Date of Completion

4-27-2017

Embargo Period

4-26-2017

Keywords

A Kinase Anchoring Protein, AKAP, Protein Kinase A, PKA, Langevin dynamics, phospholamban, PLB, phosphorylation, oligomerization, photon counting histogram, cyclic AMP, cAMP

Major Advisor

Kim Dodge-Kafka

Co-Major Advisor

Ion Moraru

Associate Advisor

Ann Cowan

Associate Advisor

John Carson

Associate Advisor

Yi Wu

Field of Study

Biomedical Science

Degree

Doctor of Philosophy

Open Access

Open Access

Abstract

In the cell, cAMP-protein kinase A (PKA) signaling is compartmentalized. Two different receptor types, both utilizing cAMP and PKA as second messenger and signal effector, are able to convey separate signals that result in phosphorylation of distinct substrates. Signal compartmentation is possible primarily because of A Kinase Anchoring Proteins (AKAPs) that bind both PKA and a target substrate, effectively co-localizing them. AKAPs are also capable of binding to other necessary signaling components like adenylate cyclase and phosphodiesterase, thus enabling AKAPs to coordinate a signaling microdomain containing many of necessary components. In this thesis I present multiple lines of evidence demonstrating how AKAP7g is able to regulate PKA phosphorylation. First, I show that AKAP7g is able to self-associate, forming dimers and possibly higher order oligomers. I predict via computational modeling that this behavior will increase both the speed and magnitude of PKA signaling. Next, I demonstrate that AKAP7g participates in a highly dynamic phosphorylation-state dependent interaction with phospholamban (PLB), and predict via computational modeling that this allows low concentrations of AKAP7g to regulate phosphorylation of much higher concentrations of substrate. Finally I demonstrate via computational modeling that contrary to the widely accepted hypothesis of AKAP signaling, the catalytic subunit of PKA is likely retained within the AKAP-PKA complex during signaling events. I further show that the structure of the complex is an important determinant of substrate phosphorylation. This work offers new insight into the function of AKAPs and offers an update to the AKAP signaling hypothesis.

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