Kinase
Kinase | ||
---|---|---|
Enzyme classification | ||
EC, category | 2.7.-.- , transferase | |
Response type | Phosphorylation | |
Products | Phospho substrate |
Kinases are enzymes that transfer a phosphate residue from a nucleoside triphosphate (e.g. ATP ) to other substrates, there in particular through reaction with hydroxyl groups (-OH) and vice versa. They can be activated by other molecules (e.g. enzymes). In addition to aminotransferases and glycosyl transferases, kinases belong to the class of transferases . According to the EC number classification system, they belong to group EC 2.7.
In the history of biochemistry , the term “kinase” was used broadly. Enzymes were also called kinases, which convert zymogens into enzymes . One example is the classic enterokinase, which is now called enteropeptidase .
Kinases in the sugar metabolism
A group of kinases phosphorylates hydroxyl groups on sugar molecules . These can be found u. a. in both phases of glycolysis
- in the "collection phase" (phosphorylation of glucose and conversion into glyceraldehyde-3-phosphate with consumption of ATP): hexokinase or glucokinase and phosphofructokinase
- In the "gain phase" (conversion of glyceraldehyde-3-phosphate to pyruvate with ATP formation): phosphoglycerate kinase and pyruvate kinase , two enzymes that are involved in the formation of ATP from phosphorylated metabolites ( 1,3-bisphosphoglycerate or phosphoenolpyruvate ). In the sense of a “backward reaction”, a phosphate residue is transferred from a metabolite with a high group transfer potential to ADP .
Protein kinases
Main article: Protein kinase
Further acceptor groups for kinases are the alcoholic amino acid residues of proteins. The modifying enzymes, protein kinases , are the second most common class of proteins in higher cells. They are classified either according to the type of modified group ( serine , threonine , tyrosine ) or according to their activation mechanism (e.g. protein kinase A , protein kinase B (see insulin / cellular effects), protein kinase C , protein kinase G ). The effect of these kinases can be reversed by specialized protein phosphatases .
Multifunctional Kinases
Some kinases phosphorylate metabolites as well as other proteins. Thus, the phosphoglycerate kinase 1 (PGK1) phosphorylates both 3- phosphoglycerate (by means of ATP) to 1,3-diphosphoglycerate and at least 3 proteins, e.g. B. Beclin 1 (involved in autophagy ), PDHK1 (pyruvate metabolism), and Bcl2 ( apoptosis ).
See also
Web links
Individual evidence
- ↑ Zhimin Lu, Tony Hunter: Metabolic Kinases Moonlighting as Protein Kinases . In: Trends in Biochemical Sciences . tape 43 , no. 4 , April 2018, ISSN 0968-0004 , p. 301-310 , doi : 10.1016 / j.tibs.2018.01.006 , PMID 29463470 , PMC 5879014 (free full text) - ( elsevier.com [accessed on July 22, 2018]).