Analysis of post translational modifications in the regulation of cell signaling and behavior

Abstract

Post-translational modifications (PTMs) are chemical or proteinaceous modifications that occur on an expressed protein and can influence protein structure, stability, interaction, and localization. Thus, PTMs represent a mode of proteomic control that is fast, versatile, and dynamic; and regulate a plethora of biological processes, including cell signaling, cellular proliferation and differentiation, cell adhesion and migration, and many more. In this thesis, my aim was to understand the role of PTMs in the regulation of two diverse physiological processes- G protein signaling (primary doctoral project) and extracellular matrix mediated cell adhesion and migration (collaborative project with Professor Thomas Barker, University of Virginia). The first part of the thesis discusses PTM mediated regulation of G-protein signaling, for which I have discovered novel regulatory properties of phosphorylation sites in the N-terminal tails of G gamma subunits. Through a series of biochemical and cellular assays, I showed that phosphorylated G gamma and G beta gamma effector protein, together control feedback mediated regulation of MAPK activation. The second part of the thesis discusses how I have employed mass spectrometry based characterization of citrullination, a rare and understudied PTM that is known to occur on extracellular matrix proteins, such as fibronectin, and disrupt cell adhesion and migration signaling in humans. My hope is that the discoveries made in this thesis will not only further our understanding of PTM mediated regulation of G-protein, but also open avenues for future studies in the field of extracellular matrix biology.