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Type 1 cystatins are also called stefins which function as intracellular thiol protease inhibitors. Cystatin-B protein is able to form a dimer stabilized by noncovalent forces, inhibiting papain and cathepsins l, h and b. CSTB protein protects proteases leakage from lysosomes. Mutations in Stefin-B gene cause primary defects in patients with progressive myoclonic epilepsy (EPM1), a degenerative disease of the central nervous system. CSTB is overexpressed & elevated in the serum of HCC patients. Cystatin-B in vivo has a polymeric structure which is sensitive to the redox environment. Cystatin-B inhibits bone resorption by down-regulating intracellular cathepsin K activity despite increased osteoclast survival. Protein and mRNA levels of stefin B are significantly lower in atypical benign meningiomas. Stefins-A & Stefin-B which belong to the type-1 Cystatins, are up-regulated in lung tumours and thus able to counteract harmful tumour-associated proteolytic activity. Human stefin-A & Stefin-B form amyloid fibrils. Copper binding by stefin-B reduces amyloid fibril formation. A number of alternatively spliced CSTB isoforms were recognized in patients with progressive myoclonus epilepsy. Decreased CSTB activity in EPM1 pathogenesis is controled by cathepsins through increased activity of cathepsin-S & cathepsin-L.

CALR is a multifunctional protein that acts as a main Ca(2+)-binding (storage) protein in the lumen of the endoplasmic reticulum. Calreticulin is localized in the nucleus, and participates in transcription regulation. Calreticulin binds to the synthetic peptide KLGFFKR, which is nearly identical to an amino acid sequence in the DNA-binding domain of the superfamily of nuclear receptors. CALR binds to antibodies in specific sera of systemic lupus and Sjogren patients which have anti-Ro/SSA antibodies, it is well conserved among species, and it is positioned in the endoplasmic and sarcoplasmic reticulum where it binds calcium. The amino terminus of CALR interacts with the DNA-binding domain of the glucocorticoid receptor and prevents the receptor from binding to its specific glucocorticoid response element. CALR reduces the binding of androgen receptor to its hormone-responsive DNA element and inhibits androgen receptor and retinoic acid receptor transcriptional activities in vivo, as well as retinoic acid-induced neuronal differentiation. Therefore, CALR acts as a significant modulator of the regulation of gene transcription by nuclear hormone receptors.

The bone morphogenetic proteins (BMPs) are a family of secreted signaling molecules that can induce ectopic bone growth. Many BMPs are part of the transforming growth factor-beta (TGFB) superfamily. BMPs were originally identified by an ability of demineralized bone extract to induce endochondral osteogenesis in vivo in an extraskeletal site. Based on its expression early in embryogenesis, the BMP encoded by this gene has a proposed role in early development. In addition, the fact that this BMP is closely related to BMP5 and BMP7 has lead to speculation of possible bone inductive activity.

RAB3A Interacting Protein Like 1 (RAB3IL1) is a 382 amino acid protein which is a member of the SEC2 family. RAB3IL1 is a guanine nucleotide exchange factor (GEF) for Rab3A. RAB3IL1 competes for interaction with Rab3A and IHPK1 via its coiled coil domain, which doesn’t involve IHPK1 kinase activity.

The centromere is a specialized chromatin domain, present throughout the cell cycle, that acts as a platform on which the transient assembly of the kinetochore occurs during mitosis. All active centromeres are characterized by the presence of long arrays nucleosomes in which CENPA replaces histone H3. CENPM is an additional factor required for centromere assembly.

VEGF-C, also known as Vascular Endothelial Growth Factor Related Protein (VRP), is a recently discovered VEGF growth factor family member that is most closely related to VEGF-D. The rat VEGFC cDNA encodes a pre-pro-protein of 416 amino acids residues.
It is almost identical to the mouse VEGF-C protein. Similar to VEGF-D, VEGF-C has a VEGF homology domain spanning the middle third of the precursor molecule and long N- and C-terminal extensions. In adults, VEGF-C is highly expressed in heart, placenta, ovary and small intestine. Recombinant rat VEGF-C, lacking the N- and C-terminal extensions and containing only the middle VEGF homology domain, forms primarily non-covalently linked dimers. This protein is a ligand for both VEGFR-2/KDR and VEGFR-3/FLT -4. Since VEGFR-3 is strongly expressed in lymphatic endothelial cells, it has been postulated that VEGF-C is involved in the regulation of the growth and/or differentiation of lymphatic endothelium. Although recombinant rat VEGF-C is also a mitogen for vascular endothelial cells, it is much less potent than VEGF-A.

SURF1 plays a role in the biogenesis of the COX complex. SURF1 is found in the inner mitochondrial membrane and takes part in the biogenesis of the cytochrome c oxidase complex. SURF1 is shares a bidirectional promoter with SURF2 on the opposite strand. Defects in this SURF1 cause Leigh syndrome, a rigorous neurological disorder that is generally associated with systemic cytochrome c oxidase deficiency.

LRPAP1 is a member of the alpha-2-MRAP family. LRPAP1 cooperates with LRP1/alpha-2-macroglobulin receptor and glycoprotein 330. LRPAP1, located on the cell surface, creates a complex with the alpha 2 macroglobulin receptor light and heavy chains and has part in the pathogenesis of membrane glomerular nephritis.

Adipocyte fatty acid binding protein FABP4 is a 15 kDa member of the intracellular fatty acid binding protein (FABP) family, which is known for the ability to bind fatty acids and related compounds (bile acids or retinoids) in an internal cavity. FABP4 is expressed in a differentiation-dependent fashion in adipocytes and is a critical gene in the regulation of the biological function of these cells.
In mice, targeted mutations in FABP4 provide significant protection from IR in the context of both dietary and genetic obesity. Adipocytes obtained from FABP4-deficient mice also have reduced efficiency of ipolysis in vitro and in vivo, and these mice exhibited moderately improved systemic dyslipidemia. Recent studies also demonstrated FABP4 expression in macrophages upon differentiation and activation. In these cells, FABP4 modulates inflammatory responses and cholesterol ester accumulation, and total or macrophage-specific FABP4 deficiency confers dramatic protection against atherosclerosis in the apoE-/- mice. These results indicate a central role for FABP4 in the development of major components of the metabolic syndrome through its distinct actions in adipocytes and macrophages.

KRT20 is a member of the keratin family. The keratins are intermediate filament proteins responsible for the structural integrity of epithelial cells and are subdivided into cytokeratins and hair keratins. The type I cytokeratins consist of acidic proteins which are arranged in pairs of heterotypic keratin chains. This cytokeratin is a major cellular protein of mature enterocytes and goblet cells and is specifically expressed in the gastric and intestinal mucosa. The type I cytokeratin genes are clustered in a region of chromosome 17q12-q21.

Caspase Recruitment Domain Family, Member 17 (CARD17) is a regulator of procaspase-1/CASP1 activation involved in the regulation of the proteolytic maturation of pro-IL-1beta/IL1B and its release throughout inflammation. CARD17 inhibits the release of IL1B in reaction to LPS in monocytes. Though, unlike CASP1, CARD17 do not induce NF-kappa-B activation.

CRIP1 also known as Cysteine-Rich Protein 1is a member to the LIM/double zinc finger protein family, membersof which comprise cysteine- and glycine-rich protein-1, rhombotin-1, rhombotin-2, and rhombotin-3. CRIP1 may beimplicated in zinc absorption and also may function as an intracellular zinc transport protein. Among the diseases associated with CRIP1 are situs inversus, and osteosarcoma.

KRT18 encodes the type I intermediate filament chain keratin 18. Keratin 18, together with its filament partner keratin 8, are perhaps the most commonly found members of the intermediate filament gene family. They are expressed in single layer epithelial tissues of the body. Mutations in this gene have been linked to cryptogenic cirrhosis. Two transcript variants encoding the same protein have been found for this gene.

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.

The Sec61 complex is the key component of the protein translocation apparatus of the ER (endoplasmic reticulum) membrane. Oligomers of the Sec61 complex construct a transmembrane channel where proteins are translocated across and incorporated into the ER membrane. This complex consists of 3 membrane proteins- alpha, beta, and gamma. The SEC61B gene encodes the beta-subunit protein. The Sec61 subunits are also detected in the post-ER compartment, suggesting that these proteins can get out of the ER and recycle back.

S100A12 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. S100A12 may be involved in specific calcium-dependent signal transduction pathways and its regulatory effect on cytoskeletal components may modulate various neutrophil activities.

ARL11 (ADP-ribosylation factor-like protein 11) belongs to the ARF family of the Ras superfamily of small GTPases which are known to be involved in multiple regulatory pathways altered in human carcinogenesis. ARFs are highly conserved guanine nucleotide binding proteins which enhance the ADP-ribosyltransferase activity of choleratoxin. ARFs are important in eukaryotic vesicular trafficking pathways and they have a vital role in the activation of phospholipase D (PC-PLD). ARL11 is assumed to act as a tumor suppressor which may have a role in the regulation of apoptosis.

Transferrin receptor protein 1 (TFRC) is required for iron delivery from transferring to cells. The TFRC protein is a transmembrane glycoprotein comprised of 2 disulfide-linked monomers joined by 2 disulfide bonds. Each monomer will bind one holo-transferrin molecule producing an iron-Tf-TfR complex which enters the cell by endocytosis.

Vimentin expression in human malignant glioma cells depends on cellular density, algorithms of drug delivery and chemo/radio treatment. Vimentin and detyrosinated microtubules provide structural support for the extensive microtentacles observed in detached tumor cells and a mechanism to promote successful metastatic spread. Primary colorectal carcinomas display aberrant expression of vimentin, and have activated Notch and TGFbeta signaling pathways. Vimentin is a strong arterial substrate for transglutaminases. Transglutaminase-mediated vimentin dimerization results in a novel unifying pathway by which vasodilatory and remodeling responses may be regulated. Ablation of vimentin expression inhibits migration and invasion of colon and breast cancer cell lines. Vimentin is the main intermediate filament protein in mesenchymal cells and is therefore of value in the differential diagnosis of undifferentiated neoplasms.

Folate Receptor 1, also known as FOLR1, is a part of the folate receptor family whose members bind folic acid. FOLR1 binds to folate and reduced folic acid derivatives and facilitates transfer of 5-methyltetrahydrofolate and folate analogs into the cells. FOLR1 is either attaches to membranes through a glycosyl-phosphatidylinositol linkage or exists in a soluble form. FOLR1 is also needed for embryonic development and normal cell proliferation.

REG protein was shown to be stimulated during the regeneration of pancreatic islets. Since then, many Reg-related proteins have been identified in humans and other animals. In human, the four REG family genes, i.e., REG 1 alpha, REG 1 beta, REG-related sequence (RS) and HIP/PAP, have so far been isolated. These Reg-related proteins are classified into four subfamilies according to their amino-acid sequences, but they share a similar structure and physiological function. Reg protein is a growth factor for pancreatic beta cells and also suggests that the administration of Reg protein could be used as another therapeutic approach for diabetes mellitus. Human REG cDNA which encodes a 166-amino acid protein with a 22-amino acid signal peptide. The amino acid sequence of human REG protein has 68% homology to that of rat Reg protein.

CSRP2 belongs to the CSRP family. CSRP2 holds 2 LIM zinc-binding domains that take part in regulatory processes essential for development and cellular differentiation. Additionally, CSRP2 is involved in the development of the embryonic vascular system.

Cysteine-Rich Secretory Protein 2 (CRISP2) regulates some ion channels activity and thereby regulates calcium fluxes during sperm capacitation. Amongst its related pathways are p53 signaling. Diseases related with CRISP2 include epididymitis and orchitis.

The CTX family of proteins (including ASAM) are type I transmembrane proteins within the Ig superfamily, which localize to junctional complexes between endothelial and epithelial cells and may play a role in cell-cell adhesion. CLMP has a role in adipocyte differentiation and development of obesity. CLMP is required for normal small intestine development.