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Centromere proteins are a group of proteins which form and/or mediate the function of centromeres, the central structures of chromosomes to which spindle fibers/microtubuli attach and pull the chromosomes apart in cell division. Currently, 9 centromere proteins are known and designated CENPA to CENP-I. Most of the centromere proteins are targets of autoantibodies, the anti-centromere antibodies.
CENPB is the most important of the centromeric autoantigens: it has a molecular weight of approx. 66 kDa and plays an important role in the formation of the centromeric chromatin. CENPB antibodies are present in the sera of up to 80% of patients with CREST syndrome.

GMPR2 is the single known metabolic step by which guanine nucleotides can be transformed to the pivotal precursor of both adenine and guanine nucleotides. GMPR2 catalyzes the permanent NADPH-dependent reductive deamination of GMP to IMP, and is involved in re-utilization of free intracellular bases and purine nucleosides.

GNMT is an enzyme that catalyzes the conversion of S-adenosyl-L-methionine with glycine to S-adenosyl-L-homocysteine and sarcosine. GNMT is located in the cytoplasm and acts as a homotetramer. Defects in the GNMT gene causes of GNMT deficiency (hypermethioninemia). GNMT affects DNA methylation by regulating the ratio of S-adenosylmethionine to S-adenosylhomocystine and is involved in the detoxification pathway in liver cells. GNMT expression is diminished in human hepatocellular carcinoma (HCC). GNMT catalyzes the methylation of glycine by using s- adenosylmethionine (adomet) to form n-methylglycine (sarcosine) with the concomitant production of s-adenosylhomocysteine (adohcy). GNMT plays an essential role in the regulation of tissue concentration of adomet and of metabolism of methionine.

Prosaposin (PSAP) is a precursor of 4 lysosomal saposin proteins (saposin A, B, C and D). Saposins are heat-stable glycoproteins which facilitate the catabolism of glycosphingolipids with short oligosaccharide groups. PSAP stimulates neurite outgrowth and increases choline acetyltransferase activity. Prosaposin exists both as a secretory protein and as an integral membrane protein and has neurotrophic activities. The secreted prosaposin is assumed to have additional functions in human milk, cerebrospinal fluid and seminal plasma. PSAP gene mutations are linked with Gaucher disease, Tay-Sachs disease, and metachromatic leukodystrophy.

PTP4A2 is part of a small class of the protein tyrosine phosphatase (PTP) family. PTP4A2 is localized to the early endosome that take part in a variety of cellular activities. PTP4A2 protein interacts with the beta-subunit of Rab geranylgeranyltransferase II (beta GGT II), therefore has a role as a regulator of GGT II activity. Overexpression of PTP4A2 in mammalian cells conferred a transformed phenotype, which suggested its role in tumorigenesis.

Mediator Complex Subunit 21 (MED21) belongs to the mediator complex subunit 21 family. MED21 interacts with the human RNA polymerase II holoenzyme and is participated in transcriptional regulation of RNA polymerase II transcribed genes. A pseudogene of MED21 can be found on chromosome 8. Alternative splicing results in multiple transcript variants.

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.

Lipopolysaccharides (LPS) are a type of glycolipids on the outer cell wall of Gram-negative bacteria. Lipopolysaccharide binding protein (aka LBP) is a plasma protein which facilitates the diffusion of bacterial LPS (endotoxin). LBP is involved in the acute-phase immunologic response to gram-negative bacterial infections. In cooperation with bactericidal permeability-increasing protein (BPI), LBP binds LPS and interacts with the CD14 receptor, most likely playing a role in regulating LPS-dependent monocyte responses. LBP belongs to a family of structurally and functionally related proteins, including BPI, plasma cholesteryl ester transfer protein (CETP), and phospholipid transfer protein (PLTP). The LBP gene is found on chromosome 20, directly downstream of the BPI gene. LBP catalyzes the transfer of LPS monomers from LPS aggregates to HDL particles, to phospholipid bilayers, and to a binding site on soluble CD14 (sCD14). sCD14 is capable of speeding up the transfer by receiving an LPS monomer from an LPS aggregate, and then yielding it to an HDL particle, therefore acting as a soluble "shuttle" for an insoluble lipid.

West Nile virus (WNV) is a virus of the family Flaviviridae part of the Japanese encephalitis (JE) antigenic complex of viruses. Image reconstructions and cryoelectron microscopyreveal a 45-50 nm virion covered with a relatively smooth proteinsurface. This structure is similar to virus; both belong to the genus flavivirus within the family Flaviviridae. WNV is a positive-sense, single strand of RNA, it is between 11,000 and 12,000 nucleotides long which encode seven non-structural proteins and three structural proteins. The RNA strand is held within a nucleocapsid formed from 12 kDaprotein blocks; the capsid is contained within a host-derived membrane altered by two viral glycoproteins.

GH-releasing peptides (GHRPs) are synthetic peptides that like GHRH effect on pituitary somatotrophs to stimulate GH release. The GHRP5 is one of several synthetic met-enkephalin analogs that owns unnatural D-amino acids. They were developed for their growth hormone (GH) releasing activity and called GH secretatogues. They lack opioid activity but are potent stimulators of GH release. These secretatogues are distinct from the growth hormone releasing hormone (GHRH or GHRF) as they share no sequence relation and derive their function through action at a completely different receptor, the ghrelin receptor.

DNA repair protein complementing XP-A cells, (XPA), is a member of the XPA family. XPA protein takes a part in DNA excision repair. It Inductees repair by binding to damaged sites with different affinities depending on the photoproduct and the transcriptional state of the region. Defects in XPA is the reason of xeroderma pigmentosum complementation group A (XP-A), which is infrequent human autosomal recessive disease which characterized by solar sensitivity, high predisposition for developing cancers on areas exposed to sunlight, also may cause to neurological abnormalities.

The NOP16 protein is transcriptionally regulated by c-Myc and upregulated in breast cancer. NOP16 overexpression is linked with poor patient survival.

SNRPE facilitates the cytoplasmic construction of the UsnRNPs by binding to a conserved Sm site on UsnRNA and forming a stable snRNP core complex. While a core protein to UsnRNP, the SNRPE connects with the entire U family of snRNAs including U1–U6. In addition, SNRPE interacts with DDX20 and Small nuclear ribonucleoprotein polypeptide F.

Mitogen-Activated Protein Kinase 6 (MAP2K6) is a part of the dual specificity protein kinase family. MAP2K6 phosphorylates and activates p38 MAP kinase in response to inflammatory cytokines or environmental stress. MAP2K6 is a vital component of the MAP kinase signal transduction pathway. MAP2K6 takes part in various cellular processes such as stress induced cell cycle arrest and apoptosis.

Tp0453 is a carrier of lipids and glycolipids during outer membrane. Tp045 is hypothesized to be a new type of bacterial outer membrane protein, which reduces T.pallidum outer membrane permeability to nutrients while remaining inaccessible to antibodies. Tp0453 exhibited 100% specificity and sensitivity in reaction with syphilis patients’ sera, giving negative result with Lyme disease, relapsing-fever or leptospirosis patients’ sera.

Crystallin, Mu (CRYM) is a taxon-specific crystallin protein which binds NADPH and has sequence similarity to bacterial ornithine cyclodeaminases. CRYM doesn’t perform a structural role in lens tissue; instead CRYM binds thyroid hormone for possible regulatory or developmental roles. CRYM gene mutations are linked with autosomal dominant non-syndromic deafness. CRYM specifically catalyzes the reduction of imine bonds in brain substrates which may include cystathionine ketamine and lanthionine ketamine.

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.

HMGB2 belongs to the non-histone chromosomal high-mobility group protein family which are chromatin-associated and highly spread in the nucleus of higher eukaryotic cells. HMGB2 can successfully bend DNA and form DNA circles which indicates that HMGB2 facilitates cooperative interactions between cis-acting proteins by promoting DNA flexibility. Additionally, HMGB2 takes part in the final ligation step in DNA end-joining processes of DNA double-strand breaks repair and V(D)J recombination.

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.

SKP is a 17kDa trimeric periplasmic chaperone that supports outer membrane proteins in their folding and insertion into membranes. SKP protein is necessary for the normal release of ompA from the inner membrane, the maintenance of its solubility in the periplasm, and, in association with lipopolysaccharide (LPS), for the efficient folding and insertion of ompA into the outer membrane.

Nipsnap Homolog 1 (NIPSNAP1) belongs to the NipSnap family. NIPSNAP1 may take part in vesicular transport. A similar protein in mice inhibits the calcium channel TRPV6, and it is localized to the inner mitochondrialmembrane as well, where it may be involved in mitochondrial DNA maintenance. A pseudogene of NIPSNAP1 is located onthe short arm of chromosome 17. Among the diseases associated with NIPSNAP1 are maple syrup urine disease, and phenylketonuria.

SNRPF is a member of the snRNP Sm proteins family. There are at least seven isoforms, E, F, G, D1, D2, D3 and B/B. This type of common proteins have a crucial part in the biogenesis of the snRNPs. Moreover, they represent the major targets for the so-called anti-Sm auto-antibodies that are diagnostic for systemic lupus erythematosus (SLE). SNRPF assist in the cytoplasmic construction of the UsnRNPs by binding to aconserved Sm site on UsnRNA and forming a stable snRNP core complex.