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Streptavidin is a tetrameric protein secreted by Streptomyces avidinii which binds firmly to biotin. Streptavidin is wilyde 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.

Obestatin is a hormone that is produced in the cells lining the stomach and small intestine of several mammals including humans; it drastically reduces appetite in mice and is expected to do the same in humans. Obestatin is a peptide hormone - a relatively small protein. It is encoded by the same gene that also encodes ghrelin, a peptide hormone that increases appetite. The protein produced by that gene breaks into two smaller peptides, ghrelin and obestatin. Ghrelin is an endogenous ligand for the growth hormone secretagogue receptor and is involved in regulating growth hormone release. Ghrelin is derived from a preprohormone called preproghrelin, which also generates a second peptide called obestatin. Ghrelin is an endogenous ligand for the orphan G protein-coupled receptor GPR39 and is involved in satiety and decreased food intake.

C1r enzyme is the activated form of C1r proenzyme which is inactive zymogen until C1 is activated.C1r is a subunit of the C1 complex which is the first complement component in the classical pathway of complement. C1 is a non-covalent calcium-dependent complex containing1 C1q, 2 C1r and 2 C1s molecules.Each C1q bindsthe Fc domains of IgG or IgM by using2 or more of its six arms. The binding of multiple arms to immune complexes causesthe production of 2 proteases that cleave and activate the 2 C1s protease zymogens in the complex by the C1r proteins. The activation of C1r results from cleavage of C1r into 2 fragments of 57,000 and 35,000 Dalton.

CDNF is a member of the ARMET family and acts as a trophic factor for neurons. CDNF inhibits the 6-hydroxy (6-OHDA)-induced degeneration of neurons. When CDNF controlled after 6-OHDA-lesioning, it reestablishes the function and inhibits the degeneration of neurons in substantia nigra. CDNF is universally expressed in neuronal and non-neuronal tissues. The highest levels in the brain are found in the optic nerve and corpus callosum.

GMCSF is a cytokine that controls the production, differentiation, and function of granulocytes and macrophages. The active form of the protein is found extracellularly as a homodimer. This gene has been localized to a cluster of related genes at chromosome region 5q31, which is known to be associated with interstitial deletions in the 5q- syndrome and acute myelogenous leukemia. Other genes in the cluster include those encoding interleukins 4, 5, and 13.
GM-CSF stimulates the growth and differentiation of hematopoietic precursor cells from various lineages, including granulocytes, macrophages, eosinophils and erythrocytes.

Cyclophilin-C belongs to the peptidyl-prolyl cis-trans isomerase (PPIase)) family. PPIases catalyze the cis-trans isomerization of proline imidic peptide bonds in oligopeptides and accelerate the folding of proteins. Like other PPIases, the Cyclophilin-C protein can bind immunosuppressant cyclosporin A.

SCO2 protein is a member of the SCO1/2 family. SCO1 and SCO2 proteins are found on the inner membrane of the mitochondria and takes a vital part copper insertion or transport to the active site of cytochrome c oxidase (COX). Flaws in SCO2 are the reason for deadly infantile cardioencephalomyopathy with cytochrome c oxidase deficiency (FIC) which is characterized by hypertrophic cardiomyopathy, lactic acidosis, and gliosis. Heart and skeletal muscle display declines in cytochrome c oxidase (COX) activity, while liver and fibroblasts show mild COX deficiencies.

SERPINI1 (Neuroserpin) is an inhibitory serpin which is expressed primarily in the central nervous system. Even though the physiological target of SERPINI1 is still vague, amassed evidence suggest that SERPINI1 has an imperative role in controlling proteolytic degradation of extracellular matrix (ECM) during synaptogenesis and the subsequent development of neuronal plasticity. The neuroprotective role of SERPINI1 has been demonstrated in transgenic mice lacking SERPINI1 expression. The deficiency of SERPINI1 in these mice is linked with motor neuron disease characterized by axonal degradation. In humans, defects in SERPINI1, caused by point mutations in the neuroserpin gene, trigger a hereditary disorder known as the familial encephalopathy with neuroserpin inclusion bodies (FENIB).

DnaJ (Hsp40) Homolog, Subfamily C, Member 12 (DNAJC12) belongs to the DnaJ/Hsp40 family. DnaJ/Hsp40 family members are linked with complex assembly, protein folding, and export. DnaJ/Hsp40 proteins are extremely conserved throughout evolution and function as co-chaperones regulating protein folding, transport, translational initiation and gene expression. DnaJC12 has a role in protein folding and export and is believed to be involved in estrogen control and the development of breast cancer. DNAJC12 is expressed at high levels in the brain, heart, and testis, and at reduced levels in the kidney and stomach.

DYNLT3 belongs to a subclass of dynein light chains. The DYNLT3 protein homodimerizes and forms the light chain component of the cytoplasmic dynein motor protein complex. DYNLT3 functions as one of several non-catalytic accessory components of the cytoplasmic dynein 1 complex which are believed to be involved in linking dynein to cargos and to adapter proteins that regulate dynein function. DYNLT3 may also work independently of dynein as a transcriptional modulator. DYNLT3 is required for the effective progression through mitosis.

Sclerostin (SOST) is a secreted glycoprotein with a C-terminal cysteine knot-like (CTCK) domain and sequence similarity to the DAN (differential screening-selected gene aberrative in neuroblastoma) family of bone morphogenetic protein (BMP) antagonists. Sclerostin functions as a negative regulator of bone growth, by inhibiting bone formation. SOST is widely expressed at low levels, with highest levels in the bone, cartilage, kidney, liver, bone marrow and primary osteoblasts differentiated for 21 days. SOST gene defects cause sclerosteosis and bone dysplasia.

The bone morphogenetic protein (BMP) receptors are a family of transmembrane serine/threonine kinases that include the type I receptors BMPR1A and BMPR1B and the type II receptor BMPR2. These receptors are also closely related to the activin receptors, ACVR1 and ACVR2. The ligands of these receptors are members of the TGF-beta superfamily. TGF-betas and activins transduce their signals through the formation of heteromeric complexes with 2 different types of serine (threonine) kinase receptors: type I receptors of about 50-55 kD and type II receptors of about 70-80 kD. Type II receptors bind ligands in the absence of type I receptors, but they require their respective type I receptors for signaling, whereas type I receptors require their respective type II receptors for ligand binding.

C1QTNF7 is a collagen type-IV specific for basement membranes.

PDIA3 is an enzyme that belongs to the endoplasmic reticulum and interacts with lectin chaperones calreticulin and calnexin to modulate folding of newly synthesized glycoproteins. PDIA3 has protein disulfide isomerase activity. Complexes of lectins and PDIA3 mediate protein folding by promoting formation of disulfide bonds in their glycoprotein substrates. PDIA3 is expressed in the lumbar spinal cord from rats submitted to peripheral lesion during neonatal period. PDIA3 interacts with thiazide-sensitive sodium-chloride cotransporter in the kidney and is induced by glucose deprivation. PDIA3 is part of the major histocompatibility complex (MHC) class I peptide-loading complex (TAP1), which is important for formation of the final antigen conformation and export from the endoplasmic reticulum to the cell surface.

Pleckstrin homology-like domain family A member 2 (PHLDA2) is a cytoplasmic protein, which is involved in fetal and placental growth. PHLDA2 is an apoptosis-related protein, which acts as a negative growth regulator and is expressed during normal human development. PHLDA2 is imprinted on placenta, liver and fetal tissues during embryogenesis and is removed once development is complete. The PHLDA2 gene is one of a number of genes in the imprinted gene domain of 11p15.5 which is considered to be an important tumor suppressor gene region. Changes in this region may be linked to the Beckwith-Wiedemann syndrome, Wilms tumor, rhabdomyosarcoma, adrenocortical carcinoma, and lung, ovarian, and breast cancer. PHLDA2 is expressed in placenta (present in all cells of the villous cytotrophoblast) and adult prostate gland. Furthermore, PHLDA2 is expressed in adult brain and neuroblastoma, medullablastoma and glioblastoma cell lines and at low levels in adult liver and lung, and fetal liver.

KIT, also known as KIT Proto-Oncogene Receptor Tyrosine, is a cytokine receptor which is expressed not only in hematopoietic stem cells but likewise in other cell types. KIT binds to receptor tyrosine kinase type III, which is a stem cell factor, also named a "rigid factor" or "c-kit ligand". Once this receptor binds to stem cell factor (SCF), it forms a dimer which activates intrinsic tyrosine kinase activity, which sequentially phosphorylates & activates signaling molecules which breed signals in cells. This receptor protects vascular smooth muscle cells from apoptosis in addition to restoring cardiac function after myocardial infarction.

KPNB1 is a member of the importin beta family. The KPNB1 protein is engaged in nuclear protein import, either by coupling itself with an adapter protein (e.g., importin-alpha subunit which binds to nuclear localization signals (NLS) in cargo substrates), or by functioning autonomously as a nuclear transport receptor (acts as NLS receptor, docking of the importin/substrate complex to the nuclear pore complex).

Tyrosylprotein Sulfotransferase 2 (TPST2) is a member of the protein sulfotransferase family. TPST2 is a widely expressed protein, which catalyzes the O-sulfation of tyrosine residues within acidic regions of proteins. The TPST2 protein is a type II integral membrane protein located in the Golgi body.

Gastrokine-2 (GKN2) is expressed in the gastric mucosa. GKN2 forms a heterodimer with TFF1- disulfide linked. GKN2 interacts with TFF2.

CNDP Dipeptidase 1, also known as CNDP1 is a member of the peptidase M20A family. CNDP1 Mannheim which is the shortest allelic form has been more common in the absence of nephropathy in addition to being associated with lower serum carnosinase levels. Furthermore, Carnosine inhibited the increased production of fibronectin as well as collagen type VI in podocytes and the increased production of TGF-beta in mesangial cells. Diabetic patients with the CNDP1 Mannheim variant are less at risk for nephropathy. In addition, on renal cells carnosine protects against the adverse effects of high glucose levels.

Glycophorins A & B (GYPA &GYPB) are the main sialoglycoproteins of the human erythrocyte membrane which carry the antigenic determinants for the MN and Ss blood groups. Along with the M or N and S or s antigens which normally occur in all populations, approximately 40 related variant phenotypes were identified. These variants comprise all the variants of the Miltenberger complex and some isoforms of Sta, as well as Dantu, Sat, He, Mg, and deletion variants Ena, S-s-U- and Mk. GYPA is significant for the function of SLC4A1 and is necessary for high activity of SLC4A1. GYPA is involved in translocation of SLC4A1 to the plasma membrane. GYPA is also a receptor for: the influenza virus, Plasmodium falciparum erythrocyte-binding antigen 175 (EBA-175); binding of EBA-175 is dependent on sialic acid residues of the O-linked glycans and is also a receptor for Hepatitis A virus (HAV).

Ras-related GTP binding C (RRAGC) is a monomeric guanine nucleotide-binding protein, or G protein. As a result of binding GTP or GDP, small G proteins act as molecular regulators in various cell processes and signaling pathways. RRAGC regulates the organization of the actin cytoskeleton and has an intrinsic GTPase activity. RRAGC is possibly necessary for the amino acid-induced relocalization of mTORC1 to the lysosomes and its succeeding activation by the GTPase RHEB, which is key step in the activation of the TOR signaling cascade by amino acids.

RSU1 is a protein which is involved in the ras signal transduction pathway, growth inhibition, and nerve-growth factor induced differentiation processes, as has been established in mouse and human cell line studies. In mouse, RSU1 was originally isolated based on its ability to inhibit v-Ras transformation. RSU1 oossibly has a role in the Ras signal transduction pathway. RSU1 is also capable of suppressing v-Ras transformation in vitro.

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.