title: Discovery of Allostery in PKA Signaling.
abstract: cAMP-dependent protein kinase (PKA) was the second protein kinase to be discovered and the PKA catalytic (C) subunit serves as a prototype for the large protein kinase superfamily that contains over 500 gene products. The protein kinases regulate much of biology in eukaryotic cells and they are now also a major therapeutic target. Although PKA was discovered nearly 50 years ago and the subsequent discovery of the regulatory subunits that bind cAMP and release the catalytic activity from the holoenzyme followed quickly. Thus in PKA we see the convergence of two major signaling mechanisms - protein phosphorylation and second messenger signaling through cAMP. Crystallography provides a foundation for understanding function, and the structure of the isolated regulatory (R) and C-subunits have been extremely informative. Yet it is the R2C2holoenzyme that predominates in cells, and one can only appreciate the allosteric features of PKA signaling by seeing the full length protein. The symmetry and the quaternary constraints that one R:C hetero-dimer exerts on the other in the holoenzyme simply are not present in the isolated subunits or even in the R:C hetero-dimer.
authors.affiliation: Department of Pharmacology, University of California at San Diego, La Jolla, California 92093.
authors.forename: Ping
authors.initials: P
authors.lastname: Zhang
authors.affiliation: Department of Pharmacology, University of California at San Diego, La Jolla, California 92093.
authors.forename: Alexandr P
authors.initials: AP
authors.lastname: Kornev
authors.affiliation: Department of Pharmacology, University of California at San Diego, La Jolla, California 92093.
authors.forename: Jian
authors.initials: J
authors.lastname: Wu
authors.affiliation: Department of Pharmacology, University of California at San Diego, La Jolla, California 92093 ; Department of Chemistry and Biochemistry, University of California at San Diego, La Jolla, California 92093.
authors.forename: Susan S
authors.initials: SS
authors.lastname: Taylor
keywords: Allostery; Cyclic AMP (cAMP); PKA Regulatory (R) Subunit; PKA catalytic (C) subunit; cAMP-dependent protein kinase (PKA)