Catalytic subunit dimer complexed with PKI(5-24), 5-adenyl y-imido triphosphate, 2(Mn++) myristilated. Porcine heart. Phosphorylated. Resolution 2.0A Closed conformation
The crystal structure of the porcine heart catalytic subunit of cAMP-dependent protein kinase in a ternary complex with
the MgATP analogue MnAMP-PNP and a pseudosubstrate inhibitor peptide, PKI(5-24), has been solved at 2.0 A
resolution from monoclinic crystals of the catalytic subunit isoform CA. The refinement is presently at an R factor of
0.194 and the active site of the molecule is well defined. The glycine-rich phosphate anchor of the nucleotide binding fold
motif of the protein kinase is a beta ribbon acting as a flap with conformational flexibility over the triphosphate group.
The glycines seem to be conserved to avoid steric clash with ATP. The known synergistic effects of substrate binding can
be explained by hydrogen bonds present only in the ternary complex. Implications for the kinetic scheme of binding order
are discussed. The structure is assumed to represent a phosphotransfer competent conformation. The invariant conserved
residue Asp166 is proposed to be the catalytic base and Lys168 to stabilize the transition state. In some tyrosine kinases
Lys168 is functionally replaced by an Arg displaced by two residues in the primary sequence, suggesting invariance in
three-dimensional space. The structure supports an in-line transfer with a pentacoordinate transition state at the
phosphorus with very few nuclear movements.
 Bossemeyer D; Engh RA; Kinzel V; Postingl H; Huber R (1993)
Phosphotransferase and substrate binding mechanism of the cAMP-dependent
protein kinase catalytic subunit from porcine heart as deduced from the
2.0 A structure of the complex with Mn2+ adenylyl imidodiphosphate and
inhibitor peptide PKI(5-24). EMBO J12(3): 849-859.
 Bossemeyer, D (1995) FEBS Lett 369: 57-61. Protein kinases--structure and function.
 Bossemeyer, D (1994) Trends Biochem Sci 19: 201-5.
The glycine-rich sequence of protein kinases: a multifunctional
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