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The Regulatory (R) subunit of Protein Kinase A (PKA) inhibits its kinase activity by shielding the Catalytic (C) subunit from physiological substrates. This inhibition is reversed in response to extra-cellular signals that increase cAMP levels in the cytoplasm. Upon cAMP binding to R, C is allosterically released from R, activating a spectrum of downstream signaling cascades. Crystallographic data indicated that a series of distinct conformational changes within CBD-A must occur to relay the cAMP signal from the cAMP binding site to the R:C interaction interface. One critical cAMP relay site within the CBD-A of R has been identified as Asp170 because the D170A mutation selectively reduces the negative cooperativity between the cAMP- and C-recognition sites (i.e. the KD for the R:C complex in the presence of cAMP is reduced by more than 12-fold), without significantly compromising the high affinity of R for both binding partners.

Mitogen-Activated Protein Kinase 6 (MAP2K6) is a part of the dual specificity protein kinase family. MAP2K6 phosphorylates and activates p38 MAP kinase in response to inflammatory cytokines or environmental stress. MAP2K6 is a vital component of the MAP kinase signal transduction pathway. MAP2K6 takes part in various cellular processes such as stress induced cell cycle arrest and apoptosis.

AKR7A2 participates in the detoxification of aldehydes and ketones. AKR7A2 catalyzes the NADPH-dependent reduction of succinic semialdehyde to gamma-hydroxybutyrate. AKR7A2 is involved in producing the neuromodulator gamma-hydroxybutyrate (GHB). AKR7A2 has extensive substrate specificity. AKR7A2 shows NADPH-dependent aldehyde reductase activity towards 2-carboxybenzaldehyde, 2-nitrobenzaldehyde and pyridine-2-aldehyde (in vitro). AKR7A2 reduces 1,2-naphthoquinone and 9,10-phenanthrenequinone (in vitro). AKR7A2 reduces the dialdehyde protein-binding form of aflatoxin B1 (AFB1) to the non-binding AFB1 dialcohol. AKR7A2 takes part in protection of liver against the toxic and carcinogenic effects of AFB1, a potent hepatocarcinogen.

Cyclin-dependent kinase inhibitor 1B (CDKN1B) is a member of the Cip/Kip family of cyclin dependent kinase (Cdk) inhibitor proteins. The CDKN1B protein binds to and prevents the activation of cyclin E-CDK2 or cyclin D-CDK4 complexes, and so controls the cell cycle progression at G1. CDKN1B is often referred to as a cell cycle inhibitor protein since its major function is to stop or slow down the cell division cycle. The degradation of the CDKN1B protein, which is triggered by its CDK dependent phosphorylation and ensuing ubiquitination by SCF complexes, is compulsory for the cellular transition from inactive to the proliferative state.

Pyruvate kinase is a key enzyme in the glycolytic pathway. The M2 isoenzyme of pyruvate kinase is specifically expressed at high levels in tumor cells, and can be measured in plasma of patients with advanced breast cancer. The marker is useful for measuring disease activity, sensitivity to chemotherapy and recurrence.

CDKN1A holds a key part in the cellular response to DNA mutation. CDKN1A overexpression causes cell cycle to stop. When collaborating with CDK2 complexes, CDKN1A aids to prevent kinase activity and inhibits progression through G1/S. Nevertheless, CDKN1A can additionally increase assembly and activity in complexes of CDK4 or CDK6 and cyclin D. CDKN1A is a vital intermediary by which p53/TP53 facilitates its part as an inhibitor of cellular proliferation as a reaction to DNA impairment.

Phosphomevalonate kinase (PMVK) is a cytosolic enzyme. PMVK is expressed highly in the heart, liver, skeletal muscle, kidney and pancreas and slightly lower in the brain, placenta, and lung. PMVK catalyzes the conversion of mevalonate 5-phosphate into mevalonate 5-diphosphate in the fifth reaction of the cholesterol biosynthetic pathway. Induced by sterol, PMVK participates in isopentenyl diphosphate biosynthesis via the mevalonate pathway.

AHCY is an enzyme that catalyzes the reversible hydrolysis of S-adenosylhomocysteine (AdoHcy) to adenosine (Ado) and L-homocysteine (Hcy). AHCY controls the intracellular S-adenosylhomocysteine (SAH) concentration that is crucial for transmethylation reactions. AHCY deficiency causes hypermethioninemia.

PI3Ka plays a specific role in apoptosis in human colon cancer cells. Injection of neutralizing antibodies specific to PI3Ka into adenocarcinoma cells induced apoptosis, a response that was reverted by treating cells with caspase inhibitor. It was also shown that PI3Ka 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 is a key regulator of the initiation of keratinocyte differentiation. A decrease in PI3Ka activity results in a loss of keratinocyte adhesion to the extracellular membrane and the initiation of early phase differentiation.

Adenylosuccinate lyase (ADSL) is an enzyme which converts adenylosuccinate to AMP and fumarate as part of the purine nucleotide cycle. ADSL is involved in both de novo synthesis of purines and formation of adenosine monophosphate from inosine monophosphate. ADSL catalyzes 2 reactions in AMP biosynthesis: the removal of a fumarate from succinylaminoimidazole carboxamide (SAICA) ribotide to yield aminoimidazole carboxamide ribotide (AICA) and removal of fumarate from adenylosuccinate to yield AMP. Defects in the ADSL are the cause of adenylosuccinase deficiency (ADSL deficiency). ADSL deficiency is an autosomal recessive disorder distinguished by the accumulation in the body fluids of succinylaminoimidazole-carboxamide riboside (SAICA-riboside) and succinyladenosine (S-Ado). Adenylosuccinase deficiency results in succinylpurinemic autism, psychomotor retardation, and in some cases, growth retardation associated with muscle wasting and epilepsy.

Cyclin-dependent kinase 2 (CDK2) belongs the Ser/Thr protein kinase family. CDK2 is highly parallel to the gene products of S. cerevisiae cdc28, and S. pombe cdc2. CDK2 is a catalytic subunit of the cyclin-dependent protein kinase complex, whose activity is limited to the G1-S phase, and is vital for cell cycle G1/S phase transition. The CDK2 protein associates with and is regulated by the regulatory subunits of the complex including cyclin A or E, CDK inhibitor p21Cip1 (CDKN1A) and p27Kip1 (CDKN1B). CDK2 activity is also regulated by protein phosphorylation.

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.

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.

MAPK12 is a member of the MAP kinase family. MAPK12 acts as a signal transducer during differentiation of myoblasts to myotubes. p38 proteins utilizes magnesium as a cofactor to catalyze the ATP-dependent phosphorylation of target proteins and is produced in several regions all over the body with common expression patterns in heart.

PGK2 is a testis-specific form of phosphoglycerate kinase. Originally presumed to be a pseudogene, the PGK2 protein is actually a functional phosphoglycerate kinase which catalyzes the reversible conversion of 1,3-bisphosphoglycerate to 3-phosphoglycerate, during the Embden-Meyerhof-Parnas pathway of glycolysis, in the later stages of spermatogenesis. The PGK2 gene is intronless, results from retrotransposition of the phosphoglycerate kinase 1 gene, and is expressed specifically in the testis.

ILK1 (Integrin-linked kinase) is a serine/threonine protein kinase, containing 4 ankyrin-like repeats. ILK1 regulates a number of biological properties which include: anchorage-independent cell cycle progression, tumor cell invasion and apoptosis. ILK1 can also be implicated in mediating cell architecture, adhesion to integrin substrates and anchorage-dependent growth in epithelial cells. Furthermore, ILK1 phosphorylates beta-1 and beta-3 integrin subunit on serine and threonine residues, but also AKT1 and GSK3B.
ILK1 interacts with the cytoplasmic domains of integrin ?1 and ?3 subunits in addition to several adaptors and signaling proteins, it also acts as a proximal receptor kinase regulating integrin-mediated signal transduction. ILK1 is a focal adhesion protein part of the complex ILK-PINCH. This complex is deemed to be one of the convergence points of integrin- and growth factor-signaling pathway. ILK1 is stimulated rapidly but briefly by both cell fibronectin interactions in a PI3-K-dependent manner, probably through the binding of PtdIns(3,4,5)P3 with a PH-like domain of ILK.
ILK1 over-expression has been documented in a wide variety of human malignancies.

Acyl CoA dehydrogenase is the enzymeused to catalyzethe first step of ?-oxidationin Fatty acid metabolism.
Acyl-coenzyme A (CoA) dehydrogenases (ACADs) are a family of mitochondrial enzymes that catalyze the first dehydrogenation step in the bets-oxidation of fatty acyl-CoA derivatives. Several human ACADs exist and all ACADs catalyze the same initial dehydrogenation of the substrate at the beta-carbon atom and require electron transfer flavoprotein as an alectron acceptor. The predicted 415-amino acid ACAD8 protein contains many of the residues conserved in most other ACADs, including an active site glutamic acid residue and residues important for tetramer formation.

APRT is part of the purine/pyrimidine phosphoribosyltransferase family. APRT enzyme catalyzes the formation of AMP and inorganic pyrophosphate from adenine and 5-phosphoribosyl-1-pyrophosphate (PRPP). APRT produces adenine as a by-product of the polyamine biosynthesis pathway. A homozygous deficiency in APRT causes 2,8-dihydroxyadenine urolithiasis. APRT catalyzes a salvage reaction resulting in the formation of AMP.

Acireductone dioxygenase 1 (ADI1) is a part of the acireductone dioxygenase family of metal-binding enzymes, which are involved in methionine salvage. ADI1 regulates mRNA processing in the nucleus, and carries out different functions depending on its localization. Related pseudogenes have been defined on chromosomes 8 and 20. ADI1 down-regulates cell migration arbitrated by MMP14.

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.

Calcium/Calmodulin Dependent Protein Kinase II Inhibitor 1 (CAMK2N1), which interacts with CAMK2B, is a part of the CAMK2N family. CAMK2N1 is also interacts with CAMK2A in a way which requires CAMK2A activation by Ca2+. CAMK2N1 is potent and specific inhibitor of CaM-kinase II (CAMK2).

Aldo-keto reductase family 1 member D1 (AKR1D1) belongs to the AKR superfamily. The AKR family proteins are soluble NADPH oxidoreductases, which have vital roles in the metabolism of drugs, carcinogens and reactive aldehydes. AKR1D1 is also responsible for the catalysis of the 5-beta-reduction of bile acid intermediates and steroid hormones that carry a delta (4)-3-1 structure. AKR1D1 is highly expressed in the liver, colon and testis. Deficiency of the AKR1D1 enzyme may contribute to hepatic dysfunction.

Aldo-keto reductase family 1 member D1 (AKR1D1) belongs to the AKR superfamily. The AKR family proteins are soluble NADPH oxidoreductases, which have vital roles in the metabolism of drugs, carcinogens and reactive aldehydes. AKR1D1 is also responsible for the catalysis of the 5-beta-reduction of bile acid intermediates and steroid hormones that carry a delta (4)-3-1 structure. AKR1D1 is highly expressed in the liver, colon and testis. Deficiency of the AKR1D1 enzyme may contribute to hepatic dysfunction.

Mitogen-Activated Protein Kinase Kinase 2 (MAP2K2) is a dual specificity protein kinase, which is a member of the STE grouping of kinases and the MAP kinase kinase family. MAP2K2 is activated by a wide range of growth factors and cytokines and also by membrane depolarization and calcium influx. The MAP2K2 kinase is known for its vital role in mitogen growth factor signal transduction. MAP2K2 phosphorylates and consequently activates MAPK1/ERK2 and MAPK2/ERK3. The activation of the MAP2K2 kinase itself is dependent on the Ser/Thr phosphorylation by MAP kinase kinase kinases. The inhibition or degradation of the MAP2K2 kinase is also found to be involved in the pathogenesis of Yersinia and anthrax. MAP2K2 gene mutations cause cardiofaciocutaneous syndrome (CFC syndrome).