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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.

F-Box Protein 6, also known as FBXO6, is a part of the F-box protein family which is characterized by a roughly forty amino acid motif, the F-box. The F-box proteins are one of the 4 subunits of the ubiquitin protein ligase complex called SCFs (SKP1-cullin-F-box) that operates in phosphorylation-dependent ubiquitination. The F-box proteins are divided into three categories: Fbws containing WD-40 domains, Fbls containing leucine-rich repeats, and Fbxs containing different protein-protein interaction modules or no recognizable motifs. FBXO6 is a part of the Fbxs category, and its C-terminal area is very similar to that of rat NFB42 (neural F Box 42 kDa) which is involved in the control of the cell cycle.

Smac/Diablo is a proapoptotic protein that increases caspase activation in the cytochrome c/Apaf-1/caspase-9 pathway by its binding to the inhibitor of apoptosis proteins (IAPs) and removing their inhibitory activity. Smac/Diablo is a mitochondrial protein which enters the cytosol when cells go through apoptosis, and it moderates the caspase inhibition of IAPs.
Smac/DIABLO expression is associated with the result of renal cell carcinoma.
Dimeric form of Smac/DIABLO implies that once expressed in the cell the protein has a little probability of dissociation and, thus, loss of function.
Survivin, Smac/DIABLO, & PKC-? play an important part in the inhibition of apoptosis by FGF-2 in human small cell lung cancer cells. Mitochondrial survivin associates with Smac/DIABLO, delaying its release. Decreased expression of Smac protein takes part in ovarian carcinogenesis and chemotherapeutic resistance. Smac/DIABLO plays a role in tumor cells during the pathway of apoptosis induction. SMAC protein is regulated by XIAP and degraded by proteasome. SMAC protein takes part inleukemic cell apoptosis.
Smac is released during stress-induced apoptosis in multiple myeloma cells.

TSG101 is a member of apparently inactive homologs of ubiquitin-conjugating enzymes. TSG101 contains a coiled-coil domain that interacts with stathmin, a cytosolic phosphoprotein implicated in tumorigenesis. TSG101 is involved in cell growth and differentiation and acts as a negative growth regulator. TSG101 in vitro steady-state expression is important for maintenance of genomic stability and cell cycle regulation. TSG101 mutations and alternative splicing occur in high rate in breast cancer and implicate that defects occur during breast cancer tumorigenesis and/or progression. TSG101 is a factor of the ESCRT-I complex, a monitor of vesicular trafficking process. TSG101 binds to ubiquitinated cargo proteins and is needed for the sorting of endocytic ubiquitinated cargos into multivesicular bodies. TSG101 is needed for completion of cytokinesis and is involved in cell growth and differentiation.

The protein encoded by this gene is a member of the bone morphogenetic protein family which is part of the transforming growth factor-beta superfamily. The superfamily includes large families of growth and differentiation factors. Bone morphogenetic proteins were originally identified by an ability of demineralized bone extract to induce endochondral osteogenesis in vivo in an extraskeletal site. This particular family member plays an important role in the onset of endochondral bone formation in humans, and a reduction in expression has been associated with a variety of bone diseases, including the heritable disorder Fibrodysplasia Ossificans Progressiva. Alternative splicing in the 5' untranslated region of this gene has been described and three variants are described, all encoding an identical protein.

Leukocyte-associated immunoglobulin-like receptor 2 (LAIR2) is a secreted, 131 amino acids protein which contains one IglikeC2 type domain, rendering it a member of the Ig superfamily. Even though one is secreted and one is membrane bound, the 2 LAIR proteins are assumed to have evolved from a common gene ancestor and seem to share similar adhesion profiles, suggesting that LAIR2 may compete with LAIR1 for ligand binding. LAIR2 was discovered by its similarity to LAIR1, which is an inhibitory receptor present on mononuclear leukocytes. The LAIR2 gene maps to a region of 19q13.4, dubbed the leukocyte receptor cluster, which contains 29 genes in the immunoglobulin superfamily, including LAIR1. The function of the LAIR2 protein is unknown, though it is assumed to be secreted and may help modulate mucosal tolerance.

KPNA2 belongs to the karyopherin alpha family. KPNA2 has a vital part in the nuclear import of proteins with a conventional nuclear localization signal (NLS).
In vitro, KPNA2 bound specifically and directly to substrates having a simple or bipartite NLS motif. KPNA2 stimulated docking of import substrates to the nuclear envelope and together with Ran reconstituted complete nuclear protein import.

PDCD1 is a cell surface membrane protein of the immunoglobulin superfamily. PDCD1 is expressed in pro-B-cells and is thought to have a role in their differentiation. In mice, expression of PDCD1 gene is induced in the thymus when anti-CD3 antibodies are injected and large numbers of thymocytes undergo apoptosis. Mice deficient for the PDCD1 gene bred on a BALB/c background developed dilated cardiomyopathy and died from congestive heart failure. These studies suggest that the PDCD1 gene product may also be important in T cell function and contribute to the prevention of autoimmune diseases.

Non-homologous end-joining factor 1 (NHEJ1) is a member of the XLF family. NHEJ1 is a DNA repair factor vital for the nonhomologous end-joining pathway, which preferentially mediates repair of double-stranded breaks. NHEJ1 gene mutations cause different kinds of severe combined immunodeficiency disorders. NHEJ1 was initially detected as the protein mutated in five patients with growth retardation, microcephaly, and immunodeficiency. In addition, patients with NHEJ1 mutations have immunodeficiency caused by a defect in V(D)J recombination, which employs NHEJ to promote immune system diversity.

PBX/Knotted 1 Homeobox 1 (PKNOX1) is a DNA-binding factor which takes part in the regulation of the transcriptional activity of AP-1 containing promoters. PKNOX1, which is also known as UEF3, PRP-1 and p64, is a Hmeobox protein. PKNOX1 forms stable complexes containing PBX proteins which synergize with AP-1 binding factors.

PRMT1 Methylates (mono & asymmetric dimethylation) the guanidino nitrogens of arginyl residues present in a glycine and arginine-rich domain (may methylate HNRNPA1 and histones). Methylates SUPT5H.
The PRMT1 protein functions as a histone methyltransferase specific for H4.
PRMT1 is an essential factor in oncogenesis and is a potential novel therapeutic target in cancer.
PRMT1-mediated methylation serves as a positive modulator of IR/IRS-1/PI3K pathway and glucose uptake in skeletal muscle cells.
CAF1 is a new regulator of PRMT1-dependent arginine methylation.
PRMT1 arginine-methylates MRE11 therefore it regulates the activity of MRE11-RAD50-NBS1 complex during the intra-S-phase DNA damage checkpoint response.
PRMT1 plays a post-translationally part in regulating the transcriptional activity.
PRMT1 is found predominantly in the cytoplasma though a fraction of PRMT1 is located in the nucleus.

SHC1 is a member of the SH2 domain family. SHC1 is vital to the regulation of apoptosis and drug resistance in mammalian cells. SHC1 is a signaling adapter which links activated growth factor receptors to signaling pathway. SHC1 is found in neural stem cells but not in mature neurons.

SNTA1 is a member of the syntrophin gene family. SNTA1 is a peripheral membrane protein found linked with dystrophin and dystrophin-related proteins. Dystrophin is a large, rod-like cytoskeletal protein located at the inner surface of muscle fibers. Dystrophin is absent in Duchenne Muscular Dystrophy patients, however it is present in reduced amounts in Becker Muscular Dystrophy patients. Syntrophins are cytoplasmic peripheral membrane scaffold proteins and components of the dystrophin-associated protein complex. The N-terminal PDZ domain of SNTA1 interacts with the C-terminus of the pore-forming alpha subunit (SCN5A) of the cardiac sodium channel Nav1.5. In addition, SNTA1 associates cardiac sodium channels with the nitric oxide synthase-PMCA4b (plasma membrane Ca-ATPase subtype 4b) complex in cardiomyocytes. The SNTA1 gene is a predisposition locus for Long-QT syndrome (LQT) - an inherited disorder associated with sudden cardiac death from arrhythmia - and sudden infant death syndrome (SIDS). SNTA1 also associates with dystrophin and dystrophin-related proteins at the neuromuscular junction and modifies intracellular calcium ion levels in muscle tissue.

Peptidoglycan Recognition Protein 1 (PGLYRP1) is a member of the N-acetylmuramoyl-L-alanine amidase 2 family. PGLYRP1 binds to peptidoglycan of bacteria and affects the peptidoglycan biosynthesis. PGLYRP1 displays bactericidal activity towards Gram-positive bacteria and is bacteriostatic towards Gram-negative bacteria. PGLYRP1 has a role in innate immunity. PGLYRP1 is highly expressed in the bone marrow, and weakly expressed in the kidney, liver, small intestine, spleen, thymus, peripheral leukocyte, lung, fetal spleen and neutrophils.

Apolipoprotein-D is mainly associated with high density lipoproteins in human plasma. Apolipoprotein-D is an atypical apolipoprotein and, based on its primary structure, Apolipoprotein-D is a member of the lipocalin family. Lipocalins adopt a beta-barrel tertiary structure and transport small hydrophobic ligands. Apolipoprotein-D binds cholesterol, progesterone, pregnenolone, bilirubin and arachidonic acid.
Apolipoprotein-D is expressed in numerous tissues having high levels of expression in spleen, testes and brain. Apolipoprotein-D is present at high concentrations in the cyst fluid of women with gross cystic disease of the breast, a condition associated with increased risk of breast cancer. Apolipoprotein-D accumulates in regenerating peripheral nerves and in the cerebrospinal fluid of patients with neurodegenerative conditions, such as Alzheimer's disease. Apolipoprotein-D participates in maintenance and repair within the central and peripheral nervous systems. Apolipoprotein-D is a multi-ligand, multi-functional transporter and transports a ligand from 1 cell to another within an organ, scavenge a ligand within an organ for transport to the blood or could transport a ligand from the circulation to specific cells within a tissue.

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.

RAB, Member RAS Oncogene Family-Like 5 (RABL5) belongs to the Ras superfamily of small GTP-binding proteins. The Ras-related superfamily of guanine nucleotide binding proteins includes the R-Ras, Rap, Ral/Rec and Rho/Rab subfamilies. Rab proteins have an essential role in endocytosis or in biosynthetic protein transport. The transporting process of newly synthesized proteins from the endoplasmic reticulum to various stacks of the Golgi complex and to secretory vesicles includes the movement of carrier vesicles and requires Rab protein function.

Ara h 1 is a seed storage protein from Arachis hypogaea which causes an allergic reaction in human. Ara h 1 is found in 95% of peanut allergic patients from North America. Nevertheless, peanut-allergic patients of European populations have fewer sensitizations to Ara h 1.

RTN4IP1 is a unique mitochondrial protein that interacts with reticulon 4, which is an effective inhibitor of regeneration ensuing spinal cord injury. The reticulon 4 interaction with mitochondrial proteins may offer insight into the mechanisms for reticulon-induced inhibition of neurite growth.

Mitochondrial antiviral signaling protein (MAVS) is vital for innate immune defense against viruses. MAVS is an intermediary protein essential in the virus-triggered IFN-beta signaling pathways. MAVS is involved in activation of transcription factors that regulate expression of IFN-beta and contributes to antiviral immunity.

MCL1 is a member of the Bcl-2 family. MCL1 takes part in the control of apoptosis against cell existence, and in the preservation of viability but not of proliferation. Alternative splicing happens at this locus and two transcript variants encoding different isoforms are known. Isoform 1 is the longer gene product and it increases cell existence by inhibiting apoptosis. Isoform 2 is a shorter gene product which indorses apoptosis and is death-inducing.

The 14-3-3 family of proteins plays a key regulatory role in signal transduction, checkpoint control, apoptotic and nutrient-sensing pathways. 14-3-3 proteins are highly conserved and ubiquitously expressed. There are at least seven isoforms that have been identified in mammals. The 14-3-3gamma, a subtype of the 14-3-3 family of proteins, was thought to be brain and neuron-specific. It has been shown to interact with RAF1 and protein kinase C, proteins involved in various signal transduction pathways.

STUB1, is a cytoplasmic protein whose amino acid sequence is highly preserved across species. STUB1 interacts with the molecular chaperones Hsc70-Hsp70 and Hsp90 through its TPR domain, whereas its U-box domain contains its E3 ubiquitin ligase activity. STUB1 interaction with these molecular chaperones lead to in client substrate ubiquitylation and degradation by the proteasome. therefore, STUB1 acts to tilt the folding-refolding mechanism towards the degradative pathway, and it serves as a link between the two. STUB1 inhibits anchorage-independent cell growth and metastatic potential by degrading oncogenic proteins including SRC-3. Inhibition of tyrosine kinase activity of Her-2/neu by quercetin specifies an lateration in the Her-2/neu structure which promotes STUB1 recruitments and down-regulation of Her-2/neu. STUB1 recognizes and mediates degradation of toxic, oligomeric forms of alphaSyn.

Diphthamide Biosynthesis 3 Pseudogene 1 also known as DPH3P1 may stand for a processed pseudogene of DPH3 since it lacks the exon/intron structurefound in the functional gene. Yet, DPH3P1 does contain an intact open reading frame, though its translation has not been established.