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Proteasome subunit alpha type 4 (PSMA4) belongs to the peptidase T1A family, which is a 20S core alpha subunit. The proteasome is a multicatalytic proteinase complex with an extremely ordered ring-shaped 20S core structure. The core structure is comprised of 4 rings of 28 non-identical subunits; 2 rings are composed of 7 alpha subunits and 2 rings are composed of 7 beta subunits. PSMA4 is dispersed throughout eukaryotic cells at a high concentration and cleaves peptides in an ATP/ubiquitin-dependent process in a non-lysosomal pathway.

Polyribonucleotide nucleotidyltransferase 1, also known as PNPT1 is predominantly localized in the mitochondrial intermembrane space and is implicated in the import of RNA to mitochondria. Mutations in PNPT1 have been connected with combined oxidative phosphorylation deficiency-13 as well as autosomal recessive nonsyndromic deafness-70. Related pseudogenes have been found on chromosomes 3 & 7.

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 hyperinsulinemia and insulin resistance 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.

YOD1 is a Hydrolase which removes conjugated ubiquitin from proteins and takes part in endoplasmic reticulum-associated degradation (ERAD) for misfolded lumenal proteins. YOD1 is a highly conserved deubiquitinating enzyme belonging to the ovarian tumor (otubain) family, whose function has yet to be determined in mammalian cells. YOD1 is a component of a multiprotein complex with p97 as its nucleus, proposing a functional link to a pathway responsible for the dislocation of misfolded proteins from the endoplasmic reticulum. YOD1 variant xpression deprived of its deubiquitinating activity compels a halt on the dislocation reaction, as concluded by the stabilization of various dislocation substrates.

RAB39B, Member RAS Oncogene Family (RAB39B) belongs to the Rab family of proteins. Rab proteins are small GTPases, which are involved in vesicular trafficking. RAB39B gene mutations are linked with X-linked mental retardation.

Peptidyl-prolyl cis-trans isomerase NIMA-interacting 4 (PIN4) is a peptidyl-prolyl cis/trans isomerase (PPIase) which interacts with NIMA and is vital for cell cycle regulation. PIN4 has 2 different isoforms: PAR14 and PAR17. Furthermore, Pin4 protein binds to double-stranded DNA under physiological salt conditions.

Non-metastatic cells 1 or NME1 is a protein, found at first as a suppressor gene for candidate metastasis. The protein can be found in various types of tumor, potential of metastatic may increase or decrease as the protein’s levels changes. When the protein’s concentration is low, an aggressive carcinoma (colon, breast, gastric and melanoma) appears. High levels of NME1 have been linked to advanced thyroid cancer.

CTK-19 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. Unlike its related family members, this smallest known acidic cytokeratin is not paired with a basic cytokeratin in epithelial cells. It is specifically expressed in the periderm, the transiently superficial layer that envelopes the developing epidermis. The type I cytokeratins are clustered in a region of chromosome 17q12-q21.

Thrombin enzyme (Activated Factor IIa) is an important clotting promoter that controls the transformation of soluble fibrinogen to insoluble active fibrin strands. Thrombin is a coagulation protein and a serine protease (EC 3.4.21.5) that catalyzes many coagulation-related reactions. Thrombin triggers factor-XI, factor-V, Factor-XIII and factor-VIII. Thrombin endorses platelet activation, using activation of protease-activated receptors on the platelet. As a result of its high proteolytic specificity, thrombin has become an important biochemical protein. The thrombin cleavage site (Leu-Val-Pro-Arg-Gly-Ser) is widely used in linker regions of recombinant fusion protein constructs. After the purification of the fusion protein, thrombin is used to cleave between the Arginine and Glycine residues of the cleavage site, efficiently removing the purification tag from the protein of interest with a high degree of specificity.

SPINT2 is a transmembrane protein acts as an inhibitor of HGF activator. SPINT2 inhibits plasmin, plasma and tissue kallikrein, and factor XIa. SPINT2 has two extracellular Kunitz domains that inhibit few serine proteases. SPINT2 is assumed tumor suppressor, mutations in SPINT2 leads to a congenital sodium diarrhea.

TPM1 is a member of the tropomyosin family which consists of a number of extremely conserved, extensively distributed 35-45 kDa actin-binding proteins that are involved in the contractile system of striated and smooth muscles and the cytoskeleton of non-muscle cells. Tropomyosin-1 is composed of 2 alpha-helical chains arranged as a coiled-coil. TPM1 is polymerized end to end alongside the two grooves of actin filaments and provides stability to the filaments. TPM1 binds to actin filaments in muscle and non-muscle cells. TPM1 also functions in association with the troponin complex to regulate the calcium-dependent interaction of actin and myosin during muscle contraction. In non-muscle cells TPM1 is implicated in stabilizing cytoskeleton actin filaments. Smooth muscle contraction is controlled by interaction with caldesmon.
Alternatively spliced transcript variants encoding a range of isoforms have been described in smooth muscle and non-muscle cells. TPM1 Isoform 1 is expressed in adult and fetal skeletal muscle and cardiac tissues, with higher expression levels in the cardiac tissues, whereas Isoform 10 is expressed in adult and fetal cardiac tissues, but not in skeletal muscle.
Mutations in the TPM1 gene are linked to type 3 familial hypertrophic cardiomyopathy.

HSPA13 belongs to the heat shock protein 70 family and is related to microsomes. Members of this protein family take part in the processing of cytosolic and secretory proteins, in addition to the exclusion of denatured or incorrectly-folded proteins. HSPA13 is known to cooperate with PLIC-1 and PLIC-2, proteins which have a role in the signaling connection between the membrane receptors for thrombospondin and the cytoskeleton.

GAP43 is a phosphoprotein of the presynaptic membrane that takes part in synaptic reorganization and neural development. GAP43 is found in large quantities in neuronal growth cones all through the development and axonal regeneration. Additionally, GAP43 is involved in specific regions of the normal adult nervous system and has a vital part in the conservation mechanism of long-term potentiation (LTP).

Midkine (MK) is the product of a retinoic acid responsive gene, MK, and is a member of a family of heparin binding factors. It contains 121 amino acid residues including 10 conserved cysteine residues, all of which appear to be disulphide linked.
Midkine is expressed during embryogenesis, showing an expression pattern that suggests functions in neurogenesis, cell migration, secondary organogenetic induction, and mesoderm-epithelial interaction.
The widespread downregulation of MK in the adult human is reverted in a number of cancers, in which polypeptides are able to act as both transforming growth factors and promoters of angiogenesis.
Midkine (MK), induces chemotaxis of human neutrophils and was found to trigger mobilization of intracellular calcium of these cells.
Midkine induces histamine release from rat peritoneal mast cells with a rapid response in a dose dependent manner.
Midkine is also a potent stimulator of collagen and glycosaminoglycan synthesis.

KPNB1 is a member of the importin beta family. The KPNB1 protein is engaged in nuclear protein import, either by coupling itself with an adapter protein (e.g., importin-alpha subunit which binds to nuclear localization signals (NLS) in cargo substrates), or by functioning autonomously as a nuclear transport receptor (acts as NLS receptor, docking of the importin/substrate complex to the nuclear pore complex).

Ubiquitin-like domain-containing CTD phosphatase 1 (UBLCP1) dephosphorylates 26S nuclear proteasomes, thereby decreasing their proteolytic activity. The dephosphorylation averts assembly of the core and regulatory particles (CP and RP) into mature 26S proteasome.

RAB27A is part of the small GTPase superfamily, Rab family. RAB27A is membrane-bound and participates in protein transport and small GTPase mediated signal transduction. Mutations in this RAB27A are associated with Griscelli syndrome type 2. RAB27A is involved in cytotoxic granule exocytosis in lymphocytes.RAB27A is necessary for both granule maturation and granule docking and priming at the immunologic synapse.

Peroxisome proliferators are non-genotoxic carcinogens which are purported to exert their effect on cells through their interaction with members of the nuclear hormone receptor family termed peroxisome proliferators activated receptors (PPARs). Nuclear hormone receptors are ligand-dependent intracellular proteins that stimulate transcription of specific genes by binding to specific DNA sequences following activation by the appropriate ligand. Studies indicate that PPARs are activated by peroxisome proliferators such as clofibric acid, nafenopin, and WY-14,643, as well as by some fatty acids.

Clusterin also named Apolipoprotein J (APO-J) is a 75-80 kD disulfide-linked heterodimeric protein containing about 30% of N-linked carbohydrate rich in sialic acid but truncated forms targeted to the nucleus have also been identified.
The precursor polypeptide chain is cleaved proteolytically to remove the 22-mer secretory signal peptide and subsequently between residues 227/228 to generate the a and b chains. These are assembled in anti-parallel to give a heterodimeric molecule in which the cysteine-rich centers are linked by five disulfide bridges and are flanked by two predicted coiled-coil a-helices and three predicted amphipathic a-helices.
Across a broad range of species clusterin shows a high degree of sequence homology ranging from 70% to 80%. It is nearly ubiquitously expressed in most mammalian tissues and can be found in plasma, milk, urine, cerebrospinal fluid and semen.
It is able to bind and form complexes with numerous partners such as immunoglobulins, lipids, heparin, bacteria, complement components, paraoxonase, beta amyloid, leptin and others. Clusterin has been ascribed a plethora of functions such as phagocyte recruitment, aggregation induction, complement attack prevention, apoptosis inhibition, membrane remodeling, lipid transport, hormone transport and/or scavenging, matrix metalloproteinase inhibition.
A genuine function of clusterin has not been defined. One tempting hypothesis says that clusterin is an extracellular chaperone protecting cells from stress induced insults caused by degraded and misfolded protein precipitates.
Clusterin is up- or down regulated on the mRNA or protein level in many pathological and clinically relevant situations including cancer, organ regeneration, infection, Alzheimer disease, retinitis pigmentosa, myocardial infarction, renal tubular damage, autoimmunity and others.

EIF1AX is an important eukaryotic translation initiation factor. EIF1AX is essential for the binding of the 43S complex (a 40S subunit, eIF2/GTP/Met-tRNAi and eIF3) to the 5'' end of capped RNA. EIF1AP1 is needed for maximal rate of protein biosynthesis. EIF1AX increases ribosome dissociation into subunits and stabilizes the binding of the initiator Met-tRNA (I) to 40 S ribosomal subunits.

Proline-Rich Nuclear Receptor Coactivator 2 (PNRC2) takes part in controlling the energy balance between energy storage and energy expenditure. PNRC2 is involved in nonsense-mediated mRNA decay (NMD) by operating as a bridge between the mRNA decapping complex and the NMD machinery. PNRC2 is needed for UPF1/RENT1 localization to the P-body and also plays a role as a nuclear receptor coactivator.

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).

Cytokeratin 17 also known as KRT17 is a type I cytokeratin. KRT17 is found in nail beds, hair follicles, sebaceous glands, and other epidermal appendages. Mutations in KRT17 lead to Jackson-Lawler type pachyonychia congenita and steatocystoma multiplex. KRT17 takes part in the formation and maintenance of a variety of skin appendages, particularly in determining shape and orientation of hair. KRT17 also modulates the function of TNF-alpha in the precise context of hair cycling. Moreover, KRT17 regulates protein synthesis and epithelial cell growth all through binding to the adapter protein SFN and by stimulating Akt/mTOR pathway.