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.
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.
In cell biology, protein kinase A (PKA) is a family of serine-threonine kinase whose activity is dependent on cellular levels of cyclic AMP (cAMP). PKA is also known as cAMP-dependent protein kinase. PKA has several functions in the cell, including regulation of glycogen, sugar, and lipid metabolism. It should not be confused with 5'-AMP-activated protein kinase.
ADF/cofilin is a family of actin-binding proteins associated with the rapid depolymerization of actin microfilaments that give actin its characteristic dynamic instability. This dynamic instability is central to actin's role in muscle contraction, cell motility and transcription regulation.
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).
The IκB kinase is an enzyme complex that is involved in propagating the cellular response to inflammation, specifically the regulation of lymphocytes.
In enzymology, a [3-methyl-2-oxobutanoate dehydrogenase (acetyl-transferring)] is an enzyme that catalyzes the chemical reaction
In enzymology, a [acetyl-CoA carboxylase] kinase is an enzyme that catalyzes the chemical reaction
In enzymology, a beta-adrenergic-receptor kinase is an enzyme that catalyzes the chemical reaction:
In enzymology, a dephospho-[reductase kinase] kinase is an enzyme that catalyzes the chemical reaction
In enzymology, an elongation factor 2 kinase is an enzyme that catalyzes the chemical reaction:
In enzymology, a Goodpasture-antigen-binding protein kinase is an enzyme that catalyzes the chemical reaction
In enzymology, a [isocitrate dehydrogenase (NADP+)] kinase (EC 2.7.11.5) is an enzyme that catalyzes the chemical reaction:
In enzymology, a low-density-lipoprotein receptor kinase is an enzyme that catalyzes the chemical reaction
In enzymology, a myosin-heavy-chain kinase is an enzyme that catalyzes the chemical reaction
In enzymology, a Fas-activated serine/threonine kinase is an enzyme that catalyzes the chemical reaction
In enzymology, a polo kinase is a kinase enzyme i.e. one that catalyzes the chemical reaction
In enzymology, an [RNA-polymerase]-subunit kinase is an enzyme that catalyzes the chemical reaction
In enzymology, a tau-protein kinase is an enzyme that catalyzes the chemical reaction
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.
