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UL16 Binding Protein 3 (ULBP3) is a ligand for the NKG2D receptor in NK cells. ULBPs activate different signaling pathways resulting in the production of cytokines and chemokines. ULBP3 is a ligand for the KLRK1/NKG2D receptor, along with at least ULBP1 and ULBP2. Binding of ULBPs ligands to KLRK1/NKG2D stimulates calcium mobilization and activation of the JAK2, STAT5, ERK and PI3K kinase/Akt signal transduction pathway. ULBP3 has lower affinity for KLRK1/NKG2D compared to ULBP1 and ULBP2 and stimulates weaker signaling responses than does ULBP2 or ULBP1.

Syntaxin-binding protein 6 (STXBP6) binds components of the SNARE complex and takes part in regulating SNARE complex configuration. STXBP6 forms non-fusogenic complexes with SNAP25 and STX1A and modulates the formation of SNARE complexes and exocytosis.

ULBP1 together with at least ULBP2 and ULBP3, is ligand for the NKG2D receptor. ULBPs stimulate various signaling pathways in primary NK cells, which result in cytokines and chemokines production. In CMV infected cells, ULBP1 cooperates with soluble CMV glycoprotein UL16 to inhibit the interaction with the NKG2D receptor providing a mechanism by which CMV infected cells escape the immune system. Additionally, UL16 retains ULBP1 to the ER and cis-Golgi apparatus to prevent it from reaching cell surface.

The protein encoded by this gene is a member of the bone morphogenetic protein family which is part of the transforming growth factor-beta superfamily. The superfamily includes large families of growth and differentiation factors. Bone morphogenetic proteins were originally identified by an ability of demineralized bone extract to induce endochondral osteogenesis in vivo in an extraskeletal site. This particular family member plays an important role in the onset of endochondral bone formation in humans, and a reduction in expression has been associated with a variety of bone diseases, including the heritable disorder Fibrodysplasia Ossificans Progressiva. Alternative splicing in the 5' untranslated region of this gene has been described and three variants are described, all encoding an identical protein.

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.

Guanine Nucleotide Binding Protein Gamma 13, also known as GNG13 is a member of the G protein gamma family. Heterotrimeric G proteins, which consist of alpha, beta, and gamma subunits, function as signal transducers for the 7-transmembrane-helix G protein-coupled receptors. GNG13 is the gamma subunit which is expressed in taste, retinal, and neuronal tissues and takes a central part in taste transduction.

S100A8 is a part of the S100 family of proteins containing 2 EF-hand calcium-binding motifs. S100 proteins are localized in the cytoplasm and/or nucleus of a broad range of cells, and participate in the regulation of cellular processes such as cell cycle progression and differentiation. S100A8 plays a role in the inhibition of casein kinase and as a cytokine. S100A8 altered expression is related with cystic fibrosis disease. S100A8 is a calcium-binding protein that has antimicrobial activity against bacteria and fungi.S100A8 is crucial for resistance towards invasion by pathogenic bacteria. S100A8 up-regulates transcription of genes that are under the control of NF-kappa-B. S100A8 plays a role in the development of endotoxic shock in response to bacterial lipopolysaccharide. S100A8 endorses tubulin polymerization and promotes phagocyte migration and infiltration of granulocytes at sites of wounding. S100A8 takes part as a pro-inflammatory mediator in acute and chronic inflammation and up-regulates the release of IL8 and cell-surface expression of ICAM1.

Polymerase II Polypeptide F (POLR2F) is the 6th largest subunit of RNA polymerase II, the polymerase responsible for synthesizing messenger RNA in eukaryotes, which is also shared by the other two DNA-directed RNA polymerases. In yeast, POLR2F, in combination with at least 2 other subunits, forms a structure which stabilizes the transcribing polymerase on the DNA template. DNA-dependent RNA polymerases catalyze the transcription of DNA into RNA via the 4 ribonucleoside triphosphates as substrates. Pol II is the principal element of the basal RNA polymerase II transcription apparatus. Pols are comprised of mobile elements which move close to each other. In Pol II, POLR2F/RPB6 is part of the clamp element and along with parts of RPB1 and RPB2 constructs a compartment to which the RPB4-RPB7 subcomplex attaches.

Regulation Of Nuclear Pre-MRNA Domain Containing 1A (RPRD1A) is upregulated in cells overexpressing cyclin-dependent kinase inhibitor p15(INK4b) and may have a part in cell cycle regulation. RPRD1A interacts with phosphorylated C-terminal heptapeptide repeat domain (CTD) of the largest RNA polymerase II subunit POLR2A, and partakes in dephosphorylation of the CTD. RPRD1A May function as a negative regulator of cyclin-D1 (CCND1) and cyclin-E (CCNE1) in the cell cycle.

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.

SAR1B is a small GTPase that functions as a homodimer. GTP-Binding Protein SAR1B (SAR1b) is involved in transport from the endoplasmic reticulum to the Golgi apparatus and also in the selection of the protein cargo and the assembly of the COPII coat complex. The SAR1B protein is activated by the guanine nucleotide exchange factor PREB. SAR1B gene defects are a cause of chylomicron retention disease (CMRD), also known as Anderson disease (ANDD).

S100A6 is a member of the S100 family of proteins containing 2 EF-hand calcium-binding motifs. S100 proteins are localized either in the cytoplasm or the nucleus of a wide range of cells. S100 proteins are involved in the regulation of a number of cellular processes such as cell cycle progression and differentiation. There are at least 13 members in the S100 gene family, which are located as a cluster on chromosome 1q21.
S100A6 may function in stimulation prolactin secretion, and exocytosis. Chromosomal rearrangements and altered expression of the S100A6 gene are implicated in melanoma.

Guanine Nucleotide Binding Protein Gamma Transducing 1, also known as GNGT1 is amember of the G protein gamma family. GNGT1 is implicated in various transmembrane signaling systems as a modulator or transducer. In addition GNGT1 (beta & gamma chains) is required for the GTPase activity, for replacement of GDP by GTP, and for G protein- effector interaction.

Olfactory marker protein (OMP) which is expressed in the cytoplasm of olfactory chemosensory neurons in the nasal neuroepithelium, is associated in a unique way with the mature olfactory receptor neurons in numerous vertebrate species. OMP have a modulatory part in the odor detection/signal transduction cascade ant its expression is a sign of mature vertebrate olfactory receptor neurons (ORNs). OMP is also a potent enhancer of mitosis in fetal olfactory epithelial cells and it promotes an increase in uptake of tritiated thymidine in liver.

CRABP1 is a member of special carrier proteins for members of the vitamin A family. It is believed that CRABP1 has an essential role in retinoic acid-mediated differentiation and proliferation processes. Though, CRABP1 is structurally similar to the cellular retinol-binding proteins, it binds only retinoic acid at specific sites within the nucleus, which may contribute to vitamin A-directed differentiation in epithelial tissue. CRABP1 is constitutively expressed and is thought to have different functions in the cell than the related CRABP2. CRABP1 forms a beta-barrel structure which accommodates hydrophobic ligands in its interior. Loss of CRABP1 function as a result of hypermethylation of its promoter leads to pathogenesis of papillary thyroid carcinoma. Furthermore, frequent methylation-associated silencing of CRABP1 is linked to esophageal squamous-cell carcinoma.

Complement Component 4 Binding Protein, Beta (C4BPB) belongs to a superfamily of proteins composed primarily of tandemly arrayed short consensus repeats of approximately 60 amino acids. C4BPB has a regulatory role in the coagulation system also, mediated via the beta-chain binding of protein S, a vitamin K-dependent protein which functions as a cofactor of activated protein C. A single, unique beta-chain of the C4BPB assembles with 7 identical alpha-chains into the principal isoform of C4BPB, which is a multimeric protein that controls activation of the complement cascade via the classical pathway. C4BPB binds as a cofactor to C3b/C4b inactivator (C3bINA), which subsequently hydrolyzes the complement fragment C4b. In addition, C4BPB accelerates the degradation of the C4bC2a complex (C3 convertase) by detaching the complement fragment C2a. Furthermore, C4BPB interacts with anticoagulant protein S and with serum amyloid P component.

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.

S100 calcium binding protein A5 (S100A5) belongs to the S100 family of proteins containing 2 EF-hand calcium-binding motifs. S100 family members are localized in the cytoplasm and/or nucleus of a wide range of cells, and are involved in the regulation of a number of cellular processes such as cell cycle progression and differentiation. S100A5 has a Ca2+ affinity 20-100 fold higher than the other S100 proteins investigated under identical conditions. Furthermore, S100A5 protein binds Zn2+ and Cu2+, and Cu2+ strongly which harms the binding of Ca2+. S100A5 is expressed in very limited regions of the adult brain.

Guanine nucleotide-binding protein G(z) subunit alpha (GNAZ) belongs to the G protein subfamily which mediates signal transduction in pertussis toxin-insensitive systems. GNAZ has a role in maintaining the ionic balance of perilymphatic and endolymphatic cochlear fluids. G proteins are involved as modulators or transducers in a variety of transmembrane signaling systems.

Sex-hormone-binding globulin (SHBG) is a beta-globulin which specifically binds steroid hormones; it is involved in the transport of sex steroids in plasma. The main site of SHBG synthesis is assumed to be the hepatocytes. The production of SHBG is regulated by androgen/estrogen balance, thyroid hormones, insulin and dietary factors, among others. The concentration of SHBG is a key factor regulating their distribution between protein-bound and free states. SHBG concentration determination is primarily significant in the evaluation of mild disorders of androgen metabolism and it allows detection of women with hirsutism who are likely to react to estrogen therapy. Testosterone/SHBG-ratios correlate well with both measured and calculated values for free testosterone thus aid to distinguish between subjects with excessive androgen activity and normal individuals. SHBG gene polymorphisms are linked with polycystic ovary syndrome and type 2 diabetes mellitus.

Calcium-binding protein 39-like (CAB39L), is analogous to MO25 and located in the serum of virtually half of all patients diagnosed with acute monocytic leukemia. CAB39L plays a role in carcinogenesis. Furthermore, LKB1 activity raises upon the binding of a regulatory complex consisting of the STE20-related adaptor-alpha (STRAD alpha) pseudo kinase and the CAB39L.

FUBP1 is a ssDNA binding protein which stimulates expression of c-myc in undifferentiated cells and activates the far upstream element (FUSE) of c-myc. Regulation of FUSE by FUBP happens by single-strand binding of FUBP to the non-coding strand. FUBP1 performs as an ATP-dependent DNA helicase.

ULBP2 is a member of the MHC class I family. ULBP2 is ligand for the NKG2D receptor, composed with at least ULBP1 and ULBP3. ULBPs promote multiple signaling pathways in primary NK cells, triggering the production of cytokines and chemokines. Binding of ULBPs ligands to NKG2D encourages calcium mobilization and activation of the JAK2, STAT5, ERK and PI3K kinase/Akt signal transduction pathway. In CMV infected cells, ULBP2 cooperates with soluble CMV glycoprotein UL16. This cooperation is blocked with the NKG2D receptor, providing a mechanism in which CMV infected cells can escape the immune system. Additionally, UL16 causes ULBP2 to be held in the ER and cis-Golgi apparatus so that it does not reach the cell surface.