Papers In Press, published online ahead of print September 7, 2007
J. Biol. Chem, 10.1074/jbc.M705167200
Submitted on June 22, 2007
Revised on August 28, 2007
Accepted on September 7, 2007
MyRIP anchors protein kinase A to the exocyst complex
April S. Goehring, Benjamin S. Pedroja, Simon A. Hinke, Lorene K. Langeberg, and John D. Scott
Howard Hughes Medical Institute, Vollum Institute, Oregon Health & Science University, Portland, OR 97239
Corresponding Author: scott{at}ohsu.edu
The movement of signal transduction enzymes in and out of multi-protein complexes coordinates the spatial and temporal resolution of cellular events. Anchoring and scaffolding proteins are key to this process as they sequester protein kinases and phosphatases with a subset of their preferred substrates. The A-kinase anchoring family of proteins (AKAPs), which target the cAMP-dependent protein kinase (PKA) and other enzymes to defined subcellular microenvironments, represent a well-studied group of these signal-organizing molecules. In this report we demonstrate that the Rab27a GTPase effector protein MyRIP is a member of the AKAP family. The zebrafish homolog of MyRIP (Ze-AKAP2) was initially detected in a two-hybrid screen for AKAPs. A combination of biochemical, cell-based and immunofluorescence approaches demonstrate that the mouse MyRIP ortholog targets the type II PKA holoenzyme via an atypical mechanism to a specific perinuclear region of insulin-secreting cells. Similar approaches show that MyRIP interacts with the Sec6 and Sec8 components of the exocyst complex, an evolutionarily conserved protein unit that controls protein trafficking and exocytosis. These data indicate that MyRIP functions as a scaffolding protein that links PKA to components of the exocytosis machinery.