Editing Kinase (section)

==History and classification==
<!-- Commented out: [[File:Edwin G. Krebs.jpg|thumb|Edwin Krebs won the Nobel prize in physiology or medicine in 1992 for his contributions to enzymology. He described how phosphorylation is reversible and acts a switch to regulate metabolic processes as well as other cellular pathways.]] -->
The first protein to be recognized as catalyzing the phosphorylation of another protein using ATP was observed in 1954 by [[Eugene P. Kennedy]] at which time he described a liver enzyme that catalyzed the phosphorylation of casein.{{cn|date=March 2023}} In 1956, [[Edmond H. Fischer]] and [[Edwin G. Krebs]] discovered that the interconversion between phosphorylase a and phosphorylase b was mediated by phosphorylation and dephosphorylation.<ref>{{cite journal | vauthors = Krebs EG | title = Historical perspectives on protein phosphorylation and a classification system for protein kinases | journal = Philosophical Transactions of the Royal Society of London. Series B, Biological Sciences | volume = 302 | issue = 1108 | pages = 3–11 | date = July 1983 | pmid = 6137005 | doi = 10.1098/rstb.1983.0033 | doi-access = free | bibcode = 1983RSPTB.302....3K }}</ref> The kinase that transferred a phosphoryl group to Phosphorylase b, converting it to Phosphorylase a, was named Phosphorylase Kinase. Years later, the first example of a kinase cascade was identified, whereby Protein Kinase A (PKA) phosphorylates Phosphorylase Kinase. At the same time, it was found that PKA inhibits [[glycogen synthase]], which was the first example of a phosphorylation event that resulted in inhibition. In 1969, Lester Reed discovered that [[pyruvate dehydrogenase]] was inactivated by phosphorylation, and this discovery was the first clue that phosphorylation might serve as a means of regulation in other metabolic pathways besides [[glycogen]] metabolism. In the same year, Tom Langan discovered that PKA phosphorylates histone H1, which suggested phosphorylation might regulate nonenzymatic proteins. The 1970s included the discovery of [[Ca2+/calmodulin-dependent protein kinase|calmodulin-dependent protein kinases]] and the finding that proteins can be phosphorylated on more than one amino acid residue. The 1990s may be described as the "decade of protein kinase cascades". During this time, the [[MAPK/ERK pathway]], the [[janus kinase|JAK kinases]] (a family of protein tyrosine kinases), and the PIP3-dependent kinase cascade were discovered.<ref name=origins>{{cite journal | vauthors = Corbellino M, Poirel L, Aubin JT, Paulli M, Magrini U, Bestetti G, Galli M, Parravicini C | display-authors = 6 | title = The role of human herpesvirus 8 and Epstein-Barr virus in the pathogenesis of giant lymph node hyperplasia (Castleman's disease) | journal = Clinical Infectious Diseases | volume = 22 | issue = 6 | pages = 1120–1121 | date = June 1996 | pmid = 8783733 | doi = 10.1093/clinids/22.6.1120 | doi-access = free }}</ref>

Kinases are classified into broad groups by the substrate they act upon: protein kinases, lipid kinases, carbohydrate kinases. Kinases can be found in a variety of species, from bacteria to mold to worms to mammals.<ref>{{cite journal | vauthors = Scheeff ED, Bourne PE | title = Structural evolution of the protein kinase-like superfamily | journal = PLOS Computational Biology | volume = 1 | issue = 5 | pages = e49 | date = October 2005 | pmid = 16244704 | pmc = 1261164 | doi = 10.1371/journal.pcbi.0010049 | bibcode = 2005PLSCB...1...49S | doi-access = free }}</ref> More than five hundred different protein kinases have been identified in humans.<ref name="pmid12471243" /> Their diversity and their role in signaling makes them an interesting object of study. Various other kinases act on small molecules such as [[lipid]]s, [[carbohydrate]]s, [[amino acid]]s, and [[nucleotide]]s, either for signaling or to prime them for metabolic pathways. Specific kinases are often named after their substrates. Protein kinases often have multiple substrates, and proteins can serve as substrates for more than one specific kinase. For this reason protein kinases are named based on what regulates their activity (i.e. Calmodulin-dependent protein kinases). Sometimes they are further subdivided into categories because there are several isoenzymatic forms. For example, type I and type II cyclic-AMP dependent protein kinases have identical catalytic subunits but different regulatory subunits that bind cyclic AMP.<ref name="krebs lec">{{cite journal | vauthors = Krebs EG | title = The phosphorylation of proteins: a major mechanism for biological regulation. Fourteenth Sir Frederick Gowland Hopkins memorial lecture | journal = Biochemical Society Transactions | volume = 13 | issue = 5 | pages = 813–820 | date = October 1985 | pmid = 2998902 | doi = 10.1042/bst0130813 }}</ref>