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Osteocrin is a recently identified secreted protein expression of which was only detected in bone, peaking just after birth and decreasing markedly with age. A 1280-bp mRNA encodes osteocrin producing a mature protein of 103 amino acids with a molecular mass of 11.4 kDa. In primary osteoblastic cell cultures osteocrin expression coincided with matrix formation then decreased in very mature cultures. Treatment of cultures with 1,25-dihydroxyvitamin D3 resulted in a rapid dose- dependent down-regulation of osteocrin expression, suggesting direct regulation. Chronic treatment of primary cultures with osteocrin-conditioned media inhibited mineralization and reduced osteocalcin and alkaline phosphatase expression. These results suggest that osteocrin represents a novel, unique vitamin D-regulated bone-specific protein that appears to act as a soluble osteoblast regulator.

Calreticulin 3 (CALR3) belongs to the calreticulin (CRT) family which consists of calcium binding chaperones that are localized to the endoplasmic reticulum or sarcoplasmic reticulum in eukaryotes. CALR3, which is expressed mainly in testis, takes part in protein-folding, oligomeric assembly and quality control in the ER. CALR3 plays an important role as a cancer-testis antigen due to its frequent expression in many cancers.

Furin is a member of the peptidase S8 family. Furin signifies the ubiquitous endoprotease activity within constitutive secretory pathwaysas well as capable of cleavage at the RX (K/R) R consensus motif.Furin is considered to be one of the proteases responsible for the activation of HIV envelope glycoproteins gp160 as well as gp140 and might take part in tumor progression. Among the diseases associated with FURIN are dementia, familial british and plague.

Kallikreins are a subgroup of serine proteases having various physiological functions. Numerous kallikreins are involved in carcinogenesis. Kallikrein-11 (KLK11) which is a multifunctional protease is 1 of the 15 kallikrein subfamily members found in a cluster on chromosome 19. KLK11 cleaves synthetic peptides after arginine but not lysine residues.

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.

Prorelaxin H2 (RLN2) is a member of a family which is produced by the ovary, targets the mammalian reproductive system to ripen the cervix, elongate the pubic symphysis and inhibit uterine contraction. It may also have other roles in boosting sperm motility, regulating blood pressure, controlling heart rate and releasing vasopressin. RLN2 is a peptide hormone linked to several therapeutically relevant physiological effects, including regulation of collagen metabolism and multiple vascular control pathways. The active form of the RLN2 protein consists of an A chain and a B chain linked by disulfide bonds.

CFD is an important component of the alternative pathway of complement activation. CFD cleaves and activates factor B when it binds C3b or a C3b-like protein such as C3 or CVF. CFD is a serine protease that exists as a mature protease, but it exhibits a highly restricted specificity and it appears to be substrate activated. CFD cleaves factor B bound to C3b leading to the release of the Ba fragment and leaving the Bb fragment bound to C3b. The C3b,Bb complex is called a C3 or C5 convertase because it converts these proteins to their active forms by cleaving off the small peptides C3a and C5a, respectively.

Kallikrein-3 (KLK3) is a part of the kallikrein-related peptidase family. Kallikreins are a subgroup of serine proteases having various physiological functions. Numerous kallikreins take part in carcinogenesis and some may be prospective cancer and other disease biomarkers. Kallikrein-3 is 1 of the 15 kallikrein subfamily members located in a cluster on chromosome 19 and is a protease present in seminal plasma. KLK3 hydrolyzes semenogelin-1 consequently leading to the liquefaction of the seminal coagulum. KLK3 acts normally in the liquefaction of seminal coagulum, probably by hydrolysis of the high molecular mass seminal vesicle protein. Serum level of the KLK3 protein, called PSA in the clinical setting, is beneficial in the diagnosis and monitoring of prostatic carcinoma.

C1s enzyme (a subunit of the C1 complex) is the activated form of C1s proenzyme which is the first complement component in the classical pathway of complement. C1s proenzyme is an inactive zymogen until C1 is activated. C1 is a non-covalent calcium-dependent complex containing1 C1q, 2 C1r and 2 C1s molecules.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. This activation of C1s proenzyme results in its cleavage into 2 C1s chains of 58,000 and 28,000 Dalton.

Native human C8 is a glycosylated protein consist of 3 polypeptide chains: The alpha chain and the gamma chain are disulfide linkedwhereas, The beta chain is non-covalently bound to the a-g complex. C8 is necessary for formation of the membrane attack complex and is activated by binding on the cell membrane newly-formed C5b,C6,C7 complexes. Each pathway of complement activation generates proteolytic enzyme complexes which bind the target surface. These enzymes cleave a peptide bond in the larger alpha chain of C5 releasing C5a and activating C5b. Although C5b is unstable it remains bound to the activating complex for a few minutes during which it binds a single C6 from the surrounding fluid or it decays and is no longer capable of forming MAC.The C5b,6 complex may also remain connected to the C3/C5 convertase where the binding of a single C7 exposes a membrane-binding region and C5b,6,7 can enter into the bilipid layer of the target cell. Each C5b-7 complex can bind 1 molecule of C8 causing the complex to enter more firmly into the membrane.

Matrix metalloproteinase-2 (MMP-2) is involved in endometrial menstrual breakdown, regulation of vascularization and the inflammatory response. MMP-2 contains a number of distinct domains: a prodomain that is cleaved upon activation; a catalytic domain containing the zinc binding site; a fibronectin like domain believed to have a role in substrate targeting; and a carboxyl terminal (hemopexin like) domain containing 2 N-linked glycosylation. The MMP-2 can degrade an extensive array of substrates including type IV, V, VII and X collagens as well as gelatin type I. In addition, MMP-2 interacts with THBS2, TIMP2, Thrombospondin 1, CCL7 and TIMP4. MMP-2 autocatalytic cleavage in the C-terminal generates the anti-angiogenic peptide, PEX. This process seems to be made possible by binding integrinv/beta3. Defects in the MMP-2 are the cause of Torg-Winchester syndrome (TWS), aka multicentric osteolysis nodulosis and arthropathy (MONA).

C3d is derived from human C3 after a series of proteolytic cleavages.C3d is prepared from purified human C3. The C3 is converted to C3b by treatment with the natural human C3 convertase and this C3b is converted to iC3b. Finally, this iC3b is cleaved with trypsin to yield C3d.If the C3b precursor was attached to a surface (as occurs during complement activation) the iC3b, C3dg and C3d fragments would remain covalently attached to that surface.C3d is able to attach to a surfaceonly during complement activation on a surface. Surface-bound C3d is linked to the target through an ester or an amide covalent bond. Ester bonds are unstable, thusC3d releasesfrom the particle.

Growth/differentiation factors (GDF1-GDF15) belong to the BMP family of TGF-beta superfamily proteins. These factors are produced as inactive preproproteins which are subsequently cleaved and assembled into active secreted homodimers. BMP13 is a growth factor which controls proliferation and cellular differentiation in the retina and bone formation. BMP13 has a central role in regulating apoptosis during retinal development. GDF proteins are vital during embryonic development, particularly in the skeletal, nervous, and muscular systems. BMP13 gene mutations result in colobomata, which are congenital abnormalities in ocular development, and in Klippel-Feil syndrome (KFS), which is a congenital disorder of spinal segmentation.

CRNN is part of the "fused gene" family of proteins, which enclose N-terminus EF-hand domains and multiple tandem peptide repeats. CRNN contains two EF-hand Ca2+ binding domains in its N-terminus and two glutamine- and threonine-rich 60 amino acid repeats in its C-terminus. CRNN, also known as SEP53, which participates in the mucosal/epithelial immune response and epidermal differentiation. CRNN is a survival factor that participates in the clonogenicity of squamous esophageal epithelium cell lines, attenuates deoxycholic acid (DCA)-induced apoptotic cell death and discharge of calcium. When CRNN is over expressed in oral squamous carcinoma cell lines, it regulates negatively cell proliferation by the induction of G1 arrest.

C-type Lectin Domain Family 1 Member B, also known as CLEC1B. NK-Natural killer cells express multiple calcium-dependent (C-type) lectin-like receptors, for instance CD94 (KLRD1; MIM 602894) and NKG2D (KLRC4; MIM 602893), which interact with major histocompatibility complex class I molecules and either inhibit or else activate cytotoxicity and cytokine secretion. CLEC1B is a C-type lectin-like receptor which is expressed in myeloid cells as well as in NK cells.

Ferric Uptake Regulator protein NCBI Accession No.: NP_415209 is a DNA-binding protein which controls iron-responsive genes. Ferric Uptake Regulator has a molecular mass of 17-kDa and plays a role in global transcriptional repressor that in the existence of iron regulates functions as diverse as iron acquisition, oxidative stress, and virulence. In Escherichia coli, members of the Ferric Uptake Regulator family regulate the expression of at least 100 genes that function in processes as diverse as the biosynthesis and transport of siderophores, the expression of virulence factors, the alleviation of oxidative and NO-induced stress, and the inhibition of ferritin production through the expression of RyhB.

Egl Nine Homolog 3 (EGLN3) belongs to the EGLN family of prolyl hydroxylases. EGLN3 catalyzes hydroxylation of the ? subunit of hypoxia-inducible factor-?, which targets hypoxia-inducible factor-? for ubiquitination by a ubiquitin ligase complex containing the von Hippel-Lindau (VHL) tumor suppressor. EGLN3 is the most significant isozyme in limiting physiological activation of HIFs (especially HIF2A) in hypoxia. EGLN3 is activated in cardiovascular cells and Hela cells after exposure to hypoxia. In addition, EGLN3 hydroxylates PKM2 in hypoxia, thus limiting glycolysis. Under normoxia, EGLN3 hydroxylates and regulates the stability of ADRB2. EGLN3 is inhibited by polynitrogen compounds possibly by chelation to Fe2+ ions.

CFI cleaves and inactivates C3b and C4b. CFI is inactive without a cofactor such as the soluble factor H and C4b binding protein. CFI cleaves the alpha-peptide chain of C3b and C4b when these binds1 of the cofactors. This cleavage inactivates all of the complement activating functions of these proteins producing iC3b and iC4b.CFI cleaves the alpha chain of C3b twice and this releases a small fragment called C3f. CFI can cleave iC3b releasing C3c from C3dg in the presence of CR1.C4b is cleaved rapidly at 2 sites separating C4c from C4d.

Decorin (DCN) is a small cellular or pericellular matrix proteoglycan which is closely related in structure to biglycan protein. Decorin is a secreted protein which binds to collagen and fibronectin in extracellular matrix. Decorin appears in different glycoforms, substituted with chondroitin sulfate or dermatan sulfate consistent with the original tissue. DCN contains one attached glycosaminoglycan chain. Decorin influences the rate of fibril formation. Decorin is capable of suppressing the growth of various tumor cell lines. DCN gene defects cause corneal dystrophy. The DCN gene is a candidate gene for Marfan syndrome.

CCNH is part of the cyclin family that is known for its protein abundance through the cell cycle. Cyclins act as regulators of CDK kinases. CCNH forms a complex with CDK7 kinase and ring finger protein MAT1. The kinase complex is able to phosphorylate CDK2 and CDC2 kinases, therefore it functions as a CDK-activating kinase (CAK). CCNH and its kinase collaborator are components of TFIIH, as well as RNA polymerase II protein complexes.

Glycogenin-1 (GYG1) is an enzyme involved in glycogen biosynthesis. GYG1 is the chief enzyme involved in glycogen polymerisation. Glycogenin-1 is vital for the function of self-glucosylates, using an inter-subunit mechanism, to form an oligosaccharide primer which acts as substrate for glycogen synthase. In addition, GYG1 has a role in regulating glycogen metabolism and the achievement of maximal glycogen levels in skeletal muscle. GYG1 mRNA and protein content and activity increase in the muscle during recovery from prolonged and exhaustive exercise. GYG1 is inactivated with glycogen catabolism which concurs with an increase in glycogenin gene expression as exercise and glycogenolysis advance. Glycogenin will remain covalently attached to the reducing end of the glycogen molecule.

C7 is necessary for formation of the membrane attack complex and is activated by bindingat the cell membrane to recently-formed C5b,C6 complexes. Each pathway of complement activation generates proteolytic enzyme complexes which bind the target surface. These enzymes cleave a peptide bond in the larger alpha chain of C5 releasing C5a and activating C5b. Although C5b is unstable it remains bound to the activating complex for a few minutes during which it binds a single C6 from the surrounding fluid or it decays and is no longer capable of forming MAC. The C5b,6 complex may also remain connected to the C3/C5 convertase where the binding of a single C7 exposes a membrane-binding region and C5b,6,7 can enter into the bilipid layer of the target cell.

SKP is a 17kDa trimeric periplasmic chaperone that supports outer membrane proteins in their folding and insertion into membranes. SKP protein is necessary for the normal release of ompA from the inner membrane, the maintenance of its solubility in the periplasm, and, in association with lipopolysaccharide (LPS), for the efficient folding and insertion of ompA into the outer membrane.

Complement Factor B, also known as CFB, encodes complement factor B which is a component of the alternative pathway of complement activation. Factor B circulates in the blood as a single chain polypeptide. Once the alternative pathway is activated it is cleaved by complement factor D yielding the noncatalytic chain Ba and the catalytic subunit Bb. The active subunit Bb is a serine protease which connects with C3b to form the alternative pathway C3 convertase. Also, Bb is involved in the proliferation of preactivated B lymphocytes, while Ba inhibits their proliferation.