4NTT: Structure Of The Catalytic Subunit Of Camp-dependent Protein Kinase Bound To Adp And One Magnesium Ion

Although ADP release is the rate limiting step in product turnover by protein kinase A, the steps and motions involved in this process are not well resolved. Here we report the apo and ADP bound structures of the myristylated catalytic subunit of PKA at 2.9 and 3.5 A resolution, respectively. The ADP bound structure adopts a conformation that does not conform to the previously characterized open, closed, or intermediate states. In the ADP bound structure, the C-terminal tail and Gly-rich loop are more closed than in the open state adopted in the apo structure but are also much more open than the intermediate or closed conformations. Furthermore, ADP binds at the active site with only one magnesium ion, termed Mg2 from previous structures. These structures thus support a model where ADP release proceeds through release of the substrate and Mg1 followed by lifting of the Gly-rich loop and disengagement of the C-terminal tail. Coupling of these two structural elements with the release of the first metal ion fills in a key step in the catalytic cycle that has been missing and supports an ensemble of correlated conformational states that mediate the full catalytic cycle for a protein kinase.
PDB ID: 4NTTDownload
MMDB ID: 123815
PDB Deposition Date: 2013/12/2
Updated in MMDB: 2014/10
Experimental Method:
x-ray diffraction
Resolution: 3.5  Å
Source Organism:
Similar Structures:
Biological Unit for 4NTT: monomeric; determined by author and by software (PISA)
Molecular Components in 4NTT
Label Count Molecule
Protein (1 molecule)
Camp-dependent Protein Kinase Catalytic Subunit Alpha(Gene symbol: Prkaca)
Molecule annotation
Chemicals (2 molecules)
* Click molecule labels to explore molecular sequence information.

Citing MMDB