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Catalytic Site Atlas

CSA LITERATURE entry for 1stc

E.C. namecAMP-dependent protein kinase
SpeciesBos taurus (Bovine)
E.C. Number (IntEnz)
CSA Homologues of 1stcThere are 1063 Homologs
CSA Entries With UniProtID P00517
CSA Entries With EC Number
PDBe Entry 1stc
PDBSum Entry 1stc
MACiE Entry 1stc

Literature Report

IntroductionCyclic adenosine 3',5'-monophosphate (cAMP) dependent protein kinase from Bos taurus catalyses the transfer of the gamma phosphate from ATP to a protein. This enzyme can phosphorylate a number of different proteins, one of which being the 70-kDa heat-shock protein (Hsp70). This results in the deactivation of Hsp70. Due to their key role in cellular signalling, defects in protein kinases are often associated with cancer and other diseases.
Mechansim1. Asp 166 activates the phosphoacceptor, causing it to nucleophilically attack the gamma phosphorus of ATP, creating a pentavalent transition state. 2. This transition state is stabilised by Lys 168 hydrogen bonding to it, and also possibly by the backbone amide of Ser 53, although this is not confirmed. 3. Once the gamma phosphoryl transfer has taken place, Asp 166 accepts a proton from the phosphoacceptor. 4. Asp 166 is stabilised by a hydrogen bond to its carboxylate O delta 1 from Thr 201. 5. The proton accepted by Asp 166 is then most likely transferred back to the product ADP.

Catalytic Sites for 1stc

Annotated By Reference To The Literature - Site 3 (Perform Site Search)
ResidueChainNumberUniProtKB NumberFunctional PartFunctionTargetDescription
ThrE201202macie:sideChainStabilises Asp 166 by hydrogen bonding to its carboxylate O delta 1 atom. This only occurs once the substrate is bound.
AspE166167macie:sideChainActs as a 'proton trap', activating the phosphoacceptor and accepting a proton from it once phosphoryl transfer has taken place.
LysE168169macie:sideChainStabilises the transition state by hydrogen bonding to the beta-gamma bridging oxygen atom.

Literature References

Notes:1. Ser 53 may also act to stabilise the transition state, as it is conserved, and in the right place. However, mutation does not affect the phosphoryl transfer rate. 2. There are also 2 metal ions which help to stabilise the transition state. 3. It is not clear whether Asp 166 abstracts a proton during phosphoryl transfer, or after it. Most information points towards the 'proton trap' function as described here.
Yang J
Crystal structure of a cAMP-dependent protein kinase mutant at 1.26A: new insights into the catalytic mechanism.
J Mol Biol 2004 336 473-487
PubMed: 14757059