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Calbindins are Ca-binding proteins belonging to the troponin C superfamily. CALB28K/Calbindin1/CALB1 (D28K/Spot35 protein or cholecalcin, rat 261 aa; mouse 261 aa; human 261-aa, chromosome 8q21.3-q22.1) was originally described as 27-kDA induced by vitamin D in the duodenum of chicken. In mammals, it is expressed in the kidney, pancreatic islets, and brain. In brain, its synthesis is independent of vitamin D. CABP28K contains 4 active and 2 inactive EF-hand Ca-binding domains. The gene for CABP28K is clustered in the same region as carbonic anhydrase. The neurons in the brains of patients with Huntington disease are CAB28K depleted. There are two types of CaBPs: the "trigger"- and the "buffer"-CaBPs. The conformation of "trigger" type CaBPs changes upon Ca2+ binding and exposes regions on protein that interact with target molecules, thus altering their activity. The buffer-type CABP are thought to control the intracellular calcium concentration. Calbindin D-28K is found predominantly in subpopulations of central and peripheral nervous system neurons, and in certain epithelial cells involved in Ca2+ transport such as distal tubular cells and cortical collecting tubules of the kidney, and in enteric neuroendocrine cells.

Crystallin, Mu (CRYM) is a taxon-specific crystallin protein which binds NADPH and has sequence similarity to bacterial ornithine cyclodeaminases. CRYM doesn’t perform a structural role in lens tissue; instead CRYM binds thyroid hormone for possible regulatory or developmental roles. CRYM gene mutations are linked with autosomal dominant non-syndromic deafness. CRYM specifically catalyzes the reduction of imine bonds in brain substrates which may include cystathionine ketamine and lanthionine ketamine.

Nucleotide Binding Protein 2, also known as NUBP2 is an adenosine triphosphate (ATP) as well as metal-binding protein which is essential for the assembly of cyotosolic iron-sulfur proteins. NUBP2 performs in a heterotetramer with nucleotide-binding protein 1 (NUBP1). Moreover, alternative splicing results in multiple transcript variants have been found for NUBP2.

DnaK, originally identified for its DNA replication by bacteriophage l in E. coli is the bacterial hsp70 chaperone. This protein is involved in the folding and assembly of newly synthesized polypeptide chains and in preventing the aggregation of stress-denatured proteins.The protein coding region of the substrate binding domain of DnaK (amino acids 385-638) was amplified by PCR and cloned into an E. coli expression vector. The substrate binding domain of DNAK was purified to apparent homogeneity by using conventional column chromatography techniques. Additional amino acid (Met) is attached at N- terminus.

Complement Component 4 Binding Protein, Beta (C4BPB) belongs to a superfamily of proteins composed primarily of tandemly arrayed short consensus repeats of approximately 60 amino acids. C4BPB has a regulatory role in the coagulation system also, mediated via the beta-chain binding of protein S, a vitamin K-dependent protein which functions as a cofactor of activated protein C. A single, unique beta-chain of the C4BPB assembles with 7 identical alpha-chains into the principal isoform of C4BPB, which is a multimeric protein that controls activation of the complement cascade via the classical pathway. C4BPB binds as a cofactor to C3b/C4b inactivator (C3bINA), which subsequently hydrolyzes the complement fragment C4b. In addition, C4BPB accelerates the degradation of the C4bC2a complex (C3 convertase) by detaching the complement fragment C2a. Furthermore, C4BPB interacts with anticoagulant protein S and with serum amyloid P component.

Ring Finger Protein 7, also known as RNF7, is an extremely conserved ring finger protein. RNF7 is a vital subunit of SKP1-cullin/CDC53-F box protein ubiquitin ligases that are a part of the protein degradation machinery important for cell cycle progression and signal transduction. RNF7 is a substrate of casein kinase II (CSNK2A1/CKII) and also interacts with it. The phosphorylation of RNF7 by CSNK2A1 promotes the degradation of IkappaBalpha (CHUK/IKK-alpha/IKBKA) and p27Kip1(CDKN1B).

Retinoic acid receptor alpha (RAR) belongs to the large family of ligand responsive gene regulatory proteins that includes receptors for steroid and thyroid hormones. These proteins contain two highly conserved domains that are involved in determining their DNA and ligand-binding activities. There are three isotypes of RAR proteins: alpha, beta, and gamma. The RAR proteins are encoded by distinct genetic loci and possess distinct transcriptional properties. Typically, RAR-alpha represses target gene transcription in the absence of hormone, whereas RAR-beta and gamma fail to repress under these conditions. RARA is a receptor for retinoic acid that has profound effects on vertebrate development. Retinoic acid is a morphogen and is a powerful teratogen. RARA controls cell function by directly regulating gene expression.
Chromosomal aberrations involving RARA cause acute promyelocytic leukemia (APL).

S100P was originally described as a placental protein of 95 amino acid residues shares about 50% sequence identity with the brain S100 proteins alpha and beta.
S100 proteins are small dimeric members of the EF-hand superfamily of Ca(2+) binding proteins thought to participate in mediating intracellular Ca(2+) signals by binding to and thereby regulating target proteins in a Ca(2+)-dependent manner. S100P in addition to binding Ca2+, also binds Zn2+ and Mg2+. S100P gene is located on chromosome 4p16.
S100P is dysregulated in the androgen-independent prostate cancer cell lines LNCaP-R, DU145, and PC3 and may play a role in the etiology of prostate cancer.
In ductal hyperplasias, in situ and invasive ductal carcinoma, but not in the normal tissues, S100P overexpression is an early event that might play an important role in the immortalization of human breast epithelial cells in vitro and tumor progression in vivo.
In NIH3T3 cells, the expression of S100P led to the presence of S100P in the culture medium, increased cellular proliferation, and enhanced survival following detachment from the culture substrate or after exposure to the chemotherapeutic agent 5-flurouracil. The proliferation and survival effects of S100P expression were duplicated in a time- and concentration-dependent manner by extracellular addition of purified S100P to wild-type NIH3T3 cells and correlated with the activation of Erks and NFB.
To determine the mechanisms involved in these effects, we tested the hypothesis that S100P activated RAGE (Receptor for Activated Glycation End-Products). It was found that S100P coimmunoprecipitated with RAGE. Furthermore, the effects of S100P on cell signaling, proliferation and survival were blocked by agents that interfere with RAGE including administration of an amphoterin derived peptide known to antagonize RAGE activation, anti-RAGE antibodies and by expression of a dominant negative RAGE. These data suggest that S100P can act in an autocrine manner via RAGE to stimulate cell proliferation and survival.

Protein A is a cell wall component produced by several strains of Staphylococcus aureus. The recombinant Protein A is genetically engineered protein and holds 5 IgG-binding regions of protein A. Recombinant Protein A functions basically the same as native Protein A and is perfect for purification of polyclonal or monoclonal IgG antibodies. Protein A binds to human IgG1, IgG2 and IgG4, mouse IgG2a, IgG2b and IgG3 and rat IgG2c. Protein A also binds to total IgG from rabbit, pig, dog, cat, and guinea pig.

PAIP2 has a role as a repressor in the regulation of translation initiation of poly(A)-containing mRNAs. PAIP2 inhibitory activity on translation is mediated through its action on PABPC1. PAIP2 displaces the interaction of PABPC1 with poly(A) RNA and competes with PAIP1 for binding to PABPC1. PAIP2 association with PABPC1 results in disruption of the cytoplasmic poly(A) RNP structure organization.

The La protein is a 47 kDa polypeptide that frequently acts as an autoantigen in systemic lupus erythematosus and Sjogren's syndrome patients. La is involved in various aspects of RNA metabolism, including binding and protecting 3-prime UUU(OH) elements of newly RNA polymerase III - transcribed RNA, processing 5-prime and 3-prime ends of pre-tRNA precursors, acting as an RNA chaperone, and binding viral RNAs linked to hepatitis C virus. It occurs in both the nucleus and the cytoplasm, where it assumes different roles. In the nucleus, La protein facilitates the production of tRNAs, acting as an RNA polymerase III (RNAP III) transcription factor by attaching to the U-rich 3'UTR of nascent transcripts, aiding in their folding and maturation. In the cytoplasm, La protein facilitates the translation of specific mRNAs, acting as a translation factor. As an RNA binding protein (RBP), La protein associates with subsets of mRNAs which contain a 5'-terminal oligopyrimidine (5'TOP) motif known to direct protein synthesis. The binding of La protein to particular classes of RNA molecules regulates their downstream processing, guards them from endonuclease digestion, and organizes their export from the nucleus. La/SS-B appears to be readily disposed to proteolysis, which results in many smaller (42kD, 320, and 270) nevertheless still immunoreactive polypeptides. La/SS-B antigen is strongly conserved across species. Anti-La/SS-B autoantibodies were originally found as precipitating autoantibodies in sera of Sjogren's Syndrome patients and referred to as SjT. Anti-La/SS-B precipitins are most frequently found in Sjogren's Syndrome, Systemic Lupus Erythematosus (SLE) and Subacute Cutaneous Lupus. Also, there seems to be a correlation between anti-La/SS-B and the absence of nephritis in SLE patients.

S100P is a Ca2+ binding protein that is part of the S100 family of proteins containing 2 EF-hand calcium-binding motifs. S100 proteins are found in the cytoplasm and/or nucleus of a large range of cells, and participates in the regulation of a number of cellular function such as cell cycle progression and differentiation. S100P participates in numerous biological functions but the exact functions or mechanism of its action is still mostly unknown. Once S100P binds calcium ions it goes through a conformational change that results in an exposure of a hydrophobic surface which permits the interaction with specific target proteins.

Junctional Adhesion Molecule 2 (JAM2) is a member of the immunoglobulin superfamily, and the junctional adhesion molecule (JAM) family. JAM2 is a type I membrane protein which is localized at the tight junctions of both epithelial and endothelial cells. JAM2 functions as an adhesive ligand for interacting with various immune cell types, and may have a role in lymphocyte homing to secondary lymphoid organs.

Alpha & Gamma-Adaptin Binding Protein (AAGAB), which is also known as P34, takes part in membrane traffic and interacts with AP1G1 and AP2A1.AAGAB is highly expressed in skin and keratinocytes, with the highest levels in adrenal gland, rectum and thymus.

EBAG9 is a type III transmembrane protein that is primarily located in the Golgi. EBAG9 is a tumor-associated antigen that is expressed at high frequency in a variety of cancers, such as advanced breast and prostate cancers. while the EBAG9 acts to inhibit the growth of receptor-binding cells and induced apoptosis of immune cells, cancer cells may evade immune surveillance. Thus immunodetection of EBAG9 expression can be a negative prognostic indicator. EBAG9 promotes progression of bladder cancer. In rheumatoid arthritis, the deficiency of EBAG9 induces CTL infiltration through failure to evade immune attack, therefore leading to apoptosis of the synovial lining cells. EBAG9 is involved in controlling exocytosis processes. EBAG9 expression plays a role in the progression of oral squamous cell carcinoma. EBAG9 plays a specific role in premature stages of breast carcinogenesis.

Dysbindin domain-containing protein 1 (DBNDD1) is a member of the dysbindin family.

RAC1 is a GTPase which belongs to the RAS superfamily of small GTP-binding proteins. Members of this superfamily appear to regulate a diverse array of cellular events, including the control of cell growth, cytoskeletal reorganization, and the activation of protein kinases. RAC-1 regulates the actin cytoskeleton but also other cellular processes. RAC1 have been shown to be involved in the regulation of cell-cell adhesion.

FUBP1 is a ssDNA binding protein which stimulates expression of c-myc in undifferentiated cells and activates the far upstream element (FUSE) of c-myc. Regulation of FUSE by FUBP happens by single-strand binding of FUBP to the non-coding strand. FUBP1 performs as an ATP-dependent DNA helicase.

RRAS2 (RAS viral (r-ras) oncogene homolog 2) is a member of the Ras like GTPase family that cycle between GTP-bound active and GDP-bound inactive states at the cytoplasmic face of the plasma membrane. RRAS2 is a plasma membrane-associated GTP-binding protein with GTPase activity. RRAS2 is implicated in the pathogenesis of human cancers. Hence, overexpression of active RRAS2 in EpH4 cells induces tumorigenicity through the phosphoinositide 3-kinase, p38 MAPK, and mTOR pathways, as these cells lose their sensitivity to the normal growth inhibitory role of TGF-beta. RRAS2 might transduce growth inhibitory signals across the cell membrane, exerting its effect via an effector shared with the Ras proteins but in an antagonistic manner.
RRAS2 is ubiquitously present in all tissues examined, with the highest levels in the heart, placenta, and skeletal muscle. Moderate levels of RRAS2 are found in the lung and liver and low levels in the brain, kidney, and pancreas.
RRAS2 deficiencies are linked to ovarian cancer.

CCAAT/enhancer binding protein(C/EBP) a is a family of transcription factors that all contain a highly conserved, basic-leucine zipper domain at the C-terminus that is involved in dimerization and DNA binding. C/EBP family of transcription factors regulates viral and cellular CCAAT/enhancer element-mediated transcription. C/EBP family consist of several related proteins, C/EBP a,b,g,d, that form homodimers and that form heterodimers with each other. C/EBP proteins contain the bZIP region, which is characterized by two motifs in the C-terminal half of the protein; a basic region involved in DNA binding and a leucine zipper motif involved in dimerization. C/EBPs differ significantly in their physiological functions and in their downstream target genes. For example, mice lacking C/EBPa die shortly after birth due to severe hypoglycemia and the absence of glycogen storage in liver, whereas knockout of C/EBPb causes defects in female reproduction.

Mannose-binding protein C (MBL2),belongs to the collectin family of patternrecognition molecules and is an important component in the innate immune system. MBL2 is a secreted glycoprotein which recognizes mannose and N-acetylglucosamine on various microorganisms, and is capable of activating the classical complement pathway. Lacking MBL2 has been associated with susceptibility to autoimmune and infectious diseases.

ELAV Like Neuron-Specific RNA Binding Protein 2, also known as ELAVL2 is a neural-specific RNA-binding protein which is recognized with his ability to bind to several 3' UTRs, as well as its own and in addition those of FOS and ID. ELAVL2 identify a GAAA motif in the RNA. One of the diseases associated with ELAVL2 is contagious pustular dermatitis.

PQBP1 is a transcription repressor which is connected to polyglutamine tract-containing transcription regulators and connective genes for neurodegenerative disorders. PQBP1 is restricts to the nucleus and can be found in neurons all over the brain, with high levels in hippocampus, olfactory bulb and cerebellar cortex. PQBP1 holds a WWP/WW domain that binds proline-rich motifs and a C2 domain which is able to stimulate Ca2+-dependent phospholipid signaling.