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CD68 encodes a 110-kD transmembrane glycoprotein that is highly expressed by human monocytes and tissue macrophages. It is a member of the lysosomal/endosomal-associated membrane glycoprotein (LAMP) family. The protein primarily localizes to lysosomes and endosomes with a smaller fraction circulating to the cell surface. It is a type I integral membrane protein with a heavily glycosylated extracellular domain and binds to tissue- and organ-specific lectins or selectins. The protein is also a member of the scavenger receptor family. Scavenger receptors typically function to clear cellular debris, promote phagocytosis, and mediate the recruitment and activation of macrophages. Alternative splicing results in multiple transcripts encoding different isoforms.

Uracil DNA glycosylase (UDG), or uracil-DNA glycosylase 1, is a crucial enzyme found in all life forms, involved in repairing damaged DNA by specifically removing uracil bases that are misincorporated into DNA during replication or deaminated cytosine. In various organisms, UDG goes by different names, such as b2580, JW2564, EC 3.2.2.27, DGU, UNG15, HIGM5, EC 3.2.2, HIGM4, and UNG2. Here, we delve into the E. coli UDG, examining its structure, function, and applications in molecular biology.

Structure: The crystal structure of E. coli UDG has been extensively studied, revealing that it belongs to the uracil DNA glycosylase (UDG) superfamily. The E. coli UDG monomer has 229 amino acids with a molecular weight of 25 kDa. The protein has a beta-sheet-rich structure with an alpha-helix on one side and a groove on the other side that binds to DNA. The active site of E. coli UDG contains a conserved glutamic acid residue that acts as a catalytic base to facilitate the hydrolysis of the N-glycosidic bond between uracil and the sugar phosphate backbone.

Function: E. coli UDG plays a critical role in maintaining the integrity of the genome by preventing the accumulation of mutations that can arise from the incorporation of uracil into DNA. Uracil in DNA can occur spontaneously from the deamination of cytosine or can be incorporated during DNA synthesis when dUTP is used instead of dTTP. Unrepaired uracil bases can lead to DNA damage and genomic instability, possibly resulting in cell death or disease. E. coli UDG specifically recognizes and removes uracil bases from DNA, creating an abasic site that is further processed by other repair enzymes.

VEGF-D belongs to the VEGF/PDGF family of proteins. VEGF-D promotes lymphangiogesis, endothelial cell growth, and regulates vascular permeability. In addition, VEGF-D has an important part in the creation of the venous and lymphatic vascular systems and in the growth and maintenance of differentiated lymphatic endothelium Mature VEGF-D forms a noncovalently linked homodimer, and binds to and activate both VEGFR-2 (flk1) and VEGFR-3 (flt4).

GH-releasing peptides (GHRPs) are synthetic peptides that like GHRH act directly on pituitary somatotrophs to stimulate GH release. GHRP-2, an investigational drug, is one of the most potent members of the GHRP family. It has been shown to be effective in adults via the oral and intranasal as well as the iv route of administration.

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.

IL-17F having an accession number of Q96PD4 is a cytokine that shares sequence similarity with IL17. IL-17F is expressed by activated T cells, and has been shown to stimulate the production of several other cytokines, including IL6, IL8, and CSF2/GM_CSF. IL-17F inhibits the angiogenesis of endothelial cells and induce endothelial cells to produce IL2, TGFB1/TGFB, and monocyte chemoattractant protein-1. IL-17F induces stromal cells to produce proinflammatory and hematopoietic cytokines. Intestinal IL17F gene expression is increased in active CD.
IL-17A & IL-17F alleles influence the susceptibility to and pathophysiological features of ulcerative colitis independently. IL-17F and MIF gene polymorphisms are significantly associated with the development of functional dyspepsia.
The initiation of IL-17F/IL-17R signaling pathway requires the receptor ubiquitination by TRAF6. IL-17F induces expression of IFN-gamma-inducible protein 10 (IP-10) by activating Raf1-mitogen-activated protein kinase 1/2-extracellular-regulated kinase 1/2-p90 ribosomal S6 kinase-cyclic AMP response element-binding protein signaling pathway.

GAPDH is a catalytic enzyme normally known to play a role in glycolysis. GAPDH exists as a tetramer composed of 36-kDa subunits and has a range of intracellular functions. GAPDH catalyzes the reversible reduction of 1,3-bisphosphoglycerate to glyceraldehyde 3-phosphophate in the presence of NADPH. Besides functioning as a glycolytic enzyme in cytoplasm, GAPDH has function in intracellular processes such as membrane fusion, microtubule bundling, phosphotransferase activity, nuclear RNA export, DNA replication and DNA repair. GAPDH catalyzes a vital energy-yielding step in carbohydrate metabolism, the reversible oxidative phosphorylation of glyceraldehyde-3-phosphate in the presence of inorganic phosphate and nicotinamide adenine dinucleotide (NAD). The enzyme exists as a tetramer of identical chains.

Oligonucleotide Binding Fold Containing 1 (OBFC1) is a part of the CST complex, a complex which binds to single-stranded DNA and is essential to defend telomeres from DNA degradation. The CST complex binds single-stranded DNA with high affinity in a sequence-independent way, whereas isolated subunits bind DNA with low affinity by themselves. The role of the CST complex is less specific in DNA metabolism at non-telomeric sites.

PDCD4 is restricted to the nucleus in proliferating cells. Expression of PDCD4 is modulated by cytokines in natural killer and T cells. PDCD4 takes part in apoptosis. PDCD4 is a translation inhibitor targeted for degradation during tumor promotion. PDCD4 promotes colonic neoplastic transformation and tumor invasion. PDCD4 is an important target for microrna R-21 in breast cancer cells. Shortage of PDCD4 expression is associated with colorectal cancer.
PDCD4 is swiftly phosphorylated by S6K1 kinase protein & afterwords degraded by ubiquitin ligase SCF in response to mitogens.
PDCD4 in response to mitogens allows competent protein synthesis & cell growth. PDCD4 is a proapoptotic protein involved in TGF-beta1-induced apoptosis in human HCC cells, and a tumor suppressor in hepatocarcinogenesis. PDCD4 restraines tumor progression in colon carcinoma cells by the novel mechanism of down-regulating MAP4K1 transcription, with consequent inhibition of c-Jun activation and AP-1-dependent transcription.
Overexpression of PDCD4 in carcinoid cells results in inhibition of cell proliferation.

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), and VEGFR-3 (Flt-4). Their expression is almost exclusively restricted to endothelial cells, but VEGFR-1 can also be found on monocytes. All VEGF-receptors have seven immunoglobulin-like extracellular domains, a single transmembrane region and an intracellular split tyrosine kinase domain. VEGFR-2 has a lower affinity for VEGF than the Flt-1 receptor, but a higher signalling activity. Mitogenic activity in endothelial cells is mainly mediated by VEGFR-2 leading to their proliferation. Differential splicing of the flt-1 gene leads to the formation of a secreted, soluble variant of VEGFR-1 (sVEGFR-1). No naturally occurring, secreted forms of VEGFR-2 have so far been reported. The binding of VEGF165 to VEGFR-2 is dependent on heparin.

GLO1 is involved in the catalysis and formation of S-lactoyl-glutathione from methylglyoxal condensation and reduced glutatione. GLO1 is linked to HLA and is localized to 6p21.3-p21.1, between HLA and the centromere. GLO1 enzyme is ubundantly expressed and present in numerous tumor cell lines, in which its concentration is often upregulated ubiquitisly. GLO1 is a major susceptible gene for autism in an ethnic Chinese population from Taiwan. GLO1 might be involved in the pathophysiology of mood disorders. GLO1 plays a role in the pathophysiology of mood disorders. Overexpression of GLO1 is associated with kidney tumor.

Twinfilin (TWF1) is a ubiquitous actin-monomer-binding protein which is composed of two ADF-homology domains. Twinfilin forms a 1:1 complex with ADP-actin-monomers, prevents nucleotide exchange on actin monomers and blocks assembly of the monomer into filaments. TWF1 is composed of 2 ADF/cofilin-like (ADF-H) domains joined by a short linker region and followed by a C-terminal tail of approximately 20 residues. The 2 ADF-H domains are approximately 20% homologous to ADF/cofilin and to each other. TWF1 protein may be an actin monomer-binding protein, and its localization to cortical G-actin-rich structures might be regulated by the small GTPase RAC1.

GOT1 is a pyridoxal phosphate-dependent enzyme which exists in cytoplasmic and mitochondrial forms, GOT1 and GOT2, which participate in amino acid metabolism and the urea and tricarboxylic acid cycles. Both enzymes are homodimeric and show close homology.

Lactoferrin is a glycoprotein that belongs to the transferrin family of iron binding proteins. It is found in human breast milk as well as most epithelial surface secretions including tears, nasogastric, saliva, and bronchial. Lactoferrin binds 2 molecules of iron with very high affinity. Lactoferrin inhibits bacterial growth by withholding iron, its N-terminal region is an antimicrobial peptide. Lactotransferrin acts synergistically with lysozyme to potentiate the activity of both proteins. The multifunctional protein lactoferrin has many physiological possible roles. It is often referred to as an innate defense protein and frequently serves as the first line of defense in protection against pathogens. It has been shown to have the ability to bind iron, it is a natural anti-bacterial, anti-fungal and anti-viral, it is an antioxidant and it also has immunomodulatory properties. It has many beneficial properties, which make it a good candidate for a number of product applications. Considerable research is currently going on to explain the various suggested biological functions of lactoferrin.

GSK3B is a serine-threonine kinase that belongs to the glycogen synthase kinase subfamily. GSK3B is involved in energy metabolism, neuronal cell development, and body pattern formation. Polymorphisms in the GSK3B gene have been implicated in modifying risk of Parkinson disease, and studies in mice show that overexpression of the GSK3B gene may be significant to the pathogenesis of Alzheimer disease.

Upstream Transcription Factor 1 (USF1) belongs to the basic helix-loop-helix leucine zipper family, and functions as a cellular transcription factor. USF1 activates transcription via pyrimidine-rich initiator (Inr) elements and E-box motifs. The USF1 gene has been linked to familial combined hyperlipidemia (FCHL). USF1 is a transcription factor which binds to a symmetrical DNA sequence (E-boxes) (5'-CACGTG-3') found in a various viral and cellular promoters.

PDCD4 is restricted to the nucleus in proliferating cells. Expression of PDCD4 is modulated by cytokines in natural killer and T cells. PDCD4 takes part in apoptosis. PDCD4 is a translation inhibitor targeted for degradation during tumor promotion. PDCD4 promotes colonic neoplastic transformation and tumor invasion. PDCD4 is an important target for microrna R-21 in breast cancer cells. Shortage of PDCD4 expression is associated with colorectal cancer. PDCD4 is swiftly phosphorylated by S6K1 kinase protein & afterwords degraded by ubiquitin ligase SCF in response to mitogens. PDCD4 in response to mitogens allows competent protein synthesis & cell growth. PDCD4 is a proapoptotic protein involved in TGF-beta1-induced apoptosis in human HCC cells, and a tumor suppressor in hepatocarcinogenesis. PDCD4 restraines tumor progression in colon carcinoma cells by the novel mechanism of down-regulating MAP4K1 transcription, with consequent inhibition of c-Jun activation and AP-1-dependent transcri

6PGD is the second dehydrogenase in the pentose phosphate shunt. Pentose is neccesary for nucleic acid biosynthesis. The pentose phosphate cycle is a major source of NADPH 6PGD deficiency is usually asymptomatic, and the inheritance of this disorder is autosomal dominant. PGD deficiency raises the erythrocyte pyruvate kinase levels of activity and decreases glutathione synthetase, resulting in hemolysis.

Glucose-6-phosphate isomerase (GPI) is a part of the GPI family whose members encode multifunctional phosphoglucose isomerase proteins involved in energy pathways. GPI is a dimeric enzyme which catalyzes the reversible isomerization of glucose-6-phosphate and fructose-6-phosphate. Mammalian GPI also functions as a tumor-secreted cytokine and an angiogenic factor (AMF) which stimulates endothelial cell motility. In addition, GPI is a neurotrophic factor (Neuroleukin) for spinal and sensory neurons. GPI performs in different capacities inside and outside the cell. In the cytoplasm, GPI is involved in glycolysis and gluconeogenesis, while outside the cell it acts as a neurotrophic factor for spinal and sensory neurons.
Defects in the GPI gene cause the nonspherocytic hemolytic anemia and a severe enzyme deficiency can be linked to hydrops fetalis, immediate neonatal death and neurological impairment.

Hepatocyte Growth Factor (HGF) is a multifunctional growth factor which regulates both cell growth and cell motility. It exerts a strong mitogenic effect on hepatocytes and primary epithelial cells. HGF synergizes with Interleukin-3 and GM-CSF to stimulate colony formation of hematopoietic progenitor cells in vitro and may, therefore, also modulate hematopoiesis.

ARL4D is a developmentally regulated member of the ADP-ribosylation factor/ARF-like protein (ARF/ARL) family of Ras-related GTPases. Small GTP-binding protein which cycles between an inactive GDP-bound and an active GTP-bound form, and the rate of cycling is regulated by guanine nucleotide exchange factors (GEF) and GTPase-activating proteins (GAP). ARL4D takes part in membrane-associated intracellular trafficking. Mutations in this gene is linked to Bardet-Biedl syndrome (BBS).

Fibroblast growth factor 18 (FGF18) is a member of the large FGF family which has at least 23 members. FGF18 is a binding growth factor with a core 120 amino acid FGF domain which allows for a common tertiary structure. FGFs are expressed in the course of the embryonic development and in restricted adult tissues. FGF-18 is an indispensable regulator of long bone and calvarial development. FGF-18 signals via FGFR 1c, 2c, 3c, and 4.