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Cystatins are a superfamily of cysteine proteinase inhibitors found in both plants and animals. They comprise a group of proteinase inhibitors, widely distributed in tissues and body fluids, and form tight complexes with cysteine proteases such as cathepsin B, H, L and S. Cystatin C, a secreted molecule of this family, is of interest from biochemical, medicine and evolutionary points of view. Cystatin C is increased in patients with malignant diseases, and is related to the insufficiency of renal function and appears to be a better marker than creatinine. On the other hand, low levels of cystatin C involve cause the breakdown of the elastic laminae and subsequently, the atherosclerosis and abdominal aortic aneurysm.

Defensins form a family of microbicidal and cytotoxic peptides made by neutrophils. Members of the defensin family are highly similar in protein sequence. This gene encodes defensin, beta 103A, which has broad spectrum antimicrobial activity and may play an important role in innate epithelial defense.

Prolactin is a neuroendocrine hormone synthesized primarily by the pituitary gland but also a variety of other cell types including the placenta, brain and uterus. Its primary function is to promote and maintain lactation but has also been shown to have a role in breast cancer development, regulation of reproductive function and immunoregulation.

Pyruvate Dehydrogenase Complex, Component X, also known as PDHX, encodes the E3 binding protein subunit of the PDH complex which contains 3 catalytic subunits. PDHX tethers E3 dimers to the E2 core of the pyruvate dehydrogenase complexes of eukaryotes. This specific binding is critical for a functional PDH complex.

Streptolysin-O is a sulfhydryl-activated toxin which causes cytolysis by forming pores in cholesterol containing host membranes. After binding to target membranes, the Streptolysin-O protein undergoes a major conformation change, leading to its insertion in the host membrane and creation of an oligomeric pore complex. Cholesterol may be needed for binding to host membranes, membrane insertion and pore formation. Streptolysin-O can be reversibly inactivated by oxidation.

Streptavidin is a tetrameric protein secreted by Streptomyces avidinii which binds firmly to biotin. Streptavidin is widely used in molecular biology through its unique high affinity for the vitamin biotin. The dissociation constant (Kd) of the biotin-streptavidin complex is about ~10-15 mol/L. The strong affinity recognition of biotin and biotinylated molecules has made streptavidin one of the most important components in diagnostics and laboratory kits. The streptavidin/biotin system has one of the biggest free energies of association of yet observed for noncovalent binding of a protein and small ligand in aqueous solution (K_assoc = 10**14). The complexes are also extremely stable over a wide range of temperature and pH.

Platelet endothelial cell adhesion molecule (PECAM1) induces susceptibility to atherosclerosis. PECAM1 averts phagocyte ingestion of closely apposed viable cells by transmitting detachment signals, and transforms function upon apoptosis, thus promoting tethering of dying cells to phagocytes. The encounter of a viable cell with a phagocyte via the homophilic interaction of PECAM1 on both cell surfaces as a result causing the viable cell's active repulsion from the phagocyte.

Gamma-glutamylaminecyclotransferase (A2LD1) is an enzyme which converts gamma-glutamylamines to free amines and 5-oxoproline. A2LD1 demonstrates high activity toward gamma-glutamyl-epsilon-lysine, derived from the breakdown of fibrin and other proteins cross-linked by transglutaminases. A2LD1 assists in the proteolytic degradation of crosslinked fibrin by breaking down isodipeptide L-gamma-glutamyl-L-epsilon-lysine, which is a byproduct of fibrin degradation. The reaction catalyzed by the A2LD1 produces 5-oxo-L-proline and a free alkylamine.

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.

The Argonaute protein is part of the RISC or RNA-induced silencing complex, as so, the protein has a key part in the slicing processes of RNA. The RNA interference (RNAi) is being held by RISC. Small non-coding RNA fragments bond to the Argonaute proteins, through base pairing, eventually leads to the cleavage of messenger RNA or translation suppression.

Myosin light polypeptide 6 (MYL6) is a hexameric ATPase cellular motor protein. MYL6 is composed of 2 heavy chains, 2 nonphosphorylatable alkali light chains, and 2o phosphorylatable regulatory light chains. MYL6 is a myosin alkali light chain which is expressed in smooth muscle and non-muscle tissues. MYL6 partakes in generating the force for cellular movements, thus having an imperative role in overall cellular function.

ApoA5 is an important regulator of serum triglyceride concentrations. An ApoA5 mouse nock-out model produced an approximately four fold increase in serum triglycerides, whereas a knock-in model human ApoA5 produced 50-70% lower concentrations of mouse serum triglycerides. Furthermore, peroxisome proliferators-activated receptoragonists, which are used clinically to lower serum triglyceride concentrations, cause increased ApoA5 mRNA expression. There is very little known about ApoA5 protein in human serum. Lately, it was established that ApoA5 is present in the human serum and it can be detected by polyclonal antibodies against both the HN2 and COOH termini, but at much lower concentration than other apolipoproteins.

Neudesin Neurotrophic Factor (NENF) is a member of the cytochrome b5 family, MAPR subfamily. NENF contains 1 cytochrome b5 heme-binding domain. NENF exhibits neurotrophic activity and activates phosphorylation of MAPK1/ERK2, MAPK3/ERK1 and AKT1/AKT in primary cultured neurons. NENF doesn’t have mitogenic activity in primary cultured astrocytes. NENF may play a part in neuronal differentiation and may have a transient influence on neural cell proliferation in neural precursor cells. NENF neurotrophic activity is increased by binding to heme. NENF is up-regulated in immortal cells and induced in estrogen receptor positive breast cancer expressing progesterone receptor.

Nescient Helix Loop Helix 2 (NHLH2) belongs to the basic helix-loop-helix (bHLH) transcription factor family. NHLH2 is expressed in developing and adult neuroendocrine tissues for example the pituitary and hypothalamus. NHLH2 can act as a DNA-binding protein and may be involved in the control of cell-type determination, probably in the developing nervous system.

Prohibitin (PHB) is an evolutionarily conserved gene that is ubiquitously expressed and which Mutations have been linked to sporadic breast cancer. PHB is thought to be a negative regulator of cell proliferation and may be a tumor suppressor. Prohibitin is expressed as two transcripts with changeable lengths of 3' untranslated region. The longer transcript is present at higher levels in proliferating tissues and cells, proposing that this longer 3' untranslated region functions as a trans-acting regulatory RNA.

Procalcitonin is a peptide hormone mainly produced by the C cells of the thyroid and certain endocrine cells of the lung. Under normal expression conditions, procalcitonin is immediately cleaved into three specific fragments, an N terminal residue, calcitonin and katacalcin. Levels of unprocessed procalcitonin rise significantly after bacterial infection, trauma or shock.

Procalcitonin is a peptide hormone mainly produced by the C cells of the thyroid and certain endocrine cells of the lung. Under normal expression conditions, procalcitonin is immediately cleaved into three specific fragments, an N terminal residue, calcitonin and katacalcin. Levels of unprocessed procalcitonin rise significantly after bacterial infection, trauma or shock.

TXNL4B is a member of the DIM1 family which has a vital role in pro-mRNA splicing. TXNL4B is required in cell cycle progression for S/G2 transition and interacts with PRPF6 subunit of the spliceosome.

VCAM1 is a member of the Ig superfamily. It is a cell surface sialoglycoprotein expressed by cytokine activated endothelium. VCAM-1 contains 6 or 7 immunoglobulin domains, and is expressed on both large and small vessels only after the endothelial cells are stimulated by cytokines. The protein has a number of functions including the regulation of leukocyte migration, leukocyte endothelial cell adhesion and signal transduction and may play a role in a number of inflammatory diseases (artherosclerosis and rheumatoid arthritis).

Hexarelin stimulates GH secretion. Hexarelin is more resistant to proteolytic degradation than GHRP-6.

SOX2 is a transcription factor that forms a trimeric complex with OCT4 on DNA and controls the expression of a number of genes involved in embryonic development such as YES1, FGF4, UTF1 and ZFP206. SOX4 is important for early embryogenesis and for embryonic stem cell pluripotency.

Actin is a muscle protein localized in the I band of the myofibrils; acting along with myosin, it is responsible for contraction and relaxation of muscle. Each actin protomer binds one molecule of ATP and has one high affinity site for either calcium or magnesium ions, as well as several low affinity sites. Actin exists as a monomer in low salt concentrations, but filaments form rapidly as salt concentration rises, with the consequent hydrolysis of ATP. It occurs in globular (G-actin) and fibrous (F-actin) forms. Actin is found in all eukaryotic cells (except for nematode sperm). Actin is one of the most highly-conserved proteins, differing by no more than 20% in species as diverse as algae and humans. Its other functions include cell motility, cell division and cytokinesis, vesicle and organelle movement, cell signaling, and the establishment and maintenance of cell junctions and cell shape.

AGR2 (Anterior gradient 2 homolog) is the human orthologue of the secreted Xenopus laevis Anterior Gradient protein (XAG-2). This is a small, possibly secreted molecule of yet weakly defined functions that is widely expressed in human tissues. Expression of AGR2 shows a positive correlation with expression of estrogen receptor in breast carcinoma and a negative correlation with expression of EGF receptor.

SEPT6 is a member of the septin family of GTPases and is functionally involved in cytokinesis and conservation of cellular morphology. SEPT6 interact with SEPT2. The genes encoding the mixed-lineage leukemia and SEPT2 breakpoint proteins are associated with one type of pediatric acute myeloid leukemia which is caused by reciprocal translocation between chromosomes 11 and X.