Search results

The protein kinase A holoenzyme is a heterotetramer composed of two types of subunits: Catalytic and Regulatory. The Catalyticsubunit contains the enzyme's active site. It also contains a domain that binds ATP and a domain that binds the regulatory subunit. The Regulatory subunit consists oftwo molecules which bind one another in an anti-parallel orientation to form a homodimer; for type I subunits- this binding is covalent via disulfide bonds. This subunit also has has two domains that bind cyclic AMP, a domain that interacts with a catalytic subunit, and an "auto-inhibitory" domain that serves as a substrate or pseudosubstrate for the catalytic subunit. Regulatory subunits may also have biologic activity distinct from their role in modulating catalytic subunit activity. Regulatory subunits exist in two major forms, RI and RII, with each form having two subtypes designated alpha and beta. Each of the four isotypes of the regulatory subunit is encoded by a different gene. In addition, three isotypes of the catalytic subunit have been identified (alpha, beta and gamma). The different isotypes tend to have different distributions within cells and among tissues. Type I enzymes inhabit cytoplasmic, soluble fractions of the cell, whereas type II enzymes tend to associate with cellular membranes.

The protein kinase A holoenzyme is a heterotetramer composed of two types of subunits: Catalytic and Regulatory. The Catalyticsubunit contains the enzyme's active site. It also contains a domain that binds ATP and a domain that binds the regulatory subunit. The Regulatory subunit consists oftwo molecules which bind one another in an anti-parallel orientation to form a homodimer; for type I subunits- this binding is covalent via disulfide bonds. This subunit also has has two domains that bind cyclic AMP, a domain that interacts with a catalytic subunit, and an "auto-inhibitory" domain that serves as a substrate or pseudosubstrate for the catalytic subunit. Regulatory subunits may also have biologic activity distinct from their role in modulating catalytic subunit activity. Regulatory subunits exist in two major forms, RI and RII, with each form having two subtypes designated alpha and beta. Each of the four isotypes of the regulatory subunit is encoded by a different gene. In addition, three isotypes of the catalytic subunit have been identified (alpha, beta and gamma). The different isotypes tend to have different distributions within cells and among tissues. Type I enzymes inhabit cytoplasmic, soluble fractions of the cell, whereas type II enzymes tend to associate with cellular membranes.

Casein kinase 2 subunit alpha (CSNK2A2) controls numerous cellular processes, such as cell cycle progression, apoptosis and transcription, as well as viral infection. CSNK2A2 protein functions as a regulatory node which integrates and coordinates numerous signals leading to an appropriate cellular response.

Thymidine kinase 2 mitochondrial (TK2) is a member of the DCK/DGK family. TK2 is an enzyme, a phosphotransferase (a kinase): 2'-deoxythymidine kinase, ATP-thymidine 5'-phosphotransferase. Thymidine kinase is found in most living cells. Thymidine kinase is present in 2 forms in mammalian cells, TK1 and TK2. Thymidine kinases have a central function in the synthesis of DNA and thus in cell division, since they are part of the exceptional reaction chain to introduce deoxythymidine into the DNA. TK2 is a deoxyribonucleoside kinase which specifically phosphorylates thymidine, deoxycytidine, and deoxyuridine. TK2 localizes to the mitochondria and is essential for mitochondrial DNA synthesis. TK2 gene defects are a cause of mitochondrial DNA depletion syndrome type 2 (MTDPS2).

Dual-Specificity Tyrosine-(Y)-Phosphorylation Regulated 1A (DYRK1A) belongs to the dual-specificity tyrosine phosphorylation-regulated kinase (DYRK) family. DYRK1A includes a nuclear targeting signal sequence, a leucine zipper motif and a protein kinase domain. DYRK1A catalyzes its autophosphorylation on serine/threonine and tyrosine residues and takes part in a signaling pathway regulating cell proliferation. DYRK1A has a substrate preference for proline at position P+1 and arginine at position P-3.

PDXK converts vitamin B6 to Pyridoxal-5-phosphate (PLP), which is a vital cofactor in the intermediate metabolism of amino acids and neurotransmitters. PDXK is cytoplasmic and probably acts as a homodimer. The biological validity of the alternatively spliced transcript variants has not been determined.

Casein Kinase 2 also called CK2 (also called PKCK2) is a ubiquitous Ser/Thr kinase expressed in all eukaryotes. CK2 is a tetramer composed of two catalytic kinase domains, alpha subunits, and two identical regulatory beta subunits. It has been implicated in cell cycle control, DNA repair, regulation of the circadian rhythm, and other cellular processes. The beta subunit itself does not have kinase activity, but confers stability to the CK2 alpha subunit and is involved in activity and substrate specificity.

Casein Kinase 2 beta (CSNK2B) is a ubiquitous Ser/Thr kinase expressed in all eukaryotes. CSNK2Bis atetramer comprised of 2 catalytic kinase domains, alpha subunits and 2 identical regulatory beta subunits.CSNK2Btakes part incell cycle control, DNA repair,regulation of the circadian rhythm and other cellularprocesses. The beta subunit itself confers stability to the CK2 alpha subunitand is involved in activity and substrate specificity but does not have kinase activity.

COAA is a member of the prokaryotic pantothenate kinase family and it is the first enzyme in the Coenzyme A biosynthetic pathway. COAA phosphorylates pantothenate (vitamin B5) to form 4'-phosphopantothenate. The key factor controlling the intracellular CoA concentration is the regulation of COAA activity by feedback inhibition.

Serine/threonine-protein kinase 16 (STK16) is a membrane-associated protein kinase which phosphorylates on serine and threonine residues. STK16 is involved in secretory vesicle trafficking or intracellular signaling. Furthermore, the STK16 protein may have a role in regulating stromal-epithelial interactions which occur during ductal morphogenesis in the mammary gland. STK16 can autophosphorylate on Tyr residue; it is however unclear whether STK16 has tyrosine-protein kinase toward other proteins. STK16 may also be involved in TGF-beta signaling.

Adenosine Kinase is an abundant enzyme in mammalian tissues which catalyzes the transfer of the gamma-phosphate from ATP to adenosine, thus is as a regulator of concentrations of both extracellular adenosine and intracellular adenine nucleotides. Adenosine has extensive effects on the cardiovascular, nervous, respiratory, and immune systems and inhibitors of the enzyme take a crucial pharmacological part in growing intravascular adenosine concentrations and acting as anti-inflammatory agents.

UMP-CMP kinase and deoxycytidylate kinase (CMPK1) is an enzyme which catalyzes the phosphoryl transfer from ATP to UMP, CMP and dCMP. This enzymatic reaction brings about the formation of ADP and the corresponding nucleoside diphosphate that are necessary for cellular nucleic acid synthesis. In addition, CMPK1 has a significant role in the activation of pyrimidine analogs, which are clinically useful anti-cancer and anti-viral drugs.

CDK16 is a member of the CDK family of serine/threonine protein kinases which are known to regulate the cell cycle. These proteins have a core kinase domain flanked by unique amino- and carboxy- terminal domains. CDK16, which is expressed mainly in mammalian brain, cooperates with an assortment of proteins, and is a part of a multiple signal transduction cascade.

UCK1 is a uridine-cytidine kinase which catalyzes the phosphorylation of uridine and cytidine to uridine monophosphate and cytidine monophosphate. UCK1 does not phosphorylate deoxyribonucleosides or purine ribonucleosides. UCK1 is also phosphorylates uridine and cytidine analogs and uses ATP and GTP as a phosphate donor.

Flavokinase is a transferases family member, specifically those transferring phosphorus-containing groups (phosphotransferases) with an alcohol group as acceptor. Flavokinase is an enzyme that catalyzes the phosphorylation of riboflavin (vitamin B2) to form flavin-mononucleotide (FMN), which is an obligatory step in vitamin B2 utilization and flavin cofactor synthesis. It has been proposed that TNF, through the activation of the RFK gene, enhances the incorporation of FAD in NADPH oxidase enzymes, which is a critical step for the assembly and activation of NADPH oxidase.

PFKM is a regulatory glycolytic enzyme that converts fructose 6-phosphate and ATP into fructose 1,6-bisphosphate (through PFK-1), fructose 2,6-bisphosphate (through PFK-2) and ADP. Three phosphofructokinase isozymes exist in humans: muscle, liver and platelet. Mutations in PFKM gene have been related with glycogen storage disease type VII, also identified as Tarui disease.

MAP2K1 is a member of the dual specificity protein kinase family, which plays a role as a mitogen-activated protein (MAP) kinase kinase. MAP kinases, are recognized as extracellular signal-regulated kinases (ERKs), that act as an integration position for multiple biochemical signals. MEK1 is located upstream of MAP kinases and stimulates the enzymatic activity of MAP kinases upon wide variety of extra- and intracellular signals. As a key player of MAP kinase signal transduction pathway, MEK1 is involved in many cellular processes such as proliferation, differentiation, transcription regulation and development. MAP2K1 catalyzes the concomitant phosphorylation of a threonine and a tyrosine residue in a thr-glu-tyr sequence located in map kinases. MEK1 activates erk1 and erk2 map kinases.

AKT Serine/Threonine Kinase 3 (Akt3) is a member of the Akt subfamily of serine/threonine protein kinases. Akt3is 1/3 closely related serine/threonine-protein kinases (Akt1, Akt2 and Akt3) called the Akt kinase and which regulate various processes including proliferation, metabolism, cell survival, growth and angiogenesis. The mentioned above is mediated through serine and/or threonine phosphorylation of a range of downstream substrates. Akt3 takes part in brain development and is critical for the viability of malignant glioma cells.

P85a functions as the regulatory subunit of the class IA PI3-kinase isoforms a, b, and d.
It contains two SH2 domains that bind to tyrosine-phosphorylated growth factor receptors or substrate adaptor proteins.
It also contains a BH (breakpoint cluster region homology) domain that shows GAP activity towards the small GTPases Rab4, Rab5, Cdc42, Rac1 and to a lesser extend towards Rab6 and Rab11.
It was shown that PI3Ka catalytic subunit mediated phosphorylation of the p85a adapter reduces the lipid kinase activity of the heterodimer and this gives hints for PI3K-dependent signaling events not requiring production of 3’-phosphorylated phosphoinositides.
PI3Ka protein kinase activity has been implicated in IRS-1 serine phosphorylation in insulin-treated adipocytes and in STAT3 and IRS-1 phosphorylation upon activation of the type 1 IFN receptor by IFN-a.

AK4 belongs to the adenylate kinase family of enzymes. AK4 protein is restricted to the mitochondrial matrix. Adenylate kinases regulate the adenine and guanine nucleotide structures in a cell by catalyzing the reversible transfer of phosphate group among these nucleotides. Hereditary mutations which cause AK4 deficiencies in erythrocytes have been associated to hemolytic anemia.

MAPK14 belongs to the MAP kinase family and is most associated with p38 MAP kinases(MAPKs). MAPKs are activated mainly as a reaction to cellular stress and inflammatory cytokines, and inhibitors that target the MAPK14 and MAPK11 have demonstrated ability to cure inflammatory disease. The substrates of this kinase contain transcription regulator ATF2, MEF2C, and MAX, cell cycle regulator CDC25B, and tumor suppressor p53, which demonstrate the parts of MAPK14 in stress-related transcription, cell cycle regulation and genotoxic stress response.

Cyclin-dependent kinase inhibitors (CDKIs) are proteins that bind to and inhibit the activity of CDKs. Two major classes of CDK inhibitors have been identified. The p16 family (p15, p16, p18 and p19) binds to and inhibits the activities of CDK4 and CDK6. The p21 family (p21, p27, p28 and p57) can bind to broad range of CDK-cyclin complexes and inhibit their activities. CDKIs are capable of suppressing growth, and several lines of evidence strongly suggest that at least some CDKIs may be tumor suppressor proteins.

SKP1 is a F-box enzyme which functions as a substrate recognition component of the SCF ubiquitin ligase complex which controls the ubiquitination of proteins involved in cell cycle progression, signal transduction and transcription. SKP1 binds to proteins containing an F-box motif, such as cyclin F, S-phase kinase-associated protein 2, and other regulatory proteins involved in ubiquitin dependent proteolysis. SKP1 takes part in the control of beta-catenin levels and the activity of beta-catenin dependent TCF transcription factors. SKP1 serves as an adapter that links the F-box protein to CUL1 in the SCF complex.

Serum-and glucocorticoid-regulated kinase (SGK1) is a serine/threonine protein kinase and a member of the “AGC” subfamily, which includes protein kinases A, G, and C. The SGK1 protein has an imperative role in activating specific potassium, sodium and chloride channels, suggesting a participation in the regulation of processes such as cell survival, neuronal excitability, and renal sodium excretion. SGK1 is activated in vitro by PDK-1 (3-phosphoinositide-dependent protein kinase-1) and in vivo in reaction to signals which activate phosphatidylinositol (PI) 3-kinase.