Kinome

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In molecular biology, biochemistry and cell signaling the kinome of an organism is the complete set of protein kinases encoded in its genome. Kinases are usually enzymes that catalyze phosphorylation reactions (of amino acids) and fall into several groups and families, e.g., those that phosphorylate the amino acids serine and threonine, those that phosphorylate tyrosine and some that can phosphorylate both, such as the MAP2K and GSK families. The term was first used in 2002 by Gerard Manning and colleagues in twin papers analyzing the 518 human protein kinases, and refers to both protein kinases and protein pseudokinases [1] and their evolution of protein kinases throughout the eukaryotes. [2] Other kinomes have been determined for rice, [3] several fungi, nematodes, and insects, sea urchins, [4] Dictyostelium discoideum , [5] and the process of infection by Mycobacterium tuberculosis . [6] Although the primary sequence of protein kinases shows substantial divergence between unrelated eukaryotes, and amino acid differences in catalytic motifs have permitted their separation of kinomes into canonical and pseudokinase subtypes, [7] the variation found in the amino acid motifs adjacent to the site of actual phosphorylation of substrates by eukaryotic kinases is much smaller. [8]

Contents

As kinases are a major drug target and a major control point in cell behavior, the kinome has also been the target of large scale functional genomics with RNAi screens and of drug discovery efforts, especially in cancer therapeutics. [9]

In animals, the kinome includes kinases that phosphorylate only tyrosine (tyrosine kinases), those that act on serine or threonine, and a few classes, such as GSK3 and MAP2K that can act on both.[ citation needed ] Research has shown that there are specialized protein domains that bind to phosphorylated serine and threonine residues, such as BRCA and FHA domains.[ citation needed ]

See also

Related Research Articles

<span class="mw-page-title-main">Protein kinase</span> Enzyme that adds phosphate groups to other proteins

A protein kinase is a kinase which selectively modifies other proteins by covalently adding phosphates to them (phosphorylation) as opposed to kinases which modify lipids, carbohydrates, or other molecules. Phosphorylation usually results in a functional change of the target protein (substrate) by changing enzyme activity, cellular location, or association with other proteins. The human genome contains about 500 protein kinase genes and they constitute about 2% of all human genes. There are two main types of protein kinase. The great majority are serine/threonine kinases, which phosphorylate the hydroxyl groups of serines and threonines in their targets. Most of the others are tyrosine kinases, although additional types exist. Protein kinases are also found in bacteria and plants. Up to 30% of all human proteins may be modified by kinase activity, and kinases are known to regulate the majority of cellular pathways, especially those involved in signal transduction.

A protein phosphatase is a phosphatase enzyme that removes a phosphate group from the phosphorylated amino acid residue of its substrate protein. Protein phosphorylation is one of the most common forms of reversible protein posttranslational modification (PTM), with up to 30% of all proteins being phosphorylated at any given time. Protein kinases (PKs) are the effectors of phosphorylation and catalyse the transfer of a γ-phosphate from ATP to specific amino acids on proteins. Several hundred PKs exist in mammals and are classified into distinct super-families. Proteins are phosphorylated predominantly on Ser, Thr and Tyr residues, which account for 79.3, 16.9 and 3.8% respectively of the phosphoproteome, at least in mammals. In contrast, protein phosphatases (PPs) are the primary effectors of dephosphorylation and can be grouped into three main classes based on sequence, structure and catalytic function. The largest class of PPs is the phosphoprotein phosphatase (PPP) family comprising PP1, PP2A, PP2B, PP4, PP5, PP6 and PP7, and the protein phosphatase Mg2+- or Mn2+-dependent (PPM) family, composed primarily of PP2C. The protein Tyr phosphatase (PTP) super-family forms the second group, and the aspartate-based protein phosphatases the third. The protein pseudophosphatases form part of the larger phosphatase family, and in most cases are thought to be catalytically inert, instead functioning as phosphate-binding proteins, integrators of signalling or subcellular traps. Examples of membrane-spanning protein phosphatases containing both active (phosphatase) and inactive (pseudophosphatase) domains linked in tandem are known, conceptually similar to the kinase and pseudokinase domain polypeptide structure of the JAK pseudokinases. A complete comparative analysis of human phosphatases and pseudophosphatases has been completed by Manning and colleagues, forming a companion piece to the ground-breaking analysis of the human kinome, which encodes the complete set of ~536 human protein kinases.

<span class="mw-page-title-main">Kinase</span> Enzyme catalyzing transfer of phosphate groups onto specific substrates

In biochemistry, a kinase is an enzyme that catalyzes the transfer of phosphate groups from high-energy, phosphate-donating molecules to specific substrates. This process is known as phosphorylation, where the high-energy ATP molecule donates a phosphate group to the substrate molecule. This transesterification produces a phosphorylated substrate and ADP. Conversely, it is referred to as dephosphorylation when the phosphorylated substrate donates a phosphate group and ADP gains a phosphate group. These two processes, phosphorylation and dephosphorylation, occur four times during glycolysis.

<span class="mw-page-title-main">Cyclin-dependent kinase</span> Class of enzymes

Cyclin-dependent kinases (CDKs) are the families of protein kinases first discovered for their role in regulating the cell cycle. They are also involved in regulating transcription, mRNA processing, and the differentiation of nerve cells. They are present in all known eukaryotes, and their regulatory function in the cell cycle has been evolutionarily conserved. In fact, yeast cells can proliferate normally when their CDK gene has been replaced with the homologous human gene. CDKs are relatively small proteins, with molecular weights ranging from 34 to 40 kDa, and contain little more than the kinase domain. By definition, a CDK binds a regulatory protein called a cyclin. Without cyclin, CDK has little kinase activity; only the cyclin-CDK complex is an active kinase but its activity can be typically further modulated by phosphorylation and other binding proteins, like p27. CDKs phosphorylate their substrates on serines and threonines, so they are serine-threonine kinases. The consensus sequence for the phosphorylation site in the amino acid sequence of a CDK substrate is [S/T*]PX[K/R], where S/T* is the phosphorylated serine or threonine, P is proline, X is any amino acid, K is lysine, and R is arginine.

A mitogen-activated protein kinase is a type of protein kinase that is specific to the amino acids serine and threonine. MAPKs are involved in directing cellular responses to a diverse array of stimuli, such as mitogens, osmotic stress, heat shock and proinflammatory cytokines. They regulate cell functions including proliferation, gene expression, differentiation, mitosis, cell survival, and apoptosis.

In cell biology, Protein kinase C, commonly abbreviated to PKC (EC 2.7.11.13), is a family of protein kinase enzymes that are involved in controlling the function of other proteins through the phosphorylation of hydroxyl groups of serine and threonine amino acid residues on these proteins, or a member of this family. PKC enzymes in turn are activated by signals such as increases in the concentration of diacylglycerol (DAG) or calcium ions (Ca2+). Hence PKC enzymes play important roles in several signal transduction cascades.

<span class="mw-page-title-main">Serine/threonine-specific protein kinase</span> Class of protein kinase enzymes

A serine/threonine protein kinase is a kinase enzyme, in particular a protein kinase, that phosphorylates the OH group of the amino-acid residues serine or threonine, which have similar side chains. At least 350 of the 500+ human protein kinases are serine/threonine kinases (STK).

<span class="mw-page-title-main">Protein kinase domain</span>

The protein kinase domain is a structurally conserved protein domain containing the catalytic function of protein kinases. Protein kinases are a group of enzymes that move a phosphate group onto proteins, in a process called phosphorylation. This functions as an on/off switch for many cellular processes, including metabolism, transcription, cell cycle progression, cytoskeletal rearrangement and cell movement, apoptosis, and differentiation. They also function in embryonic development, physiological responses, and in the nervous and immune system. Abnormal phosphorylation causes many human diseases, including cancer, and drugs that affect phosphorylation can treat those diseases.

<span class="mw-page-title-main">MAP2K7</span> Protein-coding gene in the species Homo sapiens

Dual specificity mitogen-activated protein kinase kinase 7, also known as MAP kinase kinase 7 or MKK7, is an enzyme that in humans is encoded by the MAP2K7 gene. This protein is a member of the mitogen-activated protein kinase kinase family. The MKK7 protein exists as six different isoforms with three possible N-termini and two possible C-termini.

<span class="mw-page-title-main">Protein phosphorylation</span> Process of introducing a phosphate group on to a protein

Protein phosphorylation is a reversible post-translational modification of proteins in which an amino acid residue is phosphorylated by a protein kinase by the addition of a covalently bound phosphate group. Phosphorylation alters the structural conformation of a protein, causing it to become either activated or deactivated, or otherwise modifying its function. Approximately 13000 human proteins have sites that are phosphorylated.

The Akt signaling pathway or PI3K-Akt signaling pathway is a signal transduction pathway that promotes survival and growth in response to extracellular signals. Key proteins involved are PI3K and Akt.

<span class="mw-page-title-main">MYLK4</span>

Myosin light chain kinase 4 also known as MYLK4 is an enzyme which in humans is encoded by the MYLK2 gene. MYLK4 is a member of the myosin light-chain kinase family of serine/threonine-specific protein kinases that phosphorylate the regulatory light chain of myosin II.

<span class="mw-page-title-main">Autophosphorylation</span>

Autophosphorylation is a type of post-translational modification of proteins. It is generally defined as the phosphorylation of the kinase by itself. In eukaryotes, this process occurs by the addition of a phosphate group to serine, threonine or tyrosine residues within protein kinases, normally to regulate the catalytic activity. Autophosphorylation may occur when a kinases' own active site catalyzes the phosphorylation reaction, or when another kinase of the same type provides the active site that carries out the chemistry. The latter often occurs when kinase molecules dimerize. In general, the phosphate groups introduced are gamma phosphates from nucleoside triphosphates, most commonly ATP.

<span class="mw-page-title-main">Phosphomimetics</span> Amino acid substitutions that mimic a phosphorylated protein

Phosphomimetics are amino acid substitutions that mimic a phosphorylated protein, thereby activating the protein. Within cells, proteins are commonly modified at serine, tyrosine and threonine amino acids by adding a phosphate group. Phosphorylation is a common mode of activating or deactivating a protein as a form of regulation. However some non-phosphorylated amino acids appear chemically similar to phosphorylated amino acids. Therefore, by replacing an amino acid, the protein may maintain a higher level of activity. For example, aspartic acid is chemically similar to phospho-serine. Therefore, when an aspartic acid replaces a serine, it is a phosphomimetic of phospho-serine and can make the protein always in its phosphorylated form. Phosphonate-based compounds have been used as phosphotyrosine analogues, as they are less enzyme labile and are physiologically more stable.

The phosphatome of an organism is the set of phosphatase genes in its genome. Phosphatases are enzymes that catalyze the removal of phosphate from biomolecules. Over half of all cellular proteins are modified by phosphorylation which typically controls their functions. Protein phosphorylation is controlled by the opposing actions of protein phosphatases and protein kinases. Most phosphorylation sites are not linked to a specific phosphatase, so the phosphatome approach allows a global analysis of dephosphorylation, screening to find the phosphatase responsible for a given reaction, and comparative studies between different phosphatases, similar to how protein kinase research has been impacted by the kinome approach.

<span class="mw-page-title-main">Protein arginine phosphatase</span> Enzyme that catalyzes the dephosphorylation of phosphoarginine residues in proteins

Protein Arginine Phosphatase (PAPs), also known as Phosphoarginine Phosphatase, is an enzyme that catalyzes the dephosphorylation of phosphoarginine residues in proteins. Protein phosphatases (PPs) are "obligatory heteromers" made up of two maximum catalytic subunits attached to a non-catalytic subunit. Arginine modification is a post-translational protein modification in gram-positive bacteria. McsB and YwIE were recently identified as phosphorylating enzymes in Bacillus Subtilis (B.Subtilis). YwIE was thought to be a protein-tyrosine-phosphatase, and McsB a tyrosine-kinase, however in 2012 Elsholz et al. showed that McsB is a protein-arginine-kinase (PAK) and YwlE is a phosphatase-arginine-phosphatase (PAP).

H3S10P is an epigenetic modification to the DNA packaging protein histone H3. It is a mark that indicates the phosphorylation the 10th serine residue of the histone H3 protein.

H3S28P is an epigenetic modification to the DNA packaging protein histone H3. It is a mark that indicates the phosphorylation the 28th serine residue of the histone H3 protein.

H3T11P is an epigenetic modification to the DNA packaging protein histone H3. It is a mark that indicates the phosphorylation the 11th threonine residue of the histone H3 protein.

H3T6P is an epigenetic modification to the DNA packaging protein histone H3. It is a mark that indicates the phosphorylation of the 6th threonine residue of the histone H3 protein.

References

  1. ↑ Manning G, Whyte DB, Martinez R, Hunter T, Sudarsanam S (December 2002). "The protein kinase complement of the human genome". Science. 298 (5600): 1912–34. Bibcode:2002Sci...298.1912M. doi:10.1126/science.1075762. PMID   12471243. S2CID   26554314.
  2. ↑ Manning G, Plowman GD, Hunter T, Sudarsanam S (October 2002). "Evolution of protein kinase signaling from yeast to man". Trends Biochem. Sci. 27 (10): 514–20. doi:10.1016/S0968-0004(02)02179-5. PMID   12368087.
  3. ↑ Dardick C, Chen J, Richter T, Ouyang S, Ronald P (February 2007). "The Rice Kinase Database. A Phylogenomic Database for the Rice Kinome". Plant Physiol. 143 (2): 579–86. doi:10.1104/pp.106.087270. PMC   1803753 . PMID   17172291.
  4. ↑ Bradham CA, Foltz KR, Beane WS, et al. (December 2006). "The sea urchin kinome: a first look". Dev. Biol. 300 (1): 180–93. doi: 10.1016/j.ydbio.2006.08.074 . PMID   17027740.
  5. ↑ Goldberg JM, Manning G, Liu A, et al. (March 2006). "The Dictyostelium Kinome—Analysis of the Protein Kinases from a Simple Model Organism". PLOS Genet. 2 (3): e38. doi: 10.1371/journal.pgen.0020038 . PMC   1420674 . PMID   16596165.
  6. ↑ Hestvik AL, Hmama Z, Av-Gay Y (October 2003). "Kinome Analysis of Host Response to Mycobacterial Infection: a Novel Technique in Proteomics". Infect. Immun. 71 (10): 5514–22. doi:10.1128/IAI.71.10.5514-5522.2003. PMC   201077 . PMID   14500469.
  7. ↑ Reiterer V, Eyers PA, Farhan H (2014). "Day of the dead: pseudokinases and pseudophosphatases in physiology and disease". Trends in Cell Biology. 24 (9): 489–505. doi:10.1016/j.tcb.2014.03.008. PMID   24818526.
  8. ↑ Diks SH, Parikh K, van der Sijde M, Joore J, Ritsema T, Peppelenbosch MP (2007). Insall R (ed.). "Evidence for a Minimal Eukaryotic Phosphoproteome?". PLOS ONE. 2 (1): 777. Bibcode:2007PLoSO...2..777D. doi: 10.1371/journal.pone.0000777 . PMC   1945084 . PMID   17712425.
  9. ↑ Workman P (2005). "Drugging the cancer kinome: progress and challenges in developing personalized molecular cancer therapeutics". Cold Spring Harb. Symp. Quant. Biol. 70: 499–515. doi: 10.1101/sqb.2005.70.020 . PMID   16869789.
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