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Carcinoembryonic Antigen-Related Cell Adhesion Molecule 21 (CEACAM21) belongs to the family of carcinoembryonic antigen-related cell adhesion molecules (CEACAMs), which are used by a number of bacterial pathogens to bind and invade host cells. The transmembrane protein guides phagocytosis of several bacterial species which is dependent on the small GTPase Rac. CEACAM21 is assumed to have a central role in controlling human-specific pathogens by the innate immune system.

GrpE , co-chaperone of E.coli, participates actively in the response to hyperosomotic and heat shock by preventing the aggregation of stress-denatured proteins in association with DnaK. This protein is the nucleotide exchange factor for DnaK and may function as a thermosensor. Several rounds of ATP-dependent interactions between DnaJ, DnaK and GrpE are required for fully efficient folding.

Colipase (CLPS) is a protein co-enzyme essential for optimal enzyme activity of pancreatic lipase. CLPS is secreted by the pancreas as an inactive form, procolipase, which is then activated in the intestinal lumen by trypsin. CLPS prevents the inhibitory effect of bile salts on the lipase-catalyzed intraduodenal hydrolysis of dietary long-chain triglycerides. CLPS allows lipase to anchor noncovalently to the surface of lipid micelles, counteracting the destabilizing influence of intestinal bile salts. CLPS binds to the C-terminal, non-catalytic domain of lipase, thus stabilizing an active conformation and significantly increasing the whole hydrophobic binding site.

Calmodulin (CaM) is an intracellular receptor protein for Ca2+-ions. It activates the myosin light chain kinase which is the catalyst of myosin phosphorylation. CaM participates in the activation of enzymes such as cyclic nucleotide- dependent phosphodiesterase, calcineurin, ATPase, Myosin Light Chain Kinases, and CAM kinase.

Polcalcin Aln g 4 (Aln G 4.0101) causes an allergic reaction in humans.

Phl p 7.0101 is a secondary allergen of timothy grass pollen, which is non-glycosylated protein. Grass pollen-sensitized individuals show IgE antibodies in their blood system. Phl p 7.0101 is a calcium binding protein with similar sequence to pollen antigens that exist in different plants, hence, cross-reactions are possible.

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.

a-Synuclein (amino acids 1-140), an acidic neuronal protein of 140 amino acids, is extremely heat-resistant and is natively unfolded with an extended structure primarily composed of random coils. a-synuclein has been suggested to be implicated in the pathogenesis of Parkinson’s disease and related neurodegenerative disorders, and more recently, to be an important regulatory component of vesicular transport in neuronal cells. Moreover, recent studies have shown that a-synuclein has chaperone activity and that this activity is lost upon removing its C-terminal acidic tail (amino acids 96-140).

Brain Abundant Membrane Attached Signal Protein 1 (BASP1) is a membrane bound protein with numerous transient phosphorylation positions and PEST motifs. Preservation of proteins with PEST sequences amongst diverse species supports their functional significance. PEST sequences take place in proteins with high turnover rates. Immunological attributes of this protein are species specific. BASP1 undergoes N-terminal myristoylation.

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.

C3b is derived from native C3 upon cleavage with the alternative pathway C3 convertase and release of C3a. C3b is essential to the function of all 3complement pathways. Initiation of each pathway generates proteolytic enzyme complexes (C3 convertases) which binds the target surface. These enzymes cleave a peptide bond in C3 releasing the anaphylatoxin C3a and activating C3b. Most of the C3b created during complement activation. Surface-bound C3b is needed in all 3 pathways for effective activation of C5 and formation of C5b-9 complexes which lyse the target cell membrane. Surface-bound C3b and its breakdown products iC3b and C3d are identifyid by various receptors on lymphoid and phagocytic cells which use the C3b ligand to stimulate antigen presentation to cells of the adaptive immune system. It results in an expansion of target-specific B-cell and T-cell populations.

CTSW protein belongs to the peptidase C1 family. CTSW is a cysteine proteinase with a detailed role in the regulation and mechanism of T-cell cytolytic activity. The encoded CTSW is linked to the membrane inside the endoplasmic reticulum of natural killer and cytotoxic T-cells. CTSW expression is up-regulated by interleukin-2.

C1q is the first component of the classical pathway of complement activation. C1q along with the enzymatically active components C1r and C1s forms the C1 complex. When C1 binds to immunoglobulins in the form of immune complexes, it leads to activation of C1r and C1s proteases and a further activates the classical pathway of complement. C1q is a glycoprotein that belongs to the collectin family, having a molecular weight of about 410-462 kDa. C1q is a hexamer composed of globular heads attached to collagen-like triple-helix tails. The globular heads of C1q exclusively bind to the CH2 domain of IgG molecules or the CH3 domain of IgM. Each heavy chain of the immunoglobulin molecule contains a single binding site for C1q. Given that C1q must bind to no less than two heavy chains in order to alter its conformation and activate C1r and C1s, its activation follows only after binding to immunoglobulins in the form of immune complexes bound to multivalent antigens. C1q’s main physiological role is in the clearance of immune complexes and apoptotic bodies from the organism. Interruption of this process may lead to development of autoimmunity. Individuals with genetic deficiencies of C1q or other components of the classical pathway are at risk to develop SLE. C1q specifically binds to apoptotic bodies of human keratinocytes, vascular endothelial cells and lymphocytes. Complement components C1q and bound C3 mediate the clearance of apoptotic bodies. Hence, C1q may advance the clearance of autoantigens, avoiding stimulation of the immune system. Nonetheless, an extended exposition of the immune system to the neoepitope exposed on C1q molecules bound to immune complexes or apoptotic bodies could ultimately lead to an autoimmune response against C1q itself and to an altered complement function. C1q deficiency may also lead to disruption of the negative selection of autoreactive B cells. C1q along with other specific recognition proteins bind to the highly conserved lupus antigens (dsDNA and nuclear proteins) and activate the complement system. Autoantibodies against C1q (anti-C1q) are found in a number of autoimmune and infectious diseases like glomerulonephritis (GN) and lupus erythematosus (SLE), these antibodies are significant in clinical practice due to their negative predictive value.

C3 is central to the activation of all 3 pathways of complement activation. Initiation of each pathway generates proteolytic enzyme complexes which binds the target surface. These enzymes cleave a peptide bond in C3 releasing the anaphylatoxin C3a and activating C3b. Most of the C3 activated during complement activation never attaches to the surface due to its thioester reaction with water forming fluid phase C3b which is rapidly inactivated by factors H and I forming iC3b. Surface-bound C3b is necessary in all 3 pathways for efficient activation of C5 and formation of C5b-9 complexes that lyse the target cell membrane.

NEFL or Neurofilament light polypeptide is a protein that is encoded through the NEFL gene. NEFL is correlated to a disease called Charcot–Marie–Tooth. The protein’s light subunit is determined by immunoassays in the plasma and cerebrospinal fluid, if present, it can indicate on axonal damage in neurological diseases. By doing so, NEFL can act as a marker for Huntington's disease, Amyotrophic Lateral Sclerosis and multiple sclerosis.

E-selectin which is also called Endothelial leukocyte adhesion molecule 1, ELAM1, ELAM belongs to a family of divalent cation-dependent carbohydrate-binding glycoproteins or adhesion molecules. Eselectin is expressed on the surface of endothelial cells and mediates the interaction of leukocytes and platelets with endothelial cells during an inflammatory response. E-selectin is present in single copy in the human genome and contains 14 exons spanning about 13 kb of DNA.

SPA17 is a protein present at the cell surface. SPA17 was characterized by its participation in the binding of sperm to the zona pellucida of the oocyte. The central portion of SPA17 has carbohydrate binding motifs and likely takes part in cell-cell adhesion functions such as immune cell migration and metastasis.

Alpha-cardiac actin belongs to the actin family which is comprised of three main groups of actin isoforms, alpha, beta, and gamma. The alpha actins are found in muscle tissues and are a major constituent of the contractile apparatus. Defects in the cardiac actin have been associated with idiopathic dilated cardiomyopathy (IDC) and familial hypertrophic cardiomyopathy (FHC).

Peptidase Inhibitor 3, also referred to PI3, is neutrophil and pancreatic elastase-specific inhibitor of skin. The protein may prevent elastase mediated tissue proteolysis. PI3 has shown inhibition of alpha-4-beta-2/CHRNA2-CHRNB2 nicotinic acetylcholine receptor, a weak inhibition on Kv11.1/KCNH2/ERG1 and on the transient receptor potential cation channel subfamily V member 1.

Kell blood group glycoprotein homolog or KEL, is an enzyme, part of the zinc endopeptidase of the neprilysin (NEP) group of proteins. KEL has a crucial part in the production of the potent bioactive ET-3, which also includes enzymes that are endothelin convertingenzymes (PEX, XCE, DINE &various NEP-like proteins). KEL uses a single disulfide bond to XK, a gated membranal transporter. The Kell antigen system that includes two proteins, is very crucial among blood group systems.

Cadherin 11 (CDH11) belongs to the cadherin superfamily (integral membrane proteins) which mediate calcium-dependent cell-cell adhesion. CDH11 is defined based on lacking a HAV cell adhesion recognition sequence specific to type I cadherins. CDH11 protein’s expression in osteoblastic cell lines, and its upregulation during differentiation, suggests a specific function in bone development and maintenance. CDH11 contributes to the sorting of heterogeneous cell types.

Carcinoembryonic Antigen-Related Cell Adhesion Molecule 1 (CEACAM1) belongs to the carcinoembryonic antigen (CEA) gene family which is a part of the immunoglobulin superfamily. CEACAM1 is a cell adhesion protein which mediates homophilic cell adhesion in a calcium-independent way. CEACAM1 is a surface glycoprotein expressed on various blood cells, epithelial cells, and vascular cells. CEACAM1 functions as coinhibitory receptor in immune response, and plays a role also as an activator during angiogenesis.

Carcinoembryonic Antigen-Related Cell Adhesion Molecule 7 (CEACAM7) is a member of the immunoglobulin superfamily, CEA family. CEACAM7 contains 1 Ig-like C2-type (immunoglobulin-like) domain and 1 Ig-like V-type (immunoglobulin-like) domain. CEACAM7 is intensely down-regulated in colonic adenocarcinomas.

Cell surface glycoprotein MUC18 (MCAM), is an integral membrane glycoprotein which is part of the immunoglobulin superfamily. MCAM is related with a variety of carcinomas such as tumor progression, metastasis and is also implicated in embryonic neural development. In Addition, MCAM takes part in cell adhesion, as well as in cohesion of the endothelial monolayer at the intercellular junctions in vascular tissue.