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Serine racemase (SRR) is an enzyme which generates D-serine from L-serine. D-serine functions as a neuronal signaling molecule by activating NMDA receptors in the brain. Mammalian SRR is a pyridoxal 5'-phosphate dependent enzyme which catalyzes both the racemization of L-serine to D-serine and also the elimination of water from L-serine, producing pyruvate and ammonia. The SRR enzyme is physiologically stimulated by divalent cations (e.g., magnesium) and is allosterically activated by the magnesium/ATP complex.

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.

NDUFS4 is a subunit of the mitochondrial membrane respiratory chain NADH dehydrogenase (Complex I), the primary multi-subunit enzyme complex of the mitochondrial respiratory chain. Complex I is involved in cellular ATP production, the main source of energy for numerous vital processes in living cells. NDUFS4 removes electrons from NADH and passes them by a series of diverse protein-coupled redox centers to the electron acceptor ubiquinone. NDUFS4 presents a hotspot of mutations in the genetic apparatus of oxidative phosphorylation and the correct assembly of the subunit it encodes is essential for completion of the assembly of complex I.

Carcinoembryonic antigen (CEA) is a glycoprotein present in fetal digestive-tract tissues; it’s involved in cell adhesion. The production of CEA stops before birth. CEA is called tumor marker since its elevated levels are found in the serum from individuals with colorectal, gastric, pancreatic, lung and breast carcinomas and in heavy smokers.
There are also benign conditions that elevate CEA levels such as smoking, infection, inflammatory bowel disease, pancreatitis, cirrhosis of the liver, and some benign tumors (in the equivalent organs which have cancers with elevated CEA). Typically, higher levels of CEA are found in men, smokers, and older individuals.
The presence of CEA assists in screening, in evaluating recurrent or disseminated disease, and in determining the success of surgical removal of malignant tumors.
CEA levels can be used as indicators of treatment success. The normal values range from 0.0 to 2.5 ng/ml of serum (from blood), in non-smokers, a greater amount than that may be suggestive of cancer. Levels above 20 ng/ml before treatment are associated with cancer which has already metastasized. Benign conditions do not usually cause a CEA increase over 10 ng/ml.
The high levels of CEA should return to normal after successful therapy, however if during follow up there’s an elevation in CEA levels it indicates a recurrence of tumor.
Carcinoembryonic antigen family belongs to the immunoglobulin superfamily; it consists of 29 genes, 18 of which are normally expressed.

Carboxypeptidase A4 (CPA4) belongs to the carboxypeptidase A/B subfamily, and it is located in a cluster with 3 other family members on chromosome 7. CPA4 is a secreted, zinc-dependent metallocarboxypeptidase, which removes the C-terminal amino acid from peptides having a free C-terminal carboxyl group. CPA4 is a metalloprotease which may be involved in the histone hyperacetylation pathway. CPA4 are synthesized as zymogens which are activated by proteolytic cleavage.

NADH Dehydrogenase1 Alpha Subcomplex 4 (NDUFA4) is a member of the complex I 9kDa subunit family. Mammalian complex I of mitochondrial respiratory chain is comprised of 45 different subunits. NDUFA4 protein has NADH dehydrogenase activity and oxidoreductase activity. NDUFA4 transfers electrons from NADH to the respiratory chain. The immediate electron acceptor for the NDUFA4 enzyme is assumed to be ubiquinone.

VPS28 is a subunit of the ESCRT-I complex (endosomal complexes required for transport) involved in the sorting of ubiquitinated proteins. VPS28 is involved in endosomal sorting of cell surface receptors using a multivesicular body/late endosome pathway. VSP28 binding with the TSG101 may have significant roles in budding of Retroviruses, such as HIV-1 and Ebola virus.
VSP28 interacts with TSG101, VPS37B, VPS37C, FAM125A and FAM125B, and also with VPS36, this interaction mediates the association with the ESCRT-II complex. Furthermore it interacts with SNF8 and VPS25 and CEP55.

SHMT1 is a member of the SHMT family. SHMT1 is the cellular form of serine hydroxymethyltransferase, a pyridoxal phosphate-containing enzyme which catalyzes the reversible conversion of serine and tetrahydrofolate to glycine and 5 10-methylene tetrahydrofolate. In addition, SHMT1 specifically provides one-carbon units for thymidylate biosynthesis, reduces methylenetetrahydrofolate pools for S-adenosylmethionine (SAM) synthesis by synthesizing serine, sequesters 5-methyltetrahydrofolate and inhibits SAM synthesis.

Proteasome subunit alpha type 4 (PSMA4) belongs to the peptidase T1A family, which is a 20S core alpha subunit. The proteasome is a multicatalytic proteinase complex with an extremely ordered ring-shaped 20S core structure. The core structure is comprised of 4 rings of 28 non-identical subunits; 2 rings are composed of 7 alpha subunits and 2 rings are composed of 7 beta subunits. PSMA4 is dispersed throughout eukaryotic cells at a high concentration and cleaves peptides in an ATP/ubiquitin-dependent process in a non-lysosomal pathway.

ATF1, a cyclic-AMP dependent transcription factor, is expressed in a large selection of cell types and can dimerize with CREB. MSK1 and MSK2 protein kinases are essential for the stress-induced phosphorylation of transcription factors CREB and ATF1 in primary embryonic fibroblasts. Epidermal growth factor induction of c-jun expression needs ATF1 and MEF2 sites in the c-jun promoter.

Tissue plasminogen activator (abbreviated PLAT or tPA) is a secreted serine proteasewhich converts the proenzymeplasminogento plasmin, a fibrinolyticenzyme. Plasminogen is synthesized as a single chain which is cleaved by PLAT into the two chain disulfide linked plasmin.
This enzyme plays a role in cell migrationand tissue remodeling. Increased enzymatic activity causes hyperfibrinolysis, which manifests as excessive bleeding; decreased activity leads to hypofibrinolysiswhich can result in thrombosisor embolism.

AHCY is an enzyme that catalyzes the reversible hydrolysis of S-adenosylhomocysteine (AdoHcy) to adenosine (Ado) and L-homocysteine (Hcy). AHCY controls the intracellular S-adenosylhomocysteine (SAH) concentration that is crucial for transmethylation reactions. AHCY deficiency causes hypermethioninemia.

Glutamine--Fructose-6-Phosphate Transaminase 1 (GFPT1) participates in the hexosamine pathway and controls the glucose fluidity into the hexosamine pathway. GFPT1 regulates the availability of precursors for N- and O-linked glycosylation of proteins. GFPT1 controls the circadian expression of clock genes ARNTL/BMAL1 and CRY1.

UBE2N belongs to the E2 ubiquitin-conjugating enzyme family. UBE2N catalyzes the ATP-dependent synthesis of non-canonical polyubiquitin chains, a process which doesn’t set in motion proteasomal degradation. UBE2N mediates the transcription of some target genes and is believed to have a role in cell cycle progression; cellular differentiation and DNA repair mechanisms which ensure cell survival after DNA damage.

Mmitochondrial import receptor subunit TOMM20 homolog (TOMM20) is a member of the Tom20 family. The Tom machinery consists of import receptors for the initial binding of cytosolically synthesized preproteins and a general import pore (GIP) for the membrane translocation of various preproteins into the mitochondria. TOMM20 acts as the transit peptide receptor at the surface of the mitochondrion outer membrane and facilitates the movement of preproteins into the TOM40 translocation pore.

NFATC2, also known as nuclear factor of activated T-cells 2, belongs to the nuclear factor of activated T cells family. NFATC2 takes a significant part in the course of T helper cell differentiation, activation, and effector function. Even though KO of an individual NFAT isoform in T cells directs to rather minor effects, T cells lacking for NFATC1 and 2 totally fail to produce T helper cell effector cytokines, for instance the interleukins IL-4 and IL-2. Moreover, NFATC2 is highly phosphorylated and kept in the cytoplasm. Next T cell receptor stimulation, dephosphorylation via calcium-activated calcineurin induces a conformational modification of NFATC2 which reveals a few nuclear localization sequences.

GST family of enzymes comprises a long list of cytosolic, mitochondrial, and microsomal proteins that are 45-55 kDa (dimer form) size and are capable of multiple reactions with a multitude of substrates, both endogenous and xenobiotic. GST catalyses the conjugation of reduced glutathione meaning the sulfhydryl group, to electrophilic centers on a wide variety of substrates. This activity is useful in the detoxification of endogenous compounds such as peroxidised lipids, as well as the metabolism of xenobiotics. GST binds toxins and function as transport protein. Glutathione S-transferase is used to create the so-called 'GST gene fusion system'. The GST is used to purify and detect proteins of interest. In a GST gene fusion system, the GST sequence is incorporated into an expression vector alongside the gene sequence encoding the protein of interest. Induction of protein expression from the vector's multiple cloning sites results in expression of a fusion protein - the protein of interest fused to the GST protein. This GST-fusion protein can then be purified from cells via its high affinity for glutathione. Fusion proteins offer an important biological assay for direct protein-to-protein interactions. The GST tag has the size of 220 amino acids, which, compared to other tags like the myc- or the FLAG-tag, is quite big. It is fused to the N-terminus of a protein. However, many commercially-available sources of GST-tagged plasmids include a thrombin domain for cleavage of the GST tag during protein purification. A GST-tag is often used to separate and purify proteins that contain the GST-fusion. GST-fusion proteins can be produced in Escherichia coli, as recombinant proteins.

Hemoglobin Subunit Zeta (Hbz) or Hba-x is a alpha-like hemoglobin and part of the globin family. The protein is expressed and produced in the the yolk sac in early stages of embryonic development. Hemoglobin subunit zeta has 2 pseudogenes and 5 functional genes.

Short/branched chain specific acyl-CoA dehydrogenase (ACADSB) belongs to the acyl-CoA dehydrogenase family of enzymes which catalyze the dehydrogenation of acyl-CoA derivatives in the metabolism of fatty acids or branch chained amino acids. ACADSB catalyzes the degradation of L-isoleucine while having the highest affinity for (s)-2-methylbutyryl-CoA, isobutyryl-CoA and 2-methylhexanoyl-CoA as substrates. ACADSB may use valproyl-CoA as substrate. ACADSB gene defects cause the short/branched-chain acyl-CoA dehydrogenase deficiency (SBCADD), which is an autosomal recessive disorder characterized by an increase of 2-methylbutyrylglycine and 2-methylbutyrylcarnitine in blood and urine.

GlsA1 is a member of the great superfamily of serine-dependent beta-lactamases and penicillin-binding proteins which exist almost in every bacteria and eukaryotes and catalyze the hydrolytic deamidation of l-glutamine to l-glutamate and free NH4+.

Ubiquitin-conjugating enzyme E2 H (UBE2H) is a member of the ubiquitin-conjugating enzyme family. Protein modification with ubiquitin is a vital cellular apparatus for directing abnormal or short-lived proteins for degradation. Ubiquitination requires at least 3 classes of enzymes: ubiquitin-activating enzymes (E1s) ubiquitin-conjugating enzymes (E2s) and ubiquitin-protein ligases (E3s). UBE2H receives ubiquitin from the E1 complex and catalyzes its covalent attachment to other proteins. UBE2H protein sequence is 100% identical to the mouse homolog and 98% identical to the frog and zebrafish homologs.

SAE1 is part of the ubiquitin-activating E1 family of proteins and participates in the significant first step of the UBL1 conjugation pathway. Proteins conjugated to Ub are marked for progressive degradation by the 26S Proteasome. SAE1 acts as a UBLI E1 ligase mediating the ATP-dependent activation of UBL1. SAE1 binds with UBLE1A and UBLE1B to form a heterodimer which can bind UBL1. SAE1 is a dimeric enzyme that takes part as a E1 ligase for SUMO1, SUMO2, SUMO3, and probably SUMO4. SAE1 regulates ATP-dependent activation of SUMO proteins and formation of a thioester with a conserved cysteine residue on SAE2.