Dual-specificity A-kinase anchoring proteins (AKAPs) contain an additional binding region that enhances targeting of PKA type I

Jarnaess E, Ruppelt A, Stokka AJ, Lygren B, Scott JD, Tasken K
Source: J Biol Chem
Publication Date: (2008)
Issue: epub: online
Research Area:
Immunotherapy / Hematology
Cells used in publication:
T cell, human peripheral blood unstim.
Species: human
Tissue Origin: blood
Nucleofector® I/II/2b
A-kinase anchoring proteins (AKAPs) target Protein Kinase A (PKA) to a variety of subcellular locations. Conventional AKAPs contain a 14-18 amino acid sequence that forms an amphipathic helix that binds with high affinity to the regulatory (R) subunit of PKA type II. More recently a group of dual-specificity AKAPs has been classified on the basis of their ability to bind the PKA type I and the PKA type II isozymes. In this report we show that dual-specificity AKAPs contain an additional PKA-binding determinant called the RI Specifier Region (RISR). A variety of protein interaction assays, immunoprecipitation and immunolocalization experiments indicate that the RISR augments RI-binding in vitro and inside cells. Cellular delivery of the RISR peptide uncouples RI anchoring to Ezrin leading to release of T cell inhibition by cAMP. Likewise, expression of mutant Ezrin forms where RI-binding has been abrogated by substitution of the RISR sequence prevents cAMP mediated inhibition of T cell function. Thus, we propose that the RISR acts in synergy with the amphipathic helix in dual-specificity anchoring proteins to enhance anchoring of PKA type I.