiomyopathic and ischemic hearts.

SEMG1 is the predominant protein in semen. The secreted protein takes part in the formation of a gel matrix which encases ejaculated spermatozoa. The prostate-specific antigen (PSA) protease processes SEMG1 into smaller peptides, with each possibly having a separate function. The proteolysis process breaks down the gel matrix and allows the spermatozoa to shift more freely. 2 transcript variants encoding different isoforms have been found for SEMG1.

SPG21 binds to the hydrophobic C-terminal amino acids of CD4 which take part in suppression of CD-4 dependant T cell activation. The interaction with CD4 is mediated by the noncatalytic alpha/beta hydrolase fold domain. SPG21 adapts the stimulatory activity of CD4. SPG21 is broadly expressed in diverse tissues including heart, brain, placenta, lung, liver, skeletal muscle, kidney and pancreas. Mutations in SPG21 cause Mast syndrome, an autosomal-recessive complicated form of hereditary spastic paraplegia characterized by dementia, thin corpus callosum and white matter abnormalities.

Fumarylacetoacetate hydrolase domain-containing protein 1 (FAHD1) is a member of the FAH family. FAHD1 is considered to have hydrolase activity and it uses Magnesium and Calcium as cofactors. It seems quite likely that the metal binding sites are involved in an enzymatic activity connected to the catabolism of aromatic amino acids.

Tachykinin-3 belongs to the substance P-related tachykinin family. Tachykinins are active peptides that stimulate neurons, induce behavioral responses, are effective vasodilators and secretagogues, and contract (directly or indirectly) many smooth muscles. TAC3 and its receptor are essential switches of regulator of human puberty, regulated by the brain through the release of the GnRH which starts a chain of processes which eventually lead to the production of sex hormones.
During pregnancy, the expression of TAC3 is restricted to the outer syncytiotrophoblast of the placenta, significant concentrations of TAC3 can be identified in plasma as early as week 9, and plasma concentrations of TAC3 are grossly elevated in pregnancy-induced hypertension and pre-eclampsia. Higher Tachykinin-3 concentrations in normotensive pregnant women may be caused by the advanced gestational age and/or the result of a negative interaction of other vasoactive substances. TAC3 has a role in the continuance of high placental blood flow in normal pregnancy.

The 14-3-3 family of proteins plays a key regulatory role in signal transduction, checkpoint control, apoptotic and nutrient-sensing pathways. 14-3-3 proteins are highly conserved and ubiquitously expressed. There are at least seven isoforms, ?, ?, ?, ?, ?, ? and ? that have been identified in mammals. The 14-3-3 tau, a subtype of the 14-3-3 family of proteins, was found in T Cells, brain and testes. This 14-3-3 tau is upregulated in patients with amyotrophic lateral sclerosis.

CNTF is a polypeptide hormone whose actions appear to be restricted to the nervous system where it promotes neurotransmitter synthesis and neurite outgrowth in certain neuronal populations. The protein is a potent survival factor for neurons and oligodendrocytes and may be relevant in reducing tissue destruction during inflammatory attacks. A mutation in this gene, which results in aberrant splicing, leads to ciliary neurotrophic factor deficiency, but this phenotype is not causally related to neurologic disease. In addition to the predominant monocistronic transcript originating from this locus, the gene is also co-transcribed with the upstream ZFP91 gene. Co-transcription from the two loci results in a transcript that contains a complete coding region for the zinc finger protein but lacks a complete coding region for ciliary neurotrophic factor.
CNTF is a survival factor for various neuronal cell types. Seems to prevent the degeneration of motor axons after axotomy.

The Casein kinase 2 (EC2.7.11.1) is a serine/threonine-selective protein kinasethat is a tetramer of two alpha subunits and two beta subunits. The alpha subunits have the catalytic kinase domain. Casein kinase 2 has been implicated in cell cyclecontrol, DNA repair, regulation of the circadian rhythmand other cellular processes.
Casein kinase 2 activity has been reported to be activated following Wnt signaling pathwayactivation. A Pertussis toxin-sensitive G proteinand Disheveled appear to be an intermediary between Wnt-mediated activation of the Frizzled receptor and activation of casein kinase 2.
Mice that lack casein kinase 2 alpha prime have a defect in the morphology of developing sperm.

HDAC2 is a member of the histone deacetylase family that performs through the construction of large multiprotein complexes and are in charge of the deacetylation of lysine residues on the N-terminal region of the core histones. HDAC2 forms transcriptional repressor complexes by relating to a diversity of proteins, like YY1- a mammalian zinc-finger transcription factor.
In addition, HDAC2 has a vital part in transcriptional regulation, cell cycle progression and developmental procedures.