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Crystallins are the main structural proteins of the vertebrate eye lens, where they maintain the transparency and refractive index of the lens. Crystallins are divided into 3 fprotein families, α, β, & γ families. Because lens central fiber cells lose their nuclei during development, these crystallins are prepared and then retained throughout life, making them extremely stable proteins. CRYBB1 is a beta basic group member and undergoes extensive cleavage at its N-terminal extension during lens maturation.

A natural cytotoxicity receptor (NCR) NKp46 has been shown to represent a novel NK cell-specific molecule involved in human NK cell activation. The natural cytotoxicity receptors (NCRs) are a recently characterized family of Ig-like activation receptors that appear to be major triggering receptors in tumor cell recognition. The three known NCRs include NKp46 and NKp30, which are expressed on circulating NKcells, and NKp44, which is expressed only on activating NK cells. NKp46 has been implicated in NK cell-mediated lysis of several autologous tumor cells, pathogen-infected cell lines and mononuclear phagocytes infected with an intracellular bacterium. The Lysis of tumor cells by NK-cells involves recognition by NKp46 of heparan sulfate moieties of membrane heparan sulfate proteoglycans. Furthermore, NKp46 is a surface receptor involved in NK-cell cell death by apoptosis. NKp46 has two extracellular Ig-like domains followed by a ~40 residue stalk region, a type I transmembrane domain, and a short cytoplasmic tail. The extracellular Ig-like domain of NKp46 (22-255aa) is purified by FPLC gel-filtration chromatography, after refolding of the isolated inclusion bodies in a redox buffer. In addition, engagement of the antigen with the monoclonal antibody stimulates intracellular calcium levels and the synthesis of cytokines. CD59 is an NKp46 coreceptor (by physical association) together they activate cytotoxicity of human NK-cells, their engagement results in tyrosine phosphorylation of CD3-zeta chains associated with NKp46. Reduced cell surface expression of NKp46 and other NK-cell receptors is linked to the impaired NK-cell cytolytic function in viremic HIV-1 infection.

Thermosensitive Gluconokinase, also known as IDNK is a 187 a.a protein which is a member of the gluconokinase gntK/gntV family. IDNK catalyzes theconversion of ATP and D-gluconate to ADP and 6-phospho-D-gluconate. In addition, IDNK is considered to take part in gender determination, deletion of the distal portion of 9p is able to lead to a development of male to female sex reversal, the phenotype of a female with a male X, Y genotype.

Mouse S100A15 is a protein of 104 amino acids with an expected molecular weight of 12,870 Dalton having 2 EF-hand calcium binding sites. The S100A15 expression is upregulated in cultured keratinocytes stimulated to differentiate by calcium or phorbol esters. S100A15 is expressed in the skin and keratinocytes.

EDF1 controls endothelial cell differentiation. EDF1 has a role as a bridging protein that interconnects regulatory proteins and the basal transcriptional machinery, thus modulating the transcription of genes that take part in endothelial differentiation. EDF1 binds calmodulin through its IQ domain and controls nitric oxide synthase activity via calmodulin sequestration in the cytoplasm. EDF1 is localized in adult liver, heart, adipose tissues, intestine and pancreas.

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.

BPI fold containing family A Member 1 (BPIFA1) belongs to the short subfamily of PLUNC family proteins and have homology only to the Nterminal domains of BPI. BPIFA1 is a secreted protein which is expressed in the secretory ducts and submucosal glands of tracheobronchial tissues. BPIFA1 binds to LPS (lipopolysaccharide) in nasal lavage fluid (NLF) which alludes to its role in the inflammatory response of the upper airways after exposure to irritants. BPIFA1 may also serve as a potential molecular marker for detection of micrometastasis in non-small-cell lung cancer. Decreased levels of BPIFA1 are observed in the NLF of smokers and people who have been exposed to reactive epoxy chemicals, which indicats that long-term exposure to airway irritants damages the production of BPIFA1 in the upper respiratory tract.

FAS / CD95 is a 36kDa transmembrane type I receptor, which belongs to the NF/NGF receptor super-family. It is a potent inducer of apoptosis in cells of the immune system upon interaction with its natural ligand, CD95L. Although the CD95/CD95L system could play a role in tumor regression, tumor cells seem to down-regulate CD95 expression as a mechanism of resistance to CD95L-induced killing by T lymphocytes and NK cells. The Fas antigen is expressed on the surface of various cell types, including activated T and B lymphocytes and T lymphoblastoid cell line. CD95 is also expressed in a broad panel of non-transformed cells outside the immune system.

Endothelial cells express three different vascular endothelial growth factor (VEGF) receptors, belonging to the family of receptor tyrosine kinases (RTKs). They are named VEGFR-1 (Flt-1), VEGFR-2 (KDR/Flk-1), VEGFR-3 (Flt-4). Their expression is almost exclusively restricted to endothelial cells, but VEGFR-1 can also be found on monocytes, dendritic cells and on trophoblast cells. The flt-1 gene was first described in 1990. The receptor contains seven immunoglobulin-like extracellular domains, a single transmembrane region and an intracellular splited tyrosine kinase domain. Compared to VEGFR-2 the Flt-1 receptor has a higher affinity for VEGF but a weaker signaling activity. VEGFR-1 thus leads not to proliferation of endothelial cells, but mediates signals for differentiation. Interestingly a naturally occuring soluble variant of VEGFR-1 (sVEGFR-1) was found in HUVE supernatants in 1996, which is generated by alternative splicing of the flt-1 mRNA. The biological functions of sVEGFR-1 still are not clear, but it seems to be an endogenous regulator of angiogenesis, binding VEGF with the same affinity as the full-length receptor.

XIAP Associated Factor 1 (XAF1) is a protein which binds to and counteracts the inhibitory effect of a member of the IAP (inhibitor of apoptosis) protein family. IAP proteins bind to and inhibit caspases which are activated in the course of apoptosis. The ratio of IAPs and proteins which interfere with their activity, such as the XAF1 protein, influence the progress of the apoptosis signaling pathway. Additionally, XAF1 inhibits anti-caspase activity of BIRC4. XAF1 induces cleavage and inactivation of BIRC4 independent of caspase activation. Furthermore, XAF1 mediates TNF-alpha-induced apoptosis and is involved in apoptosis in trophoblast cells.

Vacuolar protein sorting-associated protein 26A (VPS26A) is a vital element of the retromer complex, which is required to recover lysosomal enzyme receptors (IGF2R and M6PR) from endosomes to the trans-Golgi network. Furthermore, VPS26A is essential in the regulation of transcytosis of the polymeric immunoglobulin receptor (pIgR-pIgA). Expression analysis in yeast and mammalian cells reveal that VPS26A interacts directly with VPS35 that functions as the core of the retromer complex.

Complement factor H (CFH) is an important regulatory component of the alternative pathway of complement. CFH is prevents complement activation on host cells and tissues, mainly the kidney. CFH controls the formation and decay of the alternative pathway C3/C5 convertase and acts as a cofactor for factor I which proteolytically inactivates C3b when C3b is bound to factor H. The N-terminal 5 domains of CFH bind to C3b and inhibit binding of factor B thus reducing the formation of C3/C5 convertase. CFH also binds to preformed C3/C5 convertases and causes quick release of the catalytic subunit Bb. These activities are necessary for controlling the spontaneous activation of the alternative pathway amplification process in plasma. In addition, CFH controls the formation and decay of these enzymes when C3b is attached to the surface of particles.

SNRPD3 is a small nuclear ribonucleoprotein (snRNPs) that contains the spliceosome in eukaryotes. SNRPD3 is essential for pre-mRNA splicing and small nuclear ribonucleoprotein biogenesis. Alternative splicing happens in this locus and two transcript variants encoding the same protein were branded.

SF3B14 is a 125 amino acid nuclear protein which is a component of the splicing factor 3b complex. Splicing factor 3b is involved with s with both the U2 and U11/U12 small nuclear ribonucleoprotein complexes (U2 snRNP) of spliceosomes. SF3B14 which is required for the splicing of pre-mRNA enters the spliceosome and connect with the pre-mRNA branch site facilitating the interaction of snRNP with the branch sites of U2 and U12 of the 17S U2 and the 18S U11/U12 snRNP complex.

Mitogen-activated protein kinase 9 (MAPK9) belongs to the MAP kinase family. MAP kinases function as an integration point for numerous biochemical signals, and are involved in a broad variety of cellular processes such as proliferation, differentiation, transcription regulation and development. MAPK9 targets specific transcription factors, and consequently mediates immediate-early gene expression in response to diverse cell stimuli. As an active dimer, MAPK9 can translocate to the nucleus and control transcription through its effects on c-Jun, ATF-2, and other transcription factors. MAPK9 blocks the ubiquitination of tumor suppressor p53, and so it increases the stability of p53 in nonstressed cells.

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.

RAP1A is part of the family of RAS-related proteins which possess 50% amino acid identity with the classical RAS proteins and have various structural characteristics in common. RAP proteins differ from RAS proteins in their 61st amino acid, glutamine in RAS is replaced by threonine in RAP proteins. RAP1A induces morphological reversion of a cell line transformed by a Ras oncogene and counteracts the mitogenic function of Ras, since it can interact with Ras GAPs and RAF in a competitive manner.

RARRES2 is a secreted chemotactic protein that initiates chemotaxis through the ChemR23 G protein-coupled seven-transmembrane domain ligand. RARRES2 is upregulated by the synthetic retinoid tazarotene and found in a vast variety of tissues. RARRES2 acts as an adipokine, and is truncated on both termini from the proprotein. RARRES2 is structurally related to the cathelicidin precursors, cystatin C and kininogens. RARRES2 promotes calcium mobilization and chemotaxis of immature dendritic cells and macrophages. RARRES2 is secreted as a precursor of little biological activity, which requires proteolytic cleavage of its COOH-terminal domain to be exchangeed into a potent and highly specific agonist of ChemR23. RARRES2 signals via its receptor, ChemR23 (CMKLR1), as a positive regulator of adipocyte differentiation and metabolic function. The Chemerin receptor acts as a coreceptor for SIV and some primary HIV-1 strains. The Chemerin receptor has another ligand, called tazarotene-induced gene.

CUTA is the 179 amino acid mammalian homolog of the cutA E. coli protein and is ubiquitously expressed, particularly in brain tissue. CUTA participates in cellular tolerance to a broad range of divalent cations other than copper. The CUTA protein is a cytoplasmic protein, encoded by the single-gene operon and has been related to divalent cation tolerance.

Hemoglobin subunit gamma-2 (HBG2), is a member of the globin family. HBG2 belongs to the fetal hemoglobin subunit, which comprised of two alpha chains organized with 2 gamma chains. HBG2 Amplified fetal hemoglobin production in adults and improve the clinical severity of sickle cell disease and beta-thalassemia major.

CST4 is a member of the cystatin superfamily which contains proteins that hold multiple cystatin-like sequences. Several family members are active cysteine protease inhibitors, whereas others have lost or possibly never attained this inhibitory activity. CST4 strongly inhibits papain (non-competitively) and ficin, partially inhibits stem bromelain and bovine cathepsin C, however does not inhibit porcine cathepsin B or clostripain.

SRP14 is a ribonucleoprotein complex which mediates the directing of proteins to the endoplasmic reticulum. The “Alu domain” of SRP is comprised of the heterodimer of the SRP9 and SRP14 proteins that are bound to the 5' and 3' terminal sequences of SRP RNA. SRP9/14 binding may be critical to the transcription, maturation, nucleolus localization and transport of SRP RNA.

RAC1 is a GTPase which belongs to the RAS superfamily of small GTP-binding proteins. Members of this superfamily appear to regulate a diverse array of cellular events, including the control of cell growth, cytoskeletal reorganization, and the activation of protein kinases. RAC-1 regulates the actin cytoskeleton but also other cellular processes. RAC1 have been shown to be involved in the regulation of cell-cell adhesion.