Delineation of Type I Protein Kinase A-selective Signaling Events Using an RI Anchoring Disruptor

Cathrine Rein Carlson,Birgitte Lygren,Torunn Berge,Naoto Hoshi,Wei Wong,Kjetil Taskén,John D Scott

doi:10.1074/jbc.m603223200

Cathrine Rein Carlson, Birgitte Lygren + Show 5 more

Open Access

https://doi.org/10.1074/jbc.m603223200

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Abstract

Control of specificity in cAMP signaling is achieved by A-kinase anchoring proteins (AKAPs), which assemble cAMP effectors such as protein kinase A (PKA) into multiprotein signaling complexes in the cell. AKAPs tether the PKA holoenzymes at subcellular locations to favor the phosphorylation of selected substrates. PKA anchoring is mediated by an amphipathic helix of 14-18 residues on each AKAP that binds to the R subunit dimer of the PKA holoenzymes. Using a combination of bioinformatics and peptide array screening, we have developed a high affinity-binding peptide called RIAD (RI anchoring disruptor) with >1000-fold selectivity for type I PKA over type II PKA. Cell-soluble RIAD selectively uncouples cAMP-mediated inhibition of T cell function and inhibits progesterone synthesis at the mitochondria in steroid-producing cells. This study suggests that these processes are controlled by the type I PKA holoenzyme and that RIAD can be used as a tool to define anchored type I PKA signaling events.

Highlights

Oddrun Mjålands Stiftelse, National Institutes of Health Grant DK54441, Heart and Stroke Foundation of Canada, The National Programme for Research in Functional Genomics in Norway (FUGE), The Research Council of Norway (MEDKAP), Birkeland Innovation AS, and European Union RTD Grant QLK3-CT-2002-02149
We report the development of the RI␣-specific anchoring peptide, RIAD, an 18-amino acid peptide that displays a 3 orders of magnitude selectivity of binding to type I protein kinase A (PKA) over type II PKA
RIAD binds type I with a higher affinity than any natural A-kinase anchoring proteins (AKAPs) or other anchoring disruption peptides published so far

Summary

Introduction

Oddrun Mjålands Stiftelse, National Institutes of Health Grant DK54441, Heart and Stroke Foundation of Canada, The National Programme for Research in Functional Genomics in Norway (FUGE), The Research Council of Norway (MEDKAP), Birkeland Innovation AS, and European Union RTD Grant QLK3-CT-2002-02149. Detection of phosphorylated RI␣ (A98S) binding with the PDSM sequence and other immobilized AKAP-derived peptides was assessed by autoradiography (Fig. 1B). This suggests that RIAD is 20-fold more selective for RI␣ than PV-38, a peptide derived from the dual specificity anchoring protein D-AKAP1 (21).

Results

Conclusion