Published In

eLife

Document Type

Article

Publication Date

11-2013

Subjects

Protein kinases, Phosphorylation, Cellular control mechanisms, Electron microscopy, Proteins -- Conformation

Abstract

Anchoring proteins sequester kinases with their substrates to locally disseminate intracellular signals and avert indiscriminate transmission of these responses throughout the cell. Mechanistic understanding of this process is hampered by limited structural information on these macromolecular complexes. A-kinase anchoring proteins (AKAPs) spatially constrain phosphorylation by cAMP-dependent protein kinases (PKA). Electron microscopy and three-dimensional reconstructions of type-II PKA-AKAP18γ complexes reveal hetero-pentameric assemblies that adopt a range of flexible tripartite configurations. Intrinsically disordered regions within each PKA regulatory subunit impart the molecular plasticity that affords an ∼16 nanometer radius of motion to the associated catalytic subunits. Manipulating flexibility within the PKA holoenzyme augmented basal and cAMP responsive phosphorylation of AKAP-associated substrates. Cell-based analyses suggest that the catalytic subunit remains within type-II PKA-AKAP18γ complexes upon cAMP elevation. We propose that the dynamic movement of kinase sub-structures, in concert with the static AKAP-regulatory subunit interface, generates a solid-state signaling microenvironment for substrate phosphorylation.

Description

Originally appeared in eLife, published by elife.elifesciences.org. © Smith et al.

Note: At the time of writing, Steve Reichow was affiliated with the Howard Hughes Medical Institute, University of Washington, Seattle.

DOI

10.7554/eLife.01319

Persistent Identifier

http://archives.pdx.edu/ds/psu/21410

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