Search results

Fibroblast growth factor 18 (FGF18) is a member of the large FGF family which has at least 23 members. FGF18 is a heparin 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.

FHIT enzyme cleaves adenosine 5'' PPP 5'' A to yield AMP and ADP. FHIT gene includees the regular fragile site FRA3B on chromosome 3. Alterations and deletions of the FHIT gene are highly linked to the genesis and establishment of human tumors of the lung, cervix, breast, colon, stomach and pancreas. In normal cells, FHIT functions as a tumor suppressor and physically relates with ubiquitin conjugating enzyme 9.

GFP is an intermediate filament. GFP and vimentin are linked to the same filament network; they are localized in the same filaments.
mRNAs encoding the glial intermediate filament protein are spatially dispersed in the glial cell cytoplasm close to the location of the glial filaments.

Complement Factor Properdin (CFP) which is a plasma glycoprotein, is a positive regulator of the alternative complement pathway of the innate immune system. CFP binds and stabilizes the C3- and C5-convertase enzyme complexes in a feedback loop that eventually ends with formation of the membrane attack complex and lysis of the target cell. Mutations in CFP lead to 2 forms of properdin deficiency that cause high susceptibility to meningococcal infections.

CACYBP (calcyclin binding protein) participates in calcium-dependent ubiquitination and subsequent proteosomal degradation of target proteins. CACYBP acts as a molecular bridge in ubiquitin E3 complexes. CACYBP is involved in the ubiquitin-mediated degradation of beta-catenin.

EFNB1 is a member of the Eph family. The cell-surface proteins Ephrins split into two groups, ephrin-A and ephrin-B, based on their structure and function and perform as ligands for Eph receptors. The transmembrane EFNB1 proteins have conserved cytoplasmic tyrosine residues that are phosphorylated upon interaction with an EphB receptor. In addition, EFNB1 transduces outside-in signals by C-terminal protein interfaces which influence integrin-mediated cell attachment and migration.

Alpha 1-microglobulin (A1M) is a lipocalin superfamily member (kernal lipocalins). A1M is a low molecular weight protein component of plasma. A1M is distributed in plasma and extravascular compartments of all organs. Alpha-1 Microglobulin is found in mammals, birds, amphibians and fish. The primary sites of A1M synthesis are the liver and the kidney. Around the opening of the lipocalin pocket three lysyl residues are situated; those residues carry yellow-brown modification derived from the binding and degradation of heme and kynurenin (a tryptophan metabolite). A1-Microglobulin’s reductase and dehydrogenase have broad biological substrate specificity properties due to its’ free cysteine side-chain which is located in a flexible loop. Alpha-1-microglobulin is glycosylated by three separate carbohydrate chains: two complex carbohydrates which are N-linked to asparagines at residues 17 and 96, and the other simple carbohydrate which is O-linked to threonine at position 5. The carbohydrates comprise 22% of the total molecular mass of the protein. The glycosylation varies between species. A1M exists in two forms- a free form and complexed to other macromolecules: in humans- complexed to immunoglobulin A (IgA), in rat- complexed to alpha-1-inhibitor-3. Free A1M is exceptionally heterogeneous in charge (therefore also known as protein HC), and is found tightly linked to a chromophore. The free Alpha-1-microglobulin is a monomeric protein composed of one 188 residue polypeptide and contains three cysteines, two of which (residues 75 and 173) form a conserved intra-molecular disulphide link. The chromophoric group is covalently bound to the free cysteine residue at position 34. A1M binds retinol as a major ligand, but this is probably distinct from its covalent chromophore. Half of all human plasma A1M (approximately 0.03mg/ml) forms a 1:1 complex with about 5% of plasma immunoglobulin A. The resulting macromolecular complexes’ molecular weight is 200000, and a plasma concentration of 0.3mg/ml. The complex can exhibit both antibody activity and affect many of the biological actions of free Alpha-1-microglobulin. Alpha-1-microglobulin was first discovered in pathological human urine. It was suggested that A1M might be involved in tissue defense against reactive oxygen species, oxidation by heme and kynurenin. Evidence also suggests that A1M functions in the regulation of the immune system. Other functions include: inhibition of stimulation of cultured lymphocytes by protein antigens; induction of cell division of lymphocytes, a mitogenic effect that can either be enhanced or inhibited by the action of other plasma components; inhibition of neutrophil granulocyte migration in vitro; and inhibition of chemotaxis.
Other functions include inhibition of stimulation of cultured lymphocytes by protein antigens; induction of cell division of lymphocytes, a mitogenic effect that can either be enhanced or inhibited by the action of other plasma components; inhibition of neutrophil granulocyte migration in vitro; and inhibition of chemotaxis.

IGFBP6 plays a role in lipoprotein assembly and dietary cholesterol absorption. in addition to its acyltransferase activity, it may act as a ligase. may provide cholesteryl esters for lipoprotein secretion from hepatocytes and intestinal mucosa.

Platelet-activating factor acetylhydrolase 2 cytoplasmic (PAFAH2) has a marked selectivity for phospholipids with short acyl chains at the sn-2 position. PAFAH2 may share a mutual physiologic function with the plasma-type enzyme.

Granzyme-B (GZMB) is essential for target cell lysis in cell-mediated immune responses. GZMB is related to an activation cascade of caspases responsible for apoptosis execution. GZMB cuts caspase-3, -7, -9 and 10 to activate enzymes mediating apoptosis.

The Fas receptor (CD95) mediates apoptotic signaling by Fas-ligand expressed on the surface of other cells. The Fas-FasL interaction plays an important role in the immune system and lack of this system leads to autoimmunity, indicating that Fas-mediated apoptosis removes self-reactive lymphocytes. Fas signaling is also involved in immune surveillance to remove transformed cells and virus infected cells. Binding of FAS to oligimerized FasL on another cell activates apoptotic signaling through a cytoplasmic domain termed the death domain that interacts with signaling adaptors including FAF, FADD and DAX to activate the caspase proteolytic cascade. Caspase-8 and caspase-10 are first activated, to then cleave and activate downstream caspases, and a variety of cellular substrates that lead to cell death. Caspases cleave nuclear lamins, causing the nucleus to break down and lose its normal structure and another caspase substrate is DFF, inducing cleavage and degradation of the genome. Other caspase substrates are involved in cytoskeletal structure, cell cycle regulation and signaling pathways. Activation of JNK kinase, activation of Jun, and production of ceramide may also play roles in Fas-mediated apoptosis. Activation of fas-mediated apoptosis is opposed by I-FLICE and FAP. Viruses and tumors may escape immune surveillance in part through suppression of fas-mediated apoptosis using similar mechanisms.

ADFP is related with the globule surface membrane material. ADFP is a major constituent of the globule surface. Rise in mRNA levels is one of the initial indications of adipocyte differentiation. Mycobacterium leprae regulates ADFP expression to facilitate the accumulation of lipids within infected macrophages for intracellular survival. ADFP is expressed in lipid droplets of vitamin A-storing hepatic stellate cells and additionally in lipid droplets of steatotic hepatocytes. ADFP expression has a role in clear cell renal carcinoma differentiation. ADFP is a component of the lipid droplets in THP-1 cells.

SDCBP2 has two class II PDZ domains. PDZ domains assist protein-protein interactions by attaching to the cytoplasmic C-terminus of transmembrane proteins, and PDZ-containing proteins mediate cell signaling and the organization of protein complexes. SDCBP2 attaches to phosphatidylinositol 4, 5-bisphosphate (PIP2) and take part in nuclear PIP2 arrangement and cell division.

Apolipoprotein-D is mainly associated with high density lipoproteins in human plasma. Apolipoprotein-D is an atypical apolipoprotein and, based on its primary structure, Apolipoprotein-D is a member of the lipocalin family. Lipocalins adopt a beta-barrel tertiary structure and transport small hydrophobic ligands. Apolipoprotein-D binds cholesterol, progesterone, pregnenolone, bilirubin and arachidonic acid.
Apolipoprotein-D is expressed in numerous tissues having high levels of expression in spleen, testes and brain. Apolipoprotein-D is present at high concentrations in the cyst fluid of women with gross cystic disease of the breast, a condition associated with increased risk of breast cancer. Apolipoprotein-D accumulates in regenerating peripheral nerves and in the cerebrospinal fluid of patients with neurodegenerative conditions, such as Alzheimer's disease. Apolipoprotein-D participates in maintenance and repair within the central and peripheral nervous systems. Apolipoprotein-D is a multi-ligand, multi-functional transporter and transports a ligand from 1 cell to another within an organ, scavenge a ligand within an organ for transport to the blood or could transport a ligand from the circulation to specific cells within a tissue.

Ephrin-B3 (EFNB3) which belongs to the ephrin gene family is essential in brain development as well as in its maintenance. EFNB3 binds to, and induces the collapse of, commissural axons/growth cones in vitro. EFNB3 loosely binds Eph receptors located on bordering cells, leading to contact-dependent bidirectional signaling into neighboring cells. The EPH and EPH-related receptors comprise the largest subfamily of receptor protein-tyrosine kinases and are implicated in mediating developmental events, mostly in the nervous system.

Family with Sequence Similarity 3, Member A (FAM3A) is a member of the FAM3 family along with FAM3B (Pander) protein which induces apoptosis of pancreatic alpha and beta cells. FAM3A is a cytokine-like protein, which is expressed in almost all tissues such as the testis, pancreas, adrenal, placenta, brain, fetal brain, liver, kidney, skeletal muscle and the heart. FAM3A gene expression may be regulated by peroxisome proliferator-activated receptor gamma, and the FAM3A protein might be involved in the regulation of glucose and lipid metabolism. Although the function of the FAM3A protein has been unclear until now, it may act as a defensin against invading fungal microorganisms.

Fibronectin Type III Domain Containing 5 (Irisin) is a newly discovered hormone, secreted into circulation by muscle, which acts on white adipocytes and promotes WAT “browning”. r-Irisin can reduce body weight and cause induction of brown adipocyte in vivo, including a capacity for thermogenic energy expenditure mediated by uncoupling protein 1 (UCP-1). Irisin mature protein is comprised of 110 amino acid residues and two potential glycosylation sites. High levels of Irisin can be found in the heart whereas Very low expression is found in the colon, pancreas and spleen, if any.

GH receptor, also known as GHR is part of the cytokine receptor family. GHR binds 2 receptor molecules and in this manner induces signal transduction through receptor dimerization. Furthermore, at high concentrations, GH performs as an antagonist since there is a large difference in affinities at the respective binding sites. The antagonist action can be enhanced further by reducing binding in the low affinity binding site.

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.

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.

Human Retinol Binding Protein, also known as RBP, is responsible for transporting and binding vitamin A. Human RBP has a binding site for 1 molecule of retinol and circulates in the plasma together with prealbumin as a protein complex. The prealbumin binding prevents greater glomerular losses of the human RBP. Only the retinol-free form of the RBP, which has no affinity for prealbumin, undergoes glomerular filtration unhindered as a result of its low Mw. Human RBP is re-absorbed by the tubular cells and catabolized there.

Alpha crystallins are composed of two gene products ; alpha-A and alpha-B, for acidic and basic, respectively. Alpha crystallins can be induced by heat shock and are members of the small heat shock protein (sHSP also known as the HSP20). They act as molecular chaperones and hold them in in large soluble aggregates. These heterogeneous aggregates consist of 30-40 subunits; the alpha-A and alpha-B subunits have a 3:1 ratio, respectively. Two additional function of a-crystallins are an autokinase activity and participation in the intracellular architecture. Alpha-B is expressed widely in many tissues and organs and occurs in many neurological diseases.