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Connective Tissue Growth Factor is a part of the CCN family of proteins. The CCN family presently consists of six members in human also known as: Cyr61 (Cystein rich 61), CTGF, Nov (Nephroblastoma Overexpressed gene), WISP-1, 2 and 3 (Wnt-1 Induced Secreted Proteins). CCN proteins are matricellular proteins which are involved in the regulation of various cellular functions including: proliferation, differentiation, survival, adhesion and migration. They are expressed in derivatives of the three embryonic sheets and are implicated in the development of kidney, nervous system, muscle, bone marrow, cartilage and bone. During adulthood, they are implicated in wound healing, bone fracture repair, and pathologies such as: tumorigenesis,fibrosis and vascular ailments. Full length secreted CCN proteins can show an antiproliferative activity, whereas truncated isoforms are likely to stimulate proliferation and behave as oncogenes.
The full length protein consists of 4 modules: Module I shares partial identity with the N-terminal part of the Insulin-like Growth Factor Binding Proteins (IGFBPs).
Module II includes a stretch of 70amino acid residues – which shares sequence identity with the Von Willebrand Factor Type C repeat (VWC).
Module III contains sequences sharing identity with the Thrombospondin type 1 repeat (TSP1) (WSXCSXXCG), which is thought to be implicated in the binding of sulfated glycoconjugates and to be important for cell adhesion.
Module IV, also designated CT, is encoded by exon5. It is the leasts conserved one of the four domains at the level of nucleotide sequence, but it appears to be critical for several of the biological functions attributed to the CCN proteins.
Proteolysis of the secreted full-length CCN proteins that has been reported in the case of CCN2 and CCN3 might result in the production of CCN-derived peptides with high affinity for ligands that full-length CNN proteins bind only poorly. Amino-truncated CCN2 isoforms were biologically active whereas no specific biological activity has been attributed to the truncated CCN3. Although the molecular processes underlying the production of these secreted isoforms is presently unknown, it is important to note that proteolysis occur at the same amino acid residues in both CCN2 and CCN3. An elevated expression of CCN2 has also been detected by Northern blotting in human invasive mammary ductal carcinomas, dermatofibromas, pyogenic granuloma, endothelial cells of angiolipomas and angioleiomyomas, and in pancreatic tumors. A study performed with chondrosarcomas representative of various histological grades established that CCN2 expression was closely correlated with increasing levels of malignancy.
In agreement with CCN2 playing a role in brain tumor angiogenesis, immunocytochemistry studies indicated that both glioblastoma tumor cells and proliferating endothelial cells stained positive for CCN2. In astrocytomas, CCN2 expression was particularly elevated in high grade tumors, with a marked effect of CCN2 on cell proliferation. Downregulation of CCN2 expression in these cells was associated with a growth arrest at the G1/S transition while over-expression of CCN2 induced a two-fold increase of the number of cells in the G1 phase. Gene profiling analysis allowed to identify a set of about 50 genes whose expression might account for the proliferative activity of CCN2 in these cells.
CCN2 was seen in a higher proportion of mononuclear cells of patients with acute lymphoblastic leukemia.

CUE Domain Containing 1, also know as CUEDC1 contains 1 CUE domain. The CUE domain is structurally associated to the ubiquitin-binding UBA domain and exists as a domain-swapped dimer which makes additional contacts with ubiquitin, and as a result, binds ubiquitin with higher affinity. The CUE domain is discovered in proteins with diverse functions including protein sorting and degradation of misfolded proteins in the endoplasmic reticulum.

Branched Chain Amino-Acid Transaminase 2 (BCAT2) is a member of the class-IV pyridoxal-phosphate-dependent aminotransferase family. BCAT2 is a branched chain aminotransferase found in mitochondria. BCAT2 forms a dimer which catalyzes the first step in the production of the branched chain amino acids leucine, isoleucine, and valine. In addition, BCAT2 may actn as a transporter of branched chain alpha-keto acids.

Ectonucleoside Triphosphate Diphosphohydrolase 6 or ENTPD6 is an enzyme, akin to E-type nucleotidases. E-type nucleotidases, for instance CD39, are responsible for extracellular nucleotides catabolism. ENTPD6 has four apyrase-conserved areas like all to E-type nucleotidases. Rather spliced transcript agents that codes various isoforms were discovered for the DNA segment.

ERCC1 polypeptide is essential for nucleotide excision repair (NER) of damaged DNA and is homologous to Saccharomyces cerevisiae RAD10, which takes part in repair and mitotic intra-chromosomal recombination. NER mechanism includes dual incisions on both sides of the damage catalyzed by two nucleases. In mammalian cells XPG cleaves 3' of the DNA lesion while the ERCC1-XPF complex makes the 5' incision.

BTC is a potent mitogen for retinal pigment epithelial cells and vascular smooth muscle cells. The effects of betacellulin are mediated by the EGF receptor and other related receptors.

PDCD6 is a calcium-binding protein and is a member of the penta-EF-hand protein family. Calcium binding is vital for homodimerization and for conformational changes essential for binding to other protein partners. PDCD6 takes part in T cell receptor-, Fas-, and glucocorticoid-induced programmed cell death. However, tests showed that in mice deficient for PDCD6, apoptosis was not blocked which suggests that PDCD6 is functionally redundant.

Complement C1q Tumor Necrosis Factor-Related Protein 5 (C1QTNF5) encodes a short-chain collagen which is expressed mainly in sub-retinal pigment epithelium, ciliary epithelium and adipose tissue. C1QTNF5 is increased in mtDNA-depleted myocytes and stimulates the phosphorylation of AMP activated protein kinase. C1QTNF5 takespart in the adhesion of the retinal pigment epithelium (RPE) to the Bruch Membrane. Mutations in C1QTNF5 have been associated with late-onset retinal degeneration.

PKLR is a pyruvate kinase which catalyzes the transphosphorylation of phohsphoenolpyruvate into pyruvate and ATP. That is the rate-limiting step of glycolysis. PKLR gene encodes the L- and R-type isoenzymes through alternate splicing events controlled by different promoters. L-type isoform can also appear as a tetramer and is upregulated by glucose with implications in maturity-onset diabetes of the young.

CD27 belongs to the TNF-receptor superfamily. CD27 is necessary for initiation and long-term maintenance of T cell immunity. CD27 binds to ligand CD70, and has a crucial role in regulating B-cell activation and immunoglobulin synthesis. The CD27 receptor transduces signals which result in the activation of NF-kappaB and MAPK8/JNK. Adaptor proteins TRAF2 and TRAF5 mediate the signaling process of CD27. CD27-binding protein (SIVA), which is a proapoptotic protein, can bind to the CD27 receptor and is believed to have a significant role in the apoptosis induced by CD27.

CD5 antigen-like (CD5L) participates in the regulation of the immune system. CD5L functions as an inhibitor of apoptosis. CD5L is expressed in the spleen, lymph node, thymus and bone marrow.

CD9 which is found on the surface of exosomes is a cell surface glycoprotein which is interacts with integrins and various transmembrane superfamily proteins. CD9 is involved in platelet activation and aggregation and also regulates paranodal junction formation. CD9 takes part in cell adhesion and migration and also promotes muscle cell fusion. CD9 is necessary for the egg-sperm fusion during mammalian fertilization.

Cyclin-dependent kinase 1 (CDK1) plays a significant part in the control of the eukaryotic cell cycle through modulating the centrosome cycle in addition to mitotic onset; CDK1 promotes G2-M transition and regulates G1 progress and G1-S transition using association with multiple interphase cyclins. CDK1 is essential in higher cells for the entry into S-phase and mitosis.

TXNRD1 belongs to the selenium-containing pyridine nucleotide-disulphide oxidoreductase family, which has a conserved catalytic site of Cys-Val-Asn-Val-Gly-Cys. TXNRD1 decreases thioredoxins as well as other substrates, and participates in selenium metabolism and protection against oxidative stress. Inhibition of TXNRD1 activity serves as a potential treatment for cancer, AIDS and other autoimmune diseases as well as bacterial infections and parasitic diseases.

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.

P85a functions as the regulatory subunit of the class IA PI3-kinase isoforms a, b, and d.
It contains two SH2 domains that bind to tyrosine-phosphorylated growth factor receptors or substrate adaptor proteins.
It also contains a BH (breakpoint cluster region homology) domain that shows GAP activity towards the small GTPases Rab4, Rab5, Cdc42, Rac1 and to a lesser extend towards Rab6 and Rab11.
It was shown that PI3Ka catalytic subunit mediated phosphorylation of the p85a adapter reduces the lipid kinase activity of the heterodimer and this gives hints for PI3K-dependent signaling events not requiring production of 3’-phosphorylated phosphoinositides.
PI3Ka protein kinase activity has been implicated in IRS-1 serine phosphorylation in insulin-treated adipocytes and in STAT3 and IRS-1 phosphorylation upon activation of the type 1 IFN receptor by IFN-a.

HD Domain Containing 2, also known as HDDC2 is a member of the HDDC2 family. HDDC2 is an enzyme which contains one HD domain and it is expected to exhibit phosphohydrolase activity. It has been proposed that HDDC2 takes part in nucleic acid metabolism, signal transduction and possibly other functions in bacteria, archaea and eukaryotes. The HD domain consists of highly conserved residues, in particular histidines or aspartates. Porphyria cutanea tarda, Parkinson’s disease and Stickler syndrome have all been related with HDDC2.

Short chain dehydrogenase/reductase family 16C, member5 (SDR16C5) is active in the oxidative direction as well as in the reductive one. SDR16C5 oxidizes all-trans-retinol in all-trans-retinaldehyde. No activity was detected with 11-cis-retinol or 11-cis-retinaldehyde as substrates with either NAD+/NADH or NADP+/NADPH.

PDCD6IP is a Class E VPS protein which participates in concentration and sorting of cargo proteins of the multivesicular body or incorporation into intralumenal vesicles that are generated by invagination and scission from the limiting membrane of the endosome. PDCD6IP binds to the phospholipid lysobisphosphatidic acid which is abundant in MVBs internal membranes. The MVB pathway appears to require the sequential function of ESCRT-O, -I,-II and -III complexes. PDCD6IP is an adapter for a subset of ESCRT-III proteins, such as CHMP4, to function at distinct membranes. PDCD6IP is mandatory for completion of cytokinesis. PDCD6IP takes part in HIV-1 virus budding. PDCD6IP replaces TSG101 in its function of supporting HIV-1 release. PDCD6IP takes part in the regulation of both apoptosis and cell proliferation. PDCD6IP is a cytoplasmic protein that cooperates with apoptosis-associated proteins (ALG-2 and PDCD6) and with the endocytosis-regulator CIN85. Overexpression of PDCD6IP and endophilin

TBCA is a tubulin-folding protein which is involved in the early step of the tubulin folding pathway. TBCA is one of four proteins (cofactors A, D, E, and C) implicated in the pathway directing to properly folded beta-tubulin from folding intermediates. Cofactors A and D are thought to be a factor in capturing and stabilizing beta-tubulin in a quasi-native confirmation. TBCA is crucial for cell viability, if reduced it causes a decrease in the amount of soluble tubulin, alterations in microtubules and G1 cell cycle arrest. Cofactor E attaches to the cofactor D-tubulin complex, afterward, interaction with cofactor C triggers the release of tubulin polypeptides that are committed to the native state.

TIE-1 (tyrosine kinase with Ig and EGF homology domains 1) and TIE-2/Tek comprise a receptor tyrosine kinase (RTK) subfamily with unique structural characteristics: two immunoglobulin-like domains flanking three epidermal growth factor (EGF)-like domains and followed by three fibronectin type III-like repeats in the extracellular region and a split tyrosine kinase domain in the cytoplasmic region. These receptors are expressed primarily on endothelial and hematopoietic progenitor cells and play critical roles in angiogenesis, vasculogenesis and hematopoiesis. Human TIE-1 cDNA encodes a 1122 amino acid (aa) residue precursor protein with an 18 residue putative signal peptide, a 726 residue extracellular domain and a 353 residue cytoplasmic domain. Two ligands, angiopoietin-1 (Ang1) and angiopoietin-2 (Ang2), which bind TIE-2 with high-affinity have been identified. Ang2 has been reported to act as an antagonist for Ang1. Mice engineered to overexpress Ang2 or to lack Ang1 or Tie-1 display similar angiogenic defects.

FKBP3 is part of a family of immunosuppressant receptors which inhibit T-cell proliferation by arresting two distinct cytoplasmic signal transmission pathways. FKBP3 accelerates the folding of proteins. FKBP3 is part of the immunophilin protein family, which participates in immunoregulation and fundamental cellular processes concerning protein folding and trafficking. FKBP3 is a cis-trans prolyl isomerase enzyme that binds the immunosuppressants FK506 and rapamycin, as well as histone deacetylases, the transcription factor YY1, casein kinase II, and nucleolin. It has a greater affinity for rapamycin than for FK506 and therefore is a significant protein for immunosuppression by rapamycin.

CD43 is a key sialoglycoprotein located in the surface of T lymphocytes, monocytes, granulocytes, thymocytes and some B lymphocytes. CD43 is a part of a physiologic ligand-receptor complex which participates in T-cell activation. Throughout T-cell activation, CD43 is actively taken out from the T-cell-APC (antigen-presenting cell) contact site, signifying CD43 has a negative regulatory role in adaptive immune response.