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| Titel | Serine/threonine-specific protein kinase |
| Verlag | (Wikipedia) |
| Datum | 29. September 2006 |
| URL | http://en.wikipedia.org/w/index.php?title=Serine/threonine-specific_protein_kinase&oldid=78434629 |
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| Fußnoten | no |
| Fragmente | 3 |
| [1.] Dsa/Fragment 018 20 - Diskussion Zuletzt bearbeitet: 2016-08-07 10:17:04 WiseWoman | Dsa, Fragment, Gesichtet, SMWFragment, Schutzlevel sysop, Verschleierung, Wikipedia Serine-threonine-specific protein kinase 2006 |
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| Untersuchte Arbeit: Seite: 18, Zeilen: 20-39 |
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| 1) Serine/threonine-specific protein kinases
Serine/threonine protein kinases phosphorylate the -OH group of serine or threonine (which has similar sidechains). Activity of these protein kinases can be regulated by specific events (e.g. DNA damage), as well as numerous chemical signals, including cAMP/cGMP, diacylglycerol, and Ca2+/calmodulin. These kinases are not specific to a similar consensus sequence - that is there is no common "target sequence" to be phosphorylated. Since the substrate to be phosphorylated aligns with the kinase by several key amino acids (usually through hydrophopic forces and ionic bonds), a kinase is usually specific, not to a single substrate, but to a whole "substrate family" having common properties. The kinases are usually inactivated by a pseudosubstrate that binds to the kinase like a real substrate but lacks the amino acid to be phosphorylated. Its removal activates the kinase. The catalytic domain of these kinases is highly conserved. - Phosphorylase kinase: phosphorylase kinase was the first Ser/Thr protein kinase to be discovered (Krebs EG et al., (1959) J Biol Chem). - Protein kinase A: protein kinase A consists of two domains, a small domain with several β sheet structures and a larger domain containing several α helices. The binding sites for substrate and ATP are located in the catalytic cleft between the domains (or lobes). When ATP and substrate bind, the two lobes rotate so that the terminal phosphate group of the ATP and the target amino acid of the substrate move into the correct positions for the catalytic reaction to take place. |
Serine/threonine-specific protein kinase
[...] Serine/threonine protein kinases (EC 2.7.11.1) phosphorylate the OH group of serine or threonine (which have similar sidechains). Activity of these protein kinases can be regulated by specific events (e.g. DNA damage), as well as numerous chemical signals, including:
While serine/threonine kinases all phosphorylate serine or threonine residues in their substrates, they select specific residues to phosphorylate on the basis of residues that flank the phosphoacceptor site, which together comprise the consensus sequence. Since the consensus sequence residues of the substrate to be phosphorylated make contact with the catalytic cleft of the kinase at several key amino acids (usually through hydrophobic forces and ionic bonds), a kinase is usually not specific to a single substrate, but instead can phosphorylate a whole "substrate family" having common recognition sequences. While the catalytic domain of these kinases is highly conserved, the sequence variation that is observed in the kinome (the subset of genes in the genome that encode kinases) provides for recognition of distinct substrates. Most kinases are inhibited by a pseudosubstrate that binds to the kinase like a real substrate but lacks the amino acid to be phosphorylated. When the pseudosubstrate is removed, the kinase can perform its normal function. [...] Phosphorylase kinase Phosphorylase kinase (EC 2.7.11.19) was in fact, the first Ser/Thr protein kinase to be discovered (in 1959 by Krebs et al.). Protein kinase A [...] Protein kinase A (EC 2.7.11.1) consists of two domains, a small domain with several β sheet structures and a larger domain containing several α helices. The binding sites for substrate and ATP are located in the catalytic cleft between the domains (or lobes). When ATP and substrate bind, the two lobes rotate so that the terminal phosphate group of the ATP and the target amino acid of the substrate move into the correct positions for the catalytic reaction to take place. |
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| [2.] Dsa/Fragment 019 35 - Diskussion Zuletzt bearbeitet: 2016-08-02 19:12:17 WiseWoman | Dsa, Fragment, Gesichtet, KomplettPlagiat, SMWFragment, Schutzlevel sysop, Wikipedia Serine-threonine-specific protein kinase 2006 |
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| Untersuchte Arbeit: Seite: 19, Zeilen: 35-42 |
Quelle: Wikipedia Serine-threonine-specific protein kinase 2006 Seite(n): 1 (online source), Zeilen: - |
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| Ca2+/calmodulin-dependent protein kinases:
Also called CaM kinases, these kinases are primarily regulated by the Ca2+/calmodulin complex. These kinases show a memory effect on activation. Two types of CaM kinases are: • Specialized CaM kinases. An example is the myosin light chain kinase (MLCK) that phosphorylates myosin, causing muscles to contract. • Multifunctional CaM kinases. Also collectively called CaM kinase II, which play a role in many processes, such as neurotransmitter secretion, transcription factor regulation, and glycogen metabolism. |
Ca2+/calmodulin-dependent protein kinases
Also called CaM kinases (EC 2.7.11.17), these kinases are primarily regulated by the Ca2+/calmodulin complex. These kinases show a memory effect on activation. Two types of CaM kinases are: • Specialized CaM kinases. An example is the myosin light chain kinase (MLCK) that phosphorylates myosin, causing muscles to contract. • Multifunctional CaM kinases. Also collectively called CaM kinase II, which play a role in many processes, such as neurotransmitter secretion, transcription factor regulation, and glycogen metabolism. |
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| [3.] Dsa/Fragment 020 01 - Diskussion Zuletzt bearbeitet: 2016-08-02 19:24:22 WiseWoman | Dsa, Fragment, Gesichtet, KomplettPlagiat, SMWFragment, Schutzlevel sysop, Wikipedia Serine-threonine-specific protein kinase 2006 |
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| Untersuchte Arbeit: Seite: 20, Zeilen: 1-13 |
Quelle: Wikipedia Serine-threonine-specific protein kinase 2006 Seite(n): 1 (online source), Zeilen: - |
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| Structure and autoregulation
The CaM kinases consist of an N-terminal catalytic domain, a regulatory domain and an associative domain. In the absence of Ca2+/calmodulin, the catalytic domain is auto inhibited by the regulatory domain, which contains a pseudo substrate sequence. Several CaM kinases aggregate into a homo-oligomer or hetero-oligomer. Upon activation by Ca2+/calmodulin, the activated CaM kinases autophosphorylate each other, in an intermolecular reaction. This has two effects: • An increase in affinity for the calmodulin complex, prolonging the time the kinase is active. • Continued activation of the phosphorylated kinase complex even after the calmodulin complex has dissociated from the kinase complex, which prolongs the active state even more. |
Structure and autoregulation
The CaM kinases consist of an N-terminal catalytic domain, a regulatory domain, and an association domain. In the absence of Ca2+/calmodulin, the catalytic domain is autoinhibited by the regulatory domain, which contains a pseudosubstrate sequence. Several CaM kinases aggregate into a homooligomer or heterooligomer. Upon activation by Ca2+/calmodulin, the activated CaM kinases autophosphorylate each other in an intermolecular reaction. This has two effects: 1. An increase in affinity for the calmodulin complex, prolonging the time the kinase is active. 2. Continued activation of the phosphorylated kinase complex even after the calmodulin complex has dissociated from the kinase complex, which prolongs the active state even more. |
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