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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.

Creatine Kinase, Mitochondrial 2 (CKMT2) is a member of the ATP:guanido phosphotransferase family. CKMT2 is responsible for the transfer of high energy phosphate from mitochondria to the cytosolic carrier, creatine. CKMT2 reversibly catalyzes the transfer of phosphate between ATP and various phosphogens (e.g. creatine phosphate). Creatine kinase isoenzymes have a principal role in energy transduction in tissues with large, variable energy demands, such as skeletal muscle, heart, brain and spermatozoa. Mitochondrial creatine kinase occurs in 2 different oligomeric forms: dimers and octamers, contrary to the exclusively dimeric cytosolic creatine kinase isoenzymes. The CKMT2 gene contains sequences homologous to a number of motifs which are shared among some nuclear genes encoding mitochondrial proteins and therefore may be crucial for the coordinated activation of these genes during mitochondrial biogenesis.

p38a/SAPK2 is a member of the MAP kinase family. MAP kinases act as an integration point for multiple biochemical signals, and are involved in a wide variety of cellular processes such as proliferation, differentiation, transcription regulation and development. This kinase is activated by various environmental stresses and proinflammatory cytokines. The activation requires its phosphorylation by MAP kinase kinases (MKKs), or its autophosphorylation triggered by the interaction of MAP3K7IP1/TAB1 protein with this kinase. The substrates of this kinase include transcription regulator ATF2, MEF2C, and MAX, cell cycle regulator CDC25B, and tumor suppressor p53, which suggest the roles of this kinase in stress related transcription and cell cycle regulation, as well as in genotoxic stress response. Four alternatively spliced transcript variants of this gene encoding distinct isoforms have been reported.

Inositol-tetrakisphosphate 1-kinase (ITPK1) is a 414 amino acid monomer which is a member of the ITPK1 family and exists as 2 alternatively spliced isoforms. ITPK1 highest levels are found in the brain, followed by the heart, skeletal muscle, kidney, pancreas, liver, placenta and lung. ITPK1 is comprised of one ATP-grasp domain and has been shown to phosphorylate various inositol polyphosphates and modify TNFa induced apoptosis.

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.

E.Coli Acetate Kinase, also knowns as ACKA, catalyzes the formation of acetyl phosphate from acetate and ATP and also catalyzes the reverse reaction. ACKA takes part in synthesis of various ATP formed catabolically during anaerobic growth of the organism.

The Casein kinase 2 (EC2.7.11.1) is a serine/threonine-selective protein kinasethat is a tetramer of two alpha subunits and two beta subunits. The alpha subunits have the catalytic kinase domain. Casein kinase 2 has been implicated in cell cyclecontrol, DNA repair, regulation of the circadian rhythmand other cellular processes.
Casein kinase 2 activity has been reported to be activated following Wnt signaling pathwayactivation. A Pertussis toxin-sensitive G proteinand Disheveled appear to be an intermediary between Wnt-mediated activation of the Frizzled receptor and activation of casein kinase 2.

Akt1, also known as "Akt" or protein kinaseB (PKB) is an important molecule in mammaliancellular signaling.
In humans, there are three genes in the "Akt family": Akt1, Akt2, and Akt3. These enzymesare members of the serine/threonine-specific protein kinasefamily (EC2.7.11.1).
Akt1 is involved in cellular survival pathways, by inhibiting apoptoticprocesses. Akt1 is also able to induce protein synthesispathways, and is therefore a key signaling protein in the cellular pathways that lead to skeletal muscle hypertrophy, and general tissue growth. Since it can block apoptosis, and thereby promote cell survival, Akt1 has been implicated as a major factor in many types of cancer. Akt (now also called Akt1) was originally identified as the oncogenein the transforming retrovirus, AKT8.

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.

Caseine Kinase 1 alpha belongs is a member of the protein kinase superfamily, CK1 Ser/Thr protein kinase family, Casein kinase I subfamily. The CK1 isoforms - alpha, beta, gamma, delta, epsilon and their splice variants are involved in diverse cellular processes including membrane trafficking, circadian rhythm, cell cycle progression, chromosome segregation, apoptosis and cellular differentiation. Possibly CSNK1A1 can phosphorylate a large number of proteins and is involved in Wnt signaling where it phosphorylates CTNNB1 on Ser45. CSNK1A1 also interacts with the Axin complex.

Extracellular signal-regulated kinases (ERKs) or classical MAP kinases are widely expressed protein kinaseintracellular signalingmolecules which are involved in functions including the regulation of meiosis, mitosis, and postmitotic functions in differentiated cells. Many different stimuli, including growth factors, cytokines, virusinfection, ligands for heterotrimeric G protein-coupled receptors, transforming agents, and carcinogens, activate the ERK pathway.
The term, "extracellular signal-regulated kinases", is sometimes used as a synonym for mitogen-activated protein kinase(MAPK), but has more recently been adopted for a specific subset of the mammalianMAPK family. In the MAPK/ERK pathway, Rasactivates c-Raf, followed by MEKand then MAPK1/2 (below). Ras is typically activated by growth hormones through receptor tyrosine kinasesand GRB2/SOS, but may also receive other signals. ERKs are known to activate many transcription factors and some downstream protein kinases. Disruption of the ERK pathway is common in cancers, especially Ras, c-Raf and receptors such as HER2.Mitogen-activated protein kinase 3 (MAPK3) is also known as "extracellular signal-regulated kinase 1" (ERK1). Transgenic gene knockoutmice lacking MAPK3 are viable and it is thought that MAPK1 can fulfill most MAPK3 functions in most cells. The main exception is in T cells. Mice lacking MAPK3 have reduced T cell development past the CD4+CD8+ stage.

Mitogen-activated protein kinase 1 (MAPK1) is also known as "extracellular signal-regulated kinase 2" (ERK2). Two similar (85% sequence identity) protein kinases were originally called ERK1 and ERK2. They were found during a search for protein kinases that are rapidly phosphorylated after activation of cell surface tyrosine kinasessuch as the epidermal growth factor receptor. Phosphorylation of ERKs leads to the activation of their kinase activity. The molecular events linking cell surface receptors to activation of ERKs are complex. It was found that RasGTP-binding proteins are involved in the activation of ERKs. Another protein kinase, Raf-1, was shown to phosphorylate a "MAPK kinase", thus qualifying as a "MAPK kinase kinase". The MAPK kinase was named "MAPK/ERK kinase" (MEK). Receptor-linked tyrosine kinases, Ras, Raf, MEK and MAPK could be fitted into a signaling cascade linking an extracellular signal to MAPK activation. Transgenic gene knockoutmice lacking MAPK1 have major defects in early development.

The Casein kinase 2 (EC2.7.11.1) is a serine/threonine-selective protein kinasethat is a tetramer of two alpha subunits and two beta subunits. The alpha subunits have the catalytic kinase domain. Casein kinase 2 has been implicated in cell cyclecontrol, DNA repair, regulation of the circadian rhythmand other cellular processes.
Casein kinase 2 activity has been reported to be activated following Wnt signaling pathwayactivation. A Pertussis toxin-sensitive G proteinand Disheveled appear to be an intermediary between Wnt-mediated activation of the Frizzled receptor and activation of casein kinase 2.
Mice that lack casein kinase 2 alpha prime have a defect in the morphology of developing sperm.

PDK1 takes part in the regulation of enzymatic activity of mammalian pyruvate dehydrogenase which is part of a mitochondrial multienzyme complex to catalyze the oxidative decarboxylation of pyruvate and is one of the major enzymes responsible for the regulation of homeostasis of carbohydrate fuels in mammals. PDK1 inhibits glioblastoma growth. PDK1 inhibits the mitochondrial pyruvate dehydrogenase complex by phosphorylation of the e1 alpha subunit, therefore contributing to the regulation of glucose metabolism. PDK1 kinase activity is negatively regulated by binding to 14-3-3.

C-Src Tyrosine Kinase, also known as CSK, regulates cell growth, migration, differentiation, and immune response. CSK Phosphorylates tyrosine residues located in the C-terminal tails of Src-family kinases. CSK is a protein coding gene which suppresses signaling by several surface receptors. Among CSK's related pathways are PI-3K cascade and Signaling by FGFR.

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.

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.

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).

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.

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.

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.

GALK1 enzyme is needed in the first step of the galactose metabolism pathway.
(ATP + D-galactose = ADP + alpha-D-galactose 1-phosphate). GALK1 deficinecy lead galactosemia II which is an autosomal recessive deficiency known by congenital cataracts during infancy and presenile cataracts in the adult population. The cataracts are secondary to accumulation of galactitol in the lenses.

PINK1 is a serine/threonine protein kinase which is found in the mitochondria. PINK1 shields cells from stress-induced mitochondrial dysfunction. Mutations results in one form of autosomal recessive early-onset Parkinson disease.